Shrubs and Creepers: 70+ Problems Solved

In this part of our Q & As we answer your questions about shrubs and creepers and other related queries.

All About Bougainvilleas

I have a number of bougainvilleas, planted some 12 to 18 months ago. These plants are flourishing but consist only of greenery and thus, from a color point of view, are most disappointing.

The most likely deficiency which would affect the flowering is phosphate. Give each plant one kilogram of super-phosphate, spread over the root area, and cover with a mulch of compost. Prune the plants and keep them on the dry side (but do not let them flag for want of water) just before the flowering season in early spring.

Our bougainvillea is planted at the eastern side of the house and in five years it has not produced a single flower. We live in a very cold area yet other plants of the same family flower every season.

Try this program. From about spring onwards give the plant 3 ½ oz (100 g) of 2:3:2 one month and the same amount of 3:1:5 the next month until the beginning of autumn. In spring apply 100 g of superphosphate. Keep the ground mulched with compost at all times and about once a month apply Kelpak 66 liquid seaweed as a foliar feed.

Water regularly during dry weather. During winter into spring, keep the plant on the dry side, but do not let it flag for want of water. Then start watering again regularly.

Could you advise me on the correct way of growing bougainvilleas? I have noticed that they do better if north-facing and when they get full sun. Is this true? What type of soil do they prefer and how do you prune them, if at all? Which types are known for their prolific blooming period? 

How does one get a bougainvillea to produce an abundance of flowers? Could you supply me with the names of a good pinkish and apricot flowering plant? What is the best way to propagate these plants? 

Yes, they do like a warm south-facing aspect where they get plenty of sun. They do best in friable soil to which some compost and superphosphate have been added. Place the latter well down in the root area. Prune the long shoots back to five or six eyes from the base. Give the plants a light dressing of general fertilizer, plus some extra phosphate, in autumn and renew the mulch of compost around them.

Water well during the dry winter months, but for about six weeks before they are due to flower, ie, from the end of spring, keep the plants on the dry side but do not let them flag for want of water. This should induce them to flower well.

To propagate, take cuttings of half-ripened wood in August and place them in a mixture of two parts sand and one part peat. Enclose the pot/s in polythene bags. Inflate and tie securely, then place them in a warm, semi-shaded position.

The following. cultivars flower profusely: Barbara Kast, Crimson Jewel, Donyo, Dream, Elizabeth Angus, James Walker, Lady Mary Baring, Master David, Meriol Fitzpatrick, Poulton Special, Temple Fire and Tomato Red. Pink shades: Beryl’s red, pink shading to red;  Donyo fuchsia pink; Natalia, a lovely dusky pink and Rose Catalina. Apricot shades: Blondie, yellowish salmon to dusty pink; Millarii pink/apricot, Mrs McLean, golden yellow shading to pink and apricot.

How does one prune bougainvilleas that have grown wild?

Cut the long shoots back to about the fourth or fifth node from the base and remove twiggy growth. As soon as they start growing again, you must train them, otherwise, you will soon be back to square one.

I have had a white bougainvillea for three years. Last year there were a few blooms, this year nothing. I have fed with 3:1:5 and 2:3:2. The yellow bougainvillea is a mass of flowers.

Give your white bougainvillea 1 lb (500g) of superphosphate, and spread over the root area. Cover this with a generous mulch of compost and water the plant regularly during dry weather, except for the six weeks before it is due to flower when it should be kept on the dry side, but do not let the plant flag for want of water. 

I have a well-established bougainvillea which has plenty of leaves but does not flower. It is in a sunny position against the house. Last winter we cut it right back to induce it to flower. 

Give it 1 lb (500g) superphosphate, spread over the root area, and cover this with a mulch of compost. If possible, keep the plant on the dry side for about six weeks before the flowering season. 

My bougainvillea is planted in a large pot that gets lots of sun. It faces south. The problem is the leaves on the bottom have fallen off and will not grow back, while the leaves grow only near the end. Must I prune it? It also doesn’t flower.

Yes, prune it back quite hard and give it a tablespoon of the fertilizer mixture 2:3:2. In spring, just before it is due to flower, keep it on the dry side for about six weeks, but do not let it flag for want of water. If you prune it back and feed it after flowering, it should flower again for you.

Hibiscus problems

I have a double pink hibiscus. Last year, it was a mass of beautiful large double pink flowers, but many of the buds dropped off before they opened. This year the bush is full of new green leaves but looks rather woody. It has clusters of small buds and single flowers. What can I do to restore this bush to these beautiful large double blooms?

In early summer, give the bush 2 ½ oz (75g) of 2:3:2. Put a  generous mulch of compost over the root area. Water well once a week during dry weather. In winter, prune back quite hard. In spring, repeat the application of 2:3:2 and add the same quantity of magnesium sulfate plus a dressing of iron chelate, (at the rate recommended on the packet) mulch again and water copiously during hot dry weather. With this treatment, the bush should recover.

About five years ago l bought two double hibiscus plants. In the intervening years, I have bought others of different colors. I now have eight bushes. Without exception and irrespective of age, they have all reverted to single blooms. Can anything be done to bring them back to double blooms? They are reasonably protected from the strong winds, but our soil is pure sand. I feed them with 2:3:2 and mulch them with compost. With sandy soil, shouldn’t compost be dug into the sand as well as using it as a mulch?

 In spring, prune the bushes fairly hard. Instead of giving them 2:3:2 in at the beginning of the season, substitute superphosphate, giving each bush about 3 ½ oz (100g). About mid-season you can give them a dressing of 2:3:2. Go on mulching the ground frequently; as soon as one lot of mulch has broken down apply another. If you dig around the plants you will disturb the feeder roots that the bushes have sent out into the mulch. Water copiously during dry weather. 

I have a hibiscus hedge. The leaves on one branch will suddenly start to wilt until the entire bush is just a mass of shriveled sticks. The leaves also turn yellow and blotchy. What fertilizer should be used on the hedge?

There may be several reasons for the trouble. The plants may be attacked by borers. Inspect the plants carefully and if you find signs of the borer, cut the infected branch off and spray thoroughly with Karbaspray or Karbakil, (active ingredient carbaryl) or systemic insecticide such as Metasystox (active ingredient oxydemeton-methyl). The plants may not be getting sufficient water. Hibiscus are tropical plants and need abundant water during dry weather.

The plants may be lacking essential elements: yellow leaves, especially older ones, indicate a lack of nitrogen. Leaves turning yellow from the edges is usually a sign of potassium deficiency. Give the hedge a dressing of 2:3:2 at the rate of 4 oz (115 g) per 3 ft (1 m) of hedge (the same quantity on both sides). Spread this out starting a few centimeters away from the stems and going out about 15 in (400 mm). Water in thoroughly after application. 

I bought six hibiscus shrubs with double blooms two years ago. They flowered only once, then the buds started to fall off. First, the leaves started to turn yellow and eventually dropped off. The buds form but never open. I fed with Superphosphate, magnesium sulfate, and 3:1:5 at different intervals.

I think the trouble with your hibiscus could be caused by a lack of sufficient water. Hibiscus are tropical plants and need abundant water. Mulch the ground under them with compost and water very well at least once a week.

I have a hibiscus that always has plenty of buds but the buds dry up and drop off before they open. I have been watering the shrub well. Many of the buds have a tiny hole in the side and I often find very small black droppings on the leaves near the buds, I have been told about a hibiscus weevil which feeds on the flower buds and young growing tips.

Try spraying the bush with Karbaspray or Karbakil (active ingredient carbaryl) once a week and/or splashing bait with Dipterex (active ingredient trichlorfon) on the  growing tips where the buds are, doing this once a week. You will find directions for making the bait on the Dipterex container. Keep the ground  under the bush mulched with compost.

I planted a hibiscus hedge, which I grew from slips, about three years ago, in the front of my garden. The hedge appears to be dying: it seems to have a disease that causes the leaves to die off and the plants become very bare. This disease started on one plant and has now spread to others. I have sprayed with various insect sprays but nothing seems to help. 

The only disease your plants could be suffering from is wilt. This is usually caused by poorly drained soil which remains water-logged during prolonged rainy weather. With the present drought conditions, this could hardly apply. If your soil is poorly drained, then make inverted saucers, ie, make mounds around the stems of the plants so that water never gets nearer than about 18 in (45 cm) from the stems, and do not overwater.

The only other cause of the trouble could be insufficient water. Hibiscus are tropical plants and need regular watering. If your soil drains well and does not get waterlogged, put down a generous mulch of compost and water regularly and thoroughly. 

My hibiscus grows very well, but they flower very sparingly. If I prune them, will they improve? When and how does one prune?

Prune your hibiscus in winter, cutting the side branches back by a third to a half, and removing any very thin twiggy growth. Do not cut into the thick wood. Give them a dressing of superphosphate and cover it with compost. Water well at least once a week; they need quite a lot of water.

Growing Rhododendrons (aka Azaleas)

I have three rhododendrons growing on the north side of the house. There is a wall on the east side of the bed, so these shrubs get little or no sun except for a short period in the afternoon.

The one in the corner and the one next to it are very healthy and flower well, but the third one, farther to the west, which gets morning sun and is not sheltered as much from the west wind, is miserable.

The leaves have brown spots and the main stem and some of the branches are covered with powdery stuff that is perhaps a moss. I have sprayed all three shrubs with Benlate and Funginex. The leaves of the diseased shrub fall off; new leaves start off looking healthy, but soon they also develop brown spots.

All three were planted in an acid soil mixture of loam, peat moss, and pine needles and are mulched with pine-needle compost. feed them once a month with 2:3:2, Epsom salt, and Kelpak 66, alternately.

 Perhaps the rhododendron which is farthest to the west does not get as much water as the others. Foliar feed with Kelpak 66 about once a week. Spray with any remedy that has copper oxychloride as the active ingredient, eg. Cupravit, Virikop, Blitox, etc, for the powdery moss/fungus on the stems. 

Can you give me some information about caring for azaleas? Should they lose their leaves in winter? I give all my shrubs an application of 2:3:2 fertilizer on a regular basis during the growing period.

All azaleas, except A. molis, are evergreen and they should not lose their leaves in winter. Azaleas do best in semi-shade and must have acid soil. They must also be watered regularly throughout the year when the weather is dry. Hose the foliage down when it is very hot and dry. In spring, feed with special hydrangea fertilizer.

It is correct to give your shrubs 2:3:2 during the growing season but about two applications, one in spring and the other in midsummer, should be sufficient. Keep them mulched with compost.

I should like to start propagating azaleas from slips.

Azaleas put out new growth in early summer after they have finished flowering. In July,  when this new wood has firmed, you can take cuttings. The cuttings need not be very long, 2 to 2 ½ in (5 to 6 cm) would be quite long enough. Cut just below a node or leaf joint and trim off the lower leaves. Dip the ends into a rooting hormone, then place the cuttings either in sand or a mixture of two parts sand and one part peat. Water well.

When the pots have drained, enclose them in polythene bags. Inflate these by blowing into them and tie securely.  Place the pots in a semi-shaded place and leave them for a month to six weeks, when the cuttings should have rooted. Take off the plastic bags and harden the cuttings off. When growing well, pot them up into an acid soil mixture.

I have two azaleas in large buckets filled with peat moss; the plants are given occasional mulch with tea leaves and hydrangea food. However, many of the leaves are showing signs of yellowing and one, in particular, is really bad.

Your azaleas are probably suffering from iron deficiency. Give each bush a  dressing of iron chelate at the rate recommended on the container and a tablespoon of magnesium sulfate (Epsom salt). Water before and after application It will take from six to eight weeks for the effects of this treatment to be apparent.

Can azaleas be transplanted? The present position exposes the plants to the hot afternoon sun.

Azaleas can be moved. Do this just after the flowering season, but before they start putting out their new growth. Prepare the new holes first, digging in acid compost and/or peat, then lift the bushes with as large a ball of soil around their roots as you can manage. Plant immediately and water in.

How does one prepare the soil for azaleas?  

As you probably know azaleas must have acid soil. Dig in plenty of acid compost and a dressing of superphosphate at the rate of 1 lb (500g) per square meter. Pine needles, oak, wattle and tea leaves make good acid compost. If your soil is alkaline, sprinkle sulfur in the holes as you plant the azaleas, and sprinkle some over the soil from time to time to keep the soil acid. 

I should like to grow coprosma (marble chips) as a hedge. So far I have been unsuccessful in growing them from slips. Do they need special growing conditions? A  warm, moist, misty atmosphere? How does one achieve these conditions and would growing them in potting soil obtained from the nursery help? What is the best time to start?

Take half-ripe cuttings, that is, cuttings of new wood sent out in spring doing this from March to April. Prepare the cuttings in the usual way by removing the bottom leaves, then dip the ends into the rooting hormone Seradix No 2 for half-ripe cuttings, and insert them into clean sand or a mixture of two parts sand and one part imported peat. Firm them in and water. Place the pans of cuttings in polythene bags, inflate by blowing into them and tie securely at the top. Keep the pans in a warm semi-shaded place. They should not need watering again until they have rooted.

When they have rooted, harden them off and water them once a week with Kelpak 66 liquid seaweed to encourage good root growth. When the cuttings are large enough, you can plant them out in the garden in good soil enriched with compost and a dressing of superphosphate at the rate of ½ pound (250 g) per square meter.

What position is recommended for a Dipladenia? East-facing with full morning sun, west-facing with the semi-morning sun but full afternoon sun, or a shaded area? Does it need fertilizer? Is pruning necessary?

 The plant has been re-named and is now known as Mandevilla splendens. A semi-tropical coastal region is ideal for this creeper: it likes humidity. An east-facing position would be ideal. If you plant it next to a wall, you must allow at least 24 ins (60cm) between the wall and the trellis on which the creeper is to be trained to allow a free circulation of air. It does not need any pruning but you can remove the old flower stems after flowering.

Water freely during dry weather in summer, but less frequently in winter. The plant develops thick fleshy roots, so do not cultivate around it, but keep the ground well mulched with compost. During summer, feed every two weeks with a liquid fertilizer such as Seagro, Nitrosol, Multi-feed P, or Lush. 

Propagating Tibouchina

My Tibouchina and hydrangeas face east and do not get the very hot afternoon sun. The edges of the leaves turn brown and the plants look very miserable. I have been told it is sunburn.

As a rule, when leaves turn brown around the edges it is a sign of potassium deficiency. Dissolve a tablespoon of the fertilizer mixture 3:1:5 in 1 gal (4,5 L) water and apply this quantity to each plant. Apply to damp soil and water lightly afterward. You can give this amount about once a month until the plants improve.

You can also give them the same quantity of magnesium sulfate – just scattering this on the ground and watering it in. One application in spring and another in autumn should be sufficient. Keep the ground mulched with compost and water regularly.

How does one propagate tibouchinas? I understand it is not done in the common way of taking cuttings. Are they acid lovers? We live in a rather windy area, not too close to the sea, and the soil is very sandy.

You should not have any trouble striking cuttings of tibouchinas. Take cuttings of half-ripe wood in early summer, prepare in the usual way, and put them in pots filled with sandy loam. Dip the ends of the cuttings in a rooting hormone, insert them in the pots, firm in, and water. After they have drained, place a few stakes around each pot, then put the pots in polythene bags.

Inflate the bags by blowing into them and securing them firmly at the top. Keep the pots in a warm, semi-shaded place, and the cuttings should root in a few weeks. The inflated polythene bags provide the “close moist atmosphere” the plants need for rooting. As soon as they have obviously taken, gradually harden the plants off and, when they are growing well, transplant them into pots.

When they have settled down in the pots and started to grow, pinch them back to encourage bushy growth. They will grow in soil with a pH of 6,5 with plenty of humus in it.

About six months ago we planted a tibouchina. We were told it is too windy for it here. We put peat, sand, and compost into the hole – we have clay soil – and now we have removed the tree as the leaves all fell off and it did not grow at all. Upon taking it out, we found a mass of hair roots which, for a shrub, seems a bit odd. We have put it into a pot as it is not absolutely dead.

 If your soil is clay and presumably does not drain very well, filling a hole with sand, peat and compost will not improve the drainage. The plant may have been suffering from overwatering. Putting it in a pot should have improved the drainage but, if the pot is placed in the ground, especially clay soil, it will not drain freely. Why not try growing it in a large pot in the garden in a position that is sheltered? When growing tibouchinas in windy places, they should be pruned back hard to reduce wind resistance.

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Hydrangeas becoming stunted & more

Our house has very deep eaves and on the north side, we have flowerbeds built beneath.  For many years I have had hydrangeas growing in these beds. At the back of the beds, growing all over the north side of the house is Virginia creeper.

For the past couple of seasons, however, the hydrangeas seem to be becoming stunted. I have even planted new ones to fill in and raised the beds by two bricks to enable us to add more compost and peat.

The creepers are causing the trouble. I suggest you redo the bed, bit by bit, removing a hydrangea or two at a time and heeling them in somewhere. Then remove the peat and compost you have added, plus about 4 to 5 in (10 to 12 cm) of soil below that. It will probably be full of roots, but do not think it will harm the creeper to have some of its surface roots removed. Then fill in with good soil mixed with superphosphate, mixed with the peat and compost you took out. Then replant the bushes you have heeled in. You do not say whether you ever feed your hydrangeas. In spring. give them a dressing of 2:3:2 and a mulch of compost.

I invested in some hydrangea plants for an east-facing bed with sun until 10 am, thereafter full shade. I dug the bed well, and used plenty of compost and corral manure and a dressing of 3:2:3. The plants get a fair amount of water, but are very slow and have developed what looks like powdery mildew.

Hydrangeas are shallow rooting plants and need abundant water. keep the ground around them mulched to conserve moisture. During summer, feed them once a fortnight with Nitrosol, applying this to the soil when it is moist. Spray with Benlate (active ingredient benomyl) for mildew.

If you spray and water more frequently, (if possible) the mildew will disappear. Prune the bushes in winter, taking out the oldest wood and any very thin spindly growth. Do not cut new growth which has a bud on top, but trim the other strong stems back to a pair of plump buds, shaping the bushes at the same time.

You mention that to improve the color of pink hydrangeas a light dressing of lime and a tablespoon of Epsom salt per bush should be applied. What is the best time for this application and how often should it be done? For how long? To what part of the bush or soil should it be applied?

 Apply the lime in autumn, just before the rainy season, scattering it in a circle, 2 ft (60 cm) in diameter, around each plant. Apply the magnesium sulfate in spring and repeat the application in fall when the plants are in bud, scattering it over the same area.

There is a  special hydrangea fertilizer on the market for pink hydrangeas, also one for blue hydrangeas, which you might like to try. 

Hydrangeas growing under a deodar in my garden bloomed magnificently for three years. For the past two years, the foliage growth has been luxurious, but they have not borne any flowers. Could you please help me with this problem?

Your hydrangeas are getting too much nitrogenous fertilizer. In spring, give each bush 250g of Superphosphate and a mulch of acid compost. Pine needles, oak, wattle, and tea-leaves make good acid compost. This treatment should induce them to flower again.

I have four blue hydrangeas which are in a hidden area behind my garage and this summer I discovered them in bloom, looking splendid. I should like to transfer them. Is this possible? What position and type of soil preparation are required before transplanting? At what time of the year must this be done? Should I prune them before or after transplanting? How much must be pruned off? The bushes are quite old, as the trunks are thick.

If you are prepared to go to a great deal of trouble you can try to transplant your hydrangeas, but to move such large plants you will have to dig them out with large balls of soil around their roots, and even then the operation might not be successful. It would be far better in the long run to take cuttings and, when these have taken, plant them where they will be seen. Hydrangeas do best in a  semi-shaded position.

If you decide to move the plants, dig large square holes and fill these with soil mixed with a generous quantity of acid compost and/or peat, preferably imported, and ¼ lb (100g) superphosphate per hole. This must be put well down in the root area. Move the plants at the beginning of spring and cut them back by about two-thirds.

I have been growing hydrangeas for a number of years, with the plants bearing quite a number of flowers. The problem is that the flowers are never the right color. The pinks are a very pale pink, almost off-white, and the blues are extremely pale as well.

To improve the pinks apply a light dressing of lime and a tablespoon of magnesium sulfate per bush. If the pink bushes are next to the blue bushes, you must be careful as the lime will affect the color of the blue flowers They need acid soil.

To improve the color of the blue flowers, give the plants an application of iron chelate (at the rate recommended on the containers) and about two tablespoons of magnesium sulfate for a large bush.

Keep the bushes mulched with acid compost and/or peat and sprinkle sulfur over the ground from time to time to keep the soil acid. You can also give them an application of ammonium sulfate (a level tablespoon dissolved in 1 gal (4,5 l) water) about every three months. Pine needles, oak, wattle, and tea leaves make good acid compost. You should be able to get all the fertilizers mentioned at garden shops and hypermarket garden shops.

For the last two seasons, my hydrangeas have been very poor. The leaves have turned yellow and there have been very few blooms. They are north-west-facing, planted against the wall of the house. After pruning, I gave them a handful of 2:3:2, some poultry manure and compost, and 2 oz (60g) of Epsom salt. When the leaves turned yellow, I sprayed them with iron chelate and gave them a tablespoon of sulfur, but it didn’t help. They have also been attacked by something: the leaves are curled up. They are very old plants.

 As they are old plants, I suggest you prune them fairly drastically next winter, taking out quite a bit of the oldest wood. In spring, give them a generous mulch of compost,  two tablespoons of sulfur, spread out over the root area, an application of iron chelate watered on top of that, plus 60g of magnesium sulfate.

Two or three weeks later, apply 100g of the fertilizer mixture 3:1:5. Water before and after applying the fertilizer. I would alternate feeding with hydrangea fertilizer with a liquid seaweed feed, and feed twice a month. Keep the plants well watered at all times and renew the mulch from time to time. If you can get compost made with pine needles, that would be excellent.

Without seeing the leaves, it is difficult to say why they are curling, but it is possible that the plants have mildew. Spray them once a week with Benlate or a copper spray eg. Blitox.

What is the cause of hydrangea flowers remaining green?

The color of hydrangeas is influenced by the pH of the soil, although it is claimed that the colors of the modern hydrangeas have been “fixed”.  The blooms tend to go green towards the end of the season, probably because of the lack of some trace elements in the soil.  Further research is being done on the subject.

I have two ixora shrubs, both very young, and about six months old. Can you please give me advice on their culture? We have a very open windy garden.

Ixoras will grow in any good friable soil. They must be kept well watered, especially during summer. Prune the plants after they have flowered, cutting the flowering stems back by about a third.

What is the feeding program for camellias?

In spring give each bush 2 oz (60 g) magnesium sulfate and about two tablespoons of 2:3:2. Mid-spring give them 1 oz (30 g)  ammonium sulfate dissolved in water and applied as a liquid. Mid-summer 2 oz (60 g) superphosphate and one oz (30 g) magnesium sulfate are applied. The ground under the bushes is kept mulched. From the end of summer, the bushes are watered thoroughly once a week and, as some winters are dry, this is kept up until the summer rains start. This watering is important: if the plants lack water when in bud and flowering, the buds do not open properly and eventually drop off.

Could you give me information on how to plant proteas and how to care for them? We get heavy frost in winter. I fed my one protea with 2:3:2 and mulched with compost and watered at least once a week during dry weather.

The majority of proteas come from the winter rainfall areas where they do not have heavy frosts, so, if you plant any, you must put them in a sheltered position in the garden. They like a free circulation of air at all times: do not put them in a stuffy corner. The plants prefer acid soil.

When preparing holes for them, add acid compost made of pine needles, wattle, and tea leaves. Buy small specimens, plant them firmly, and then do not cultivate around them. To  prevent any cultivation around them, put some flat stones on the ground.

Keep the plants mulched with compost at all times. In winter, water well at least once a week. Instead of feeding with 2:3.2, use old well-rotted manure mixed with compost. 

Some months ago I planted several frangipanis in two pots. They have taken very well and have been flowering for quite a while. When must I transplant these into the garden? What type of soil and position? At the moment they get morning sun only and a lot of southeaster (wind), which does not seem to affect them. Must l add fertilizer to the soil when planting out?

You can transplant your frangipani into the garden in early autumn, so long as the ground into which they are to be planted is well drained. Dig square holes and mix about 5 oz (150 g) of superphosphate with the bottom soil in the holes. Do not put in any other fertilizer.

After you have transplanted the cuttings and watered them in, put down a mulch of compost, but do not pile this up against the stems.

I want to plant a jade vine. What type of soil and position? Should it be in full sun or shade? believe it does not like an open position where gets too much wind.

The jade vine must have good soil, rich in humus. I have seen it growing very successfully on a south-facing pergola in dry areas, but Some authorities say it needs semi-shade. Shade the roots with a deep mulch of compost or slate while the plants are small; when it grows it will provide its own shade.

It must have high humidity, so water well during dry weather in summer. It probably would not tolerate strong winds.

I have a hoya carnosa in a very large pot. It is six years old, and the leaves are very healthy, but it has never flowered.

 Hoyas do not like being overpotted, that is, planted in large pots. As it would be difficult for you to move the plant, all I can suggest is that you give it about a tablespoonful. of superphosphate in spring. Water sparingly in winter, but do not let the soil in the pot dry out.

I obtained a cutting of a hoya about two years ago and planted it in a pot. Since then it has just continued to exist, without putting out any shoots.

 The plants are very slow growing. Someone gave me a cutting many years ago and it has only reached a height of about a meter and a half (4 feet) and has flowered for the first time this season. During summer, feed the plant with Seagro fish emulsion or Kelpak 66 liquid seaweed or Nitrosol at half the recommended rate every three to four weeks.

Water once a week in summer and once a fortnight in winter. I do hope you have put it in a fairly small pot. The plants dislike being overpotted, ie, put into a large pot.

Could you give me some kind of blueprint for looking after shrubs and trees? When we plant them, we manure and compost well, but it is the after-care with which we need advice.

Should one compost and manure once a year? Can one give too much compost and manure? Should one, in addition to this, use a fertilizer? I know a number of fertilizers refer to the proportion of nitrogen, phosphorus, and potassium. Which promotes rapid growth and which promotes blooming?

All About Applying Fertilizer

How often, how much and when should one apply fertilizer? Is there a difference in approach to the fertilizer of ornamental flowering shrubs as opposed to shrubs that are grown predominantly for their foliage? 

When you plant trees and shrubs you should dig square holes, at least 12”x 12” x 12” (30 x 30 x 30 cm) for small plants and up to 18” (45 cm) for large ones. Make the holes on the large side rather than on the small side; the larger the hole the better the shrub/tree will grow. You can add some well-matured compost and superphosphate 9 oz (250 g) for small plants and 2 lb (1 kg) for large ones). Mix these well with the soil. Do not put any general fertilizer or manure in the holes: these could burn the roots.

When the shrubs/trees have been planted, make a shallow basin around each plant and water really well. Put down a mulch of compost. For the first 12 to 18 months water thoroughly and regularly when the weather is dry. Always keep the ground mulched: this makes a great deal of difference to the way in which the plants will grow and thrive. Never pile manure or compost up around the stem/trunks of the plants.

In spring, give them a dressing of manure and/or fertilizer (2:3:2). Always apply fertilizer to damp ground and water in well afterward. Acid-loving shrubs, such as azaleas, camellias, etc can be given an application of magnesium sulfate (Epsom salt) from time to time, the amount depending on the size of the plant, starting with 1 oz (30 g) for a small plant and going up to 2 oz (60 g) for large plants.

Fertilizers: Nitrogen promotes vegetative growth, large dark-green leaves, and bulk and is important for leaf crops, such as cabbages. It also increases the plumpness of seeds and the size of flowers. If there is insufficient nitrogen, the older leaves gradually turn yellow and growth is slow and stunted. Too much nitrogen results in soft, sappy growth, weak stems, and rank growth that is susceptible to damage by cold and certain fungus diseases (mildew). 

Phosphorus promotes and hastens the formation of flowers and fruits and is of great importance for crops grown for their seeds and fruits. It also helps to increase the efficiency of the plant’s mechanism for making chlorophyll (green coloring matter in leaves)  as well as helping plants to take up potassium and counteract the effects of much nitrogen. It is valuable for root crops, as it plays an important part in changing starches into sugars. Plants seldom show signs of an excess of phosphorus. As phosphorus moves through the soil slowly, it should always be put well down in the root area.

Potassium affects the general vigor too of plants and is concerned with the manufacture of sugars and starches. The effects of nitrogen and potassium counteract each other and a proper relationship must be maintained. Deficiency shows up as yellowish mottling of the leaves, starting at the edges and tips of the leaves, gradually progressing towards the center. The lower leaves are affected first and they may eventually turn light brown and fall off.

Another symptom is poor quality fruits and potatoes. Too much potassium results in hard, very stocky growth. Calcium, magnesium sulfate, and trace elements also play a part in plant nutrition; if sufficient nitrogen, phosphate, and potassium have been supplied and plants still do not thrive, then they may be lacking in one of these. It is best to use a balanced fertilizer. unless you have had your soil analyzed and it is deficient in one particular element.

Fertilizers are always mixed in the same order: nitrogen – phosphorus – potassium (NPK) and from the figures on the bags you can choose the mixture that suits your needs best eg. 2:3:2 is a good general mixture for most plants, 3.1:5 is useful for root crops, tomatoes and other plants that need more potassium.

For several years we have had a number of flowering ginger plants that do not flower. We had them growing in a  shady, but a fairly damp spot in our garden, and although they were thriving, with lots of lush foliage, they just would not flower.

Someone suggested we move them and said ginger does not like wet conditions. This we did, transplanting them into a much drier locality, under a large tree in the garden.

Growing with them in the same bed we have a number of azaleas and a large philodendron, which are all thriving, but the ginger, after being there for well over a year, still will not flower.

The plants like rich, moist soil. Keep them well watered during summer and autumn, but keep them on the dry side during winter. Partial shade suits them best, and I think you may have moved them to a site that could be a little too shady. You can move them in spring. 

I have lilac planted under a pine tree next to azaleas. Can you give me some information about their likes and dislikes?

Lilacs like rich, moist alkaline soil and can be grown on the north side of the house or on a wall. Move them to a more suitable position and prepare square holes for them, adding compost and superphosphate at the rate of 1 lb (500 g) per hole and, if your soil is alkaline, a dusting of agricultural lime.

Keep the plants watered during the dry winter months; in spring give them a light dressing of 2:3:2 about 2 oz (60 g) per plant. If the plants send out suckers, remove them promptly. You can increase your stock by planting these. As the plants grow, you can prune lightly to shape immediately after flowering, that is, in early summer.

WHEN AND how should go about pruning a wisteria? What must feed the plant with and when?

You can prune your wisteria immediately after flowering. Cut the long side shoots back to the fifth bud from the base. In spring give the plant a dressing of superphosphate, about 1 lb (500 g) spread out over the root area, and cover that with a generous mulch of compost. This, too, should encourage flowering.

My wisteria looks healthy and grows in the ground on the south side and climbs on the pergola of the veranda. It has been in the ground for six years and has never flowered. I have given it 2:3:2 and compost. Our soil is acidic.

In winter, prune the wisteria, cutting the long shoots back to about five buds from the base. Give it about 18 oz (500 g) of superphosphate, and cover this with a  generous mulch of compost and water well. If the plant still does not flower, root prune it the following winter.

Open up a trench about 3 feet (1 meter) away from the main stem, going only halfway around the plant, and sever the roots in this trench, then fill in the soil again, mixing some superphosphate with it. 

Pride of India is a healthy-looking shrub and flowers every year. However, every year the leaves and flowers are covered with a white powder for which I have not treated.

 Pride of India has mildew. In winter spray the bush twice with winter-strength lime sulfur (one cup of lime sulfur to eight cups of water) allowing 10 days between the applications. When the leaves come out in spring, spray every two weeks with Funginex (active ingredient triforine), and when the flower buds appear water the plant regularly.

I bought a Chinese bamboo and planted it in full sun. Does it like a lot of water and fertilizer? How high does it grow? It is planted against a wall.

Bamboos need good soil with plenty of humus in it and a lot of water during the growing season. There is no need to feed the plants, but you can give them a little Seagro fish emulsion from time to time in summer. As most bamboos spread, the plant might have an adverse effect on the wall in time.

I have a Chinese lantern planted from a shoot and it is growing very well. When does it flower and how much water and fertilizer does it need?

The Chinese lantern is an abutilon, which flowers in summer. In spring you can give it an application of 2:3:2, say about 2½ oz (60 g). Water regularly during dry weather. You do not need to water frequently. 

I planted proteas and heather against a ridge and I installed a sprinkler system. The plants get afternoon sun and I water them regularly. After a good growth, the stems and branches on the proteas and ericas split lengthwise and the plants die.  

I can only put the splittin of the bark down to extremely hot and dry weather in summer. Even when it is hot, there is always a certain amount of humidity at the coast, but inland the humidity can get very low. Try to mist your plants down as often as you can during the dry, hot weather. Water regularly in winter.

My strelitzia reginae, two plants, get buds, but more often than not they do not open. I have cut off all the failures but perhaps I should have examined them for worms or suchlike by cutting them open. There is a sticky substance where the flowers should bloom. Both plants get sun, but not all day, and they are both on level ground. We mulch our soil, which is rather sandy.

If the flower-heads are sticky, some insect may be attacking them. Spray with Malathion about once a week for several weeks and see if the  plants improve. If there are any ants around the plants, get rid of these as they encourage insects that secrete honeydew, a sticky substance. Keep the ground well mulched and water regularly.

WHAT IS  the correct way of removing strelitzia blooms when they have finished flowering? Do I cut off the stem top, middle, or bottom, and will it develop more flowers, or do I pull the stem out?

If your strelitzia stems come away easily, pull them out, but if they offer any resistance it would be better to cut them down as far as you can reach among the leaves. They do not send out flowers from the old flowering stems but from the base of the plants.

I have an enormous strelitzia. It gives dozens of leaves but only one or two flowers a year. It is about 20 years old. How can I propagate this plant and increase the amount of flowers? 

You can either lift the whole strelitzia plant and divide it or you can cut pieces off with a sharp spade. Whichever you do, it will take quite a bit of digging and cutting: the plants get tough when they are old.

If you decide to divide the whole clump, do not divide it into very small portions. Replant in well-prepared soil. Dig large hole/s and put plenty of compost in it/them, with a dressing of superphosphate, about 1 lb (500 g) per hole.

If you decide to take just a portion from the side of the clump give it a dressing of compost and 2:3:2, about 7 oz (200 g), spread around the clumps, then water thoroughly once a week when the weather is dry even right through winter 

I planted ginger lilies three years ago and I am still waiting for them to bloom. What are their requirements?

Ginger lilies need good friable, well-drained soil and plenty of water during the growing season (summer) and less in winter. In spring, cut the foliage down to ground level, give the plants a dressing of superphosphate 1 lb (500 g) a clump, and mulch with compost. They flower best in a position where they are in shade during the hottest part of the day.

I HAVE not been able to grow a jade vine successfully. I have bought plants at various times. I should like to plant the jade vines on an enclosed patio. I believe if the stem is protected in winter the vine should grow there. The patio gets a lot of south sun and has a fiberglass roof.

The jade vine comes from the Philippine Islands and needs warmth and humidity all year round. Unless you have a heated greenhouse, you would not be able to grow the plant. 

When is the best time to move a large camellia?

The best time to transplant a camellia is at the end of winter just before the plant puts out its new growth. Prepare a large hole for the shrub in the new site, then dig the plant up with as large a ball of soil around its roots as you can manage. Replant immediately, putting it in at the same depth it was growing before. Trim the top growth back to about a half to compensate for the loss of root growth. Keep the bush damp, but not saturated, and mulch the soil to conserve moisture. 

I have had a lobster claw for about 12 years. It has never flowered. I tried it against the house on the east side in an open herbaceous border where it is protected against the north winds. It was watered regularly with all the plants and mulched thrice a year with compost made of leaves, lawn cuttings, and farmyard manure​​.

Lobster claw, heliconia, is a tropical plant and needs rich, loamy, well-drained soil, warmth, and abundant water during the growing season, but less water in winter. Try giving your plants a dressing of superphosphate, about two heaped tablespoons per plant, mulching with compost, and watering frequently in summer. You can also give them an application or two of Kelpak 66 liquid seaweed when they start into new growth in spring.

Can one prune lavender bushes and how drastically can this be done?

You can prune the lavender bushes back, but you must not cut into the hardwood, in other words, prune lightly. Take cuttings and raise some young plants, then you can replace the old ones.

My hydrangea’s leaves are healthy and green, but it does not flower. The other bush is also very healthy and covered with blooms. Both get the same treatment and are in the same position.

There is probably not sufficient phosphate in the soil. Scatter 2 ½ oz (75g) of superphosphate around the bush and cover this with a  generous layer of compost and keep the bush well watered.

Can you tell me of an evergreen creeper, preferably fast-growing, that  I could plant against a smooth south-facing wall? This is an outside retaining wall and looks very bare. In the autumn planted a Bignonia Cherere against this wall and it grew well until the hot weather when it definitely deteriorated, and some of the leaves went black.

You could plant an Allamanda cathartica against your outside wall it will tolerate sun and wind. Bignonia capreolata, the Cross vine, will also grow in sun and tolerates wind. Other creepers that would be suitable are Gelsemium Sempervirens and bougainvillea, which will tolerate some wind. Before planting a new creeper, prepare a large square hole and put 8 oz (250 g) of superphosphate at the bottom of the hole, well mixed with the soil. After planting, mulch the ground with compost and water regularly. You can plant your Bignonia Cherere, (the correct name is now Phaedranthus buccinatorius)  where it gets sun but is sheltered from strong winds. It does best in rich, moist, well-drained soil with plenty of humus in it. 

I RECENTLY moved into an old house that has a neglected garden. What do I do about a gardenia bush? It is quite a large one, the buds appear, turn yellow, and drop off. Can I divide the bush?

Give the bush a generous mulch, at least 2 in (5cm) thick, of compost and/or peat and the following fertilizers: 1 lb (500 g) of 2:3:2, spread over the root area, some iron chelate at the rate recommended on the packet, and ½ lb (250g) of magnesium sulfate. Water the bush thoroughly once a week.

No, you cannot divide the bush: it will probably die if you interfere with it in any way.

Some years ago we planted three wisterias. They have grown well and cover a pergola. All the plants bear strong, green leaves and appear quite healthy. Last year one bore a few pale mauve flowers. This year the same plant has many flowers, also pale. The other two have never flowered. Is there anything we can do to deepen the color of the flowering one and induce the others to flower? They are growing in a warm, dry, well-drained spot.

There is very little you can do to improve the color of the wistaria which has flowered. There are two color forms of the mauve wisteria, one pale mauve, almost grey, and the other a deep lavender, and it is best to select plants while in flower to ensure you get the deeper, more attractive form. The color may improve a little if you give the plant 250g of magnesium sulfate at the beginning of winter.

To get the other two plants to bloom, prune the long shoots back to five buds from the main stem, doing this in winter. Give each plant 1 lb (500 g) of superphosphate, spread over the root area but not against the stems. Put down a generous mulch of compost and water well during the spring months, if the weather is dry. 

What type of soil does a jade vine require? Does it prefer full sun or a shady position? Our prevailing winds are south-westerly and the soil is rather acid.

It is a tropical creeper from the Philippines and needs warmth – the ideal temperatures being 27-30 degrees C day, and 16-18 degrees C night, although they can tolerate lower temperatures without harm. It also needs humidity and good garden soil with plenty of humus in it. Keep the plant evenly moist but not constantly wet. Spray with a fine spray during very hot, dry weather, such as you probably experience when you have mountain winds.

I suggest you grow it on the southeast side of the house where it will be in full sun and protected from the prevailing winds. It is a vigorous-growing creeper and needs a sturdy trellis. The flowers show off best if the plant is trained over a pergola and the long trusses can hang down.

For some time my gardenia has had black “scale” on top of the leaf, with small creamy-colored spots on the underside. It has been sprayed with several different garden sprays but to no avail. The leaves eventually fall off.

The little creamy spots on the back of the leaf are scale and for this, you must spray with Malathion (active ingredient mercaptothion) plus an oil spray such as Oleum, Evoleum, etc. at quarter strength. Pay attention to the undersides of the leaves. If there are any ants near the tree you must get rid of the ants, as they encourage the scale.

Once you have got rid of the scale and the ants, the sooty mold on the surface of the leaves should clear up when hosed down with water. The mold is caused by the honeydew secreted by the scale going moldy.

WHAT ARE the soil requirements for Azalea mollis? Can these plants be transplanted during any season in the lowlands?

Give the azalea good, friable, acid soil with plenty of humus in it. Compost to which super-phosphate and seaweed meal have been added would be good. Feed with Seagro fish emulsion or Kelpak 66 liquid seaweed and water freely. It would be best to transplant in spring. They flower best when grown where they get morning sun.

Does petrea need any special treatment? I give it iron chelate periodically.

Keep your petrea mulched with compost. Do not dig around it. Give it 1 oz (30 g) of magnesium sulfate once or twice a year and, if it is not thriving, a foliar feed of Kelpak 66 liquid seaweed every two weeks during summer.

Our garden soil is alluvial and, in the main, exceptionally fertile. There are, however, areas where we are having problems that no amount of the correct application of fertilizers, compost, water, and loving care has overcome. A brunfelsia’s leaves turn yellow and fall off within weeks of developing, and there is a bed, adjacent to a cement wall, in which we have found it almost impossible to grow plants of the quality of those in the rest of the garden. 

It sounds as though the brunfelsia is suffering from nitrogen deficiency. Apply ammonium sulfate at the rate of a tablespoon for 10 sq. ft (1 sq m). Dissolve this in water and apply it as a liquid. Apply magnesium sulfate at the same rate and in the same manner. You can repeat the application of ammonium sulfate in four weeks time.

Try digging some acid compost (pine needles, oak, wattle, and tea leaves make good acid compost) and/or imported peat into the soil next to the cement wall and applying ammonium sulfate and magnesium sulfate as recommended for the brunfelsia.

The soil may be lacking trace elements as well, and I suggest you dig in some Kelpak seaweed meal. This will not only provide trace elements but also improve the tilth of the soil.

In midsummer, I planted a Camellia japonica. It produced a few new leaves, but now the leaves are turning brown along the edges. It faces east.

Give the bush two heaped tablespoons of the fertilizer mixture 3:1:5 and the same amount of magnesium sulfate, scattered over the root area but not against the stem; cover with a thick layer of compost and water the bush well once a week until the regular rains start.

From summer onwards water once a week during dry weather and continue right through winter.

Could you please describe the methods of propagating dipladenia and jade vine? Are the climbing shoots layered or struck? Would the medium be compost or soil and sand in plastic bags? What is the best time of the year to propagate? 

Both dipladenia, now known as Mandevilla splendens, and the jade vine can be propagated from cuttings of young growth taken in spring. Prepare the cuttings in the usual way, ie, cutting just below a node and removing the bottom leaves. Dip the ends into a  rooting hormone and insert either into pure sand or a mixture of two parts sand and one part peat, then firm in well and water.

Enclose the pots of cuttings in polythene bags. Inflate the bags by blowing into them and tie the tops securely. Place the pots in a warm, semi-shaded position; the cuttings would also root well under mist propagation.

It is quite easy to erect a small mist propagation unit. Choose a site in full sun and enclose an area about 4 sq ft (1,2 sq m) with wire mesh 3 ft (92 cm) high and cover the mesh with heavy-gauge transparent polythene (this is to protect the cuttings from the wind and prevent the spray from blowing about). Suspend one microjet nozzle over this about 1 ft (30 cm) above the cuttings. Place a generous layer of chipped stone at the bottom of the enclosure to provide drainage. Turn the water on from about 8.30 am to 5 pm. When the cuttings have rooted under the mist, they must be very carefully hardened off.  

I have had a Beaumontia creeper for eight years and, although it is growing beautifully, it has never produced flowers. It has had at various times 2:3:2, compost mulch, and water in dry periods, but still no sign of flowers.

Beaumontia is a successful climber but it needs full sun to flower well. You can try giving it ¼ lb (100g) superphosphate over the root area and pruning it after the flowering season. Give it a little more water than you are at present.

I have a single camellia, three years old. In its first year, the leaves were a dark green and very healthy looking, but the buds never opened and just dropped off. Because we have heavy frosts, I moved the shrub to within 3 ft (1 meter) from a south-facing wall. This year the leaves are yellow and the buds still fall off. I fed it with 2:3:2 in autumn. It gets water four times a week and last summer l gave it a thick mulch of pine needles and old farmyard manure. The soil is rather alkaline and has a fairly high clay content. When transplanting the shrub, I dug the hole and mixed one part manure to one part soil to 0,5 part sand.

A south-facing wall is too hot for a camellia. I suggest you move it to an east-facing wall where it will be shaded from midday onwards. When you prepare the new hole, dig a square hole and put 1 lb (500g) of superphosphate well down in the root area, and if you have any well-decayed pine needles, put those around it as a mulch after planting. Plant at the same depth as it was growing before (camellias do not like being planted any deeper). 

When you think the plant has settled down, give it an application of iron chelate at the rate recommended on the container and 2 oz (60g) of magnesium sulfate. I think you are watering the plant too much. Water well once a week from September until January if the weather is dry. You can repeat the iron chelate/magnesium sulfate treatment in three to four months’ time. Sprinkle sulfur around the bush to help make the soil acid, and if you can get compost made of pine needles keep it mulched with that.

I have a variety of shrubs to transplant. How can I move them without harming them?

Not all shrubs can be safely transplanted when fairly large. First, dig the new holes for the shrubs, loosen up the soil at the bottom and add ½ lb (250g) of superphosphate. Water the shrubs well the day before they are to be moved.

Dig them out with as large a ball of soil around the roots as you can manage, and put them in the new holes without delay. Fill in the soil around them, firm in well and water thoroughly.

After that keep the soil damp, but not saturated. Reduce the top growth to compensate for the loss of roots. Spring is the best  time to do the transplanting

I have a lilac bush that is over 15 years old and has never bloomed.

Lilacs like good, rich soil that is slightly alkaline, and they must have plenty of water. They flower best if planted where they get full sun for at least half the day, morning sun preferably. 

Give the bush  250g of superphosphate; put down a generous mulch of compost and water well during dry weather. As a rule, lilacs do not need pruning, but as yours is an old specimen, you could prune it very lightly.

Remove suckers as they appear around the plants. You can transplant the suckers and so increase your stock.

My apricot-colored frangipani, which has been growing in a large pot for the last eight years, has healthy-looking branches and leaves but it has never flowered. What can I do to make it flower?

Give your frangipani two level tablespoons of superphosphate and mulch the soil with well-made compost. Water regularly during dry weather. 

My brunfelsia was planted in a spot in the lawn but never developed in any way. It has now been replanted in a bed but still appears to be dormant in growth. Does this plant need feeding or pruning? Should it be allowed to develop in a separate little place? 

Prune it lightly in winter, give it 2 ½ oz (75g) of the fertilizer mixture 2:3:2, and put down a generous mulch of compost. Water well during dry weather. If the plant does not respond to this treatment, I suggest you discard it and buy another.  

My Australian tea bushes are once again coming into full bloom and I shall be receiving requests from friends for slips and seeds. However, I don’t know of anyone who has had any success in the past. How does one propagate these shrubs?

Small lateral cuttings, 2 – 2 ½ ins (5- 7cm) long, can be taken in autumn; these should be of well-ripened wood or young growths. About the same length can be taken in summer. Prepare the cuttings in the usual way; trim the heels and remove the lower leaves, then insert them in a rooting medium made up of two parts, clean coarse sand and one part peat or leaf mold, with a thin layer of sand on the surface. You can use a rooting hormone. Firm the cuttings in well and water.

Before placing put the pot/s in a polythene bag, put a few short stakes around the sides of the pot/s to prevent the polythene resting on the cuttings. Draw the top of the bag up and inflate by blowing into it, then secure well. Put it in a warm place where it gets plenty of light or dappled shade. When the cuttings have rooted, gradually harden them off, ie, open the bag and gradually remove it, and put the cuttings where they get more light and plenty of air.

When they are growing well, pinch out the tips to encourage bushy growth. Plant out into the garden while still quite small. When raising a number of cuttings, it is easier to place the small pots in a large shallow one and enclose the whole in a large plastic bag.

Tea bushes can also be raised from seed. Pick the seed pods before they release the seed. Sow the seed on the surface of fine soil, mixture of sand and peat and/or acid compost, with a little soil added, and cover with a mere sprinkling of sifted sand. Water from the bottom. Cover the pans with glass and keep them in a shady place until the seed germinates. Prick out into individual pots filled with acid soil, pinch out the tips to induce bushy growth, and transplant into the open while still fairly small.