When to prune hibiscus?

Hibiscus

October 13, 2018

We have about 15 potted hibiscus stationed around the pool in colors red, yellow, pink, light and dark orange. They have grown into small bushes and need to be trimmed in order to store them in the garage for winter. My question: Could we trim them at this time of year. I realize a lot of buds would be cut, but it won’t matter in the garage.

Continue to enjoy the hibiscus while they bloom, and cut back as much as needed when you move them into the garage. I think many of our tropical flowering plants are making a nice late show. As you know they do die back a bit in the garage, so don’t cut them back severely, do that when you move them back outside next spring, and repot.

February 3, 2018

I brought a twisted trunk Tropical Hibiscus into sunroom when the weather turned cool. I have had a terrible time with aphids, over a period of time I have sprayed with dawn liquid & water (four times) I still saw aphids so I stripped off all leaves & sprayed again. Did I kill it?

I doubt you killed it by removing all the leaves, but it sure isn’t happy. I would go ahead and cut the plant back by half. Tropical hibiscus plants bloom on the new growth, and if you keep a plant from year to year, it needs to be repotted and cut back severely before new growth kicks in the following spring. Since it doesn’t have leaves, now is the time to do so. If you allow it to start leafing out on the existing branches, it is going to be weak and leggy and you will have less flowers this summer. After you cut it back, you can take the plant into your bathtub and run the shower over it with tepid water, making sure the water can drain freely. Then move it into a bright, sunny location and see if it doesn’t begin to leaf out. Aphids are notoriously bad swimmers and a nice shower now and then, could do the trick. If you need to make your own insecticidal soap again, try a teaspoon of Murphy’s Oil Soap per gallon of water.

November 18, 2017

Can you identify this plant for me? It has beautiful pink flowers on a plant that is about 9 feet tall. It is blooming now

The plant is a hardy hibiscus commonly called a confederate rose, Hibiscus mutabilis. It dies to the ground in the winter and grows up to 10 feet or more in one season. This particular hardy hibiscus is reliably hardy from central Arkansas south. It only blooms in the fall and the blooms go from pink to dark pink or white to pink in the course of a day.

August 19, 2017

Someone in my house did the unthinkable and threw out Saturday July 15th paper with your article Showy Survivors. I tried going through AR Dem Gazette web site but wasn’t allowed to view it. Is there a way I can view it again? I was mostly interested in how some plants were from the same family as (okra)? For years, I have questioned what the plant is that blooms in road ditches this time of year that looks like okra blooms. I keep your book close by and a huge fan of your column.

I believe it is my understanding that subscribers can also have an online account as well which they should be able to search. If you have problems, you can call my editor Kim Christ at 501-378-3495. The showy plant related to okra is hardy hibiscus with dinner plate sized blooms in pink, red or white.

June 2010

We have several hibiscus plants in our yard and every year the leaves get little holes, almost like filigree. The flowers are not affected but the leaves look terrible and don’t offer the lush green look we wanted in combination with the large flowers. Any suggestions?

The insect in question is called a mallow sawfly. The females lay eggs in the upper surfaces of leaves, near the leaf margin, producing blister-like swellings. When the eggs hatch, the larvae move to the underside of the leaf and begin feeding. The larvae look like caterpillars, but they are actually more closely related to members of the bee family. They can be controlled with Sevin, Rotenone or Imidacloprid (Merit, Bayer Advance Tree and Shrub insecticide). If you don’t control them they can turn the leaves into lace in a short period of time. While this really doesn’t hurt the plants–they come back strong again next year, it is not the most attractive look. The species has up to six generations per year, and adults are active from mid spring until frost. Here is a to pictures of what the insects look like.

June 2010

We have five hibiscus plants in pots on our patio. My husband calls them my babies. Ha! One is a double bloom tree and the other four are regular ones. All different colors. We take them in the garage in winter and prune and put out in spring. This is the third summer we have had two of them and second for the other three. They are growing good and the leaves look great but are hardly blooming. The double bloom tree will have one or two blooms every now and then and one of the others the same. Three are not blooming at all, no buds, but they all look healthy. We have been told several different things to put on them but wanted to ask you. Do they need Phosphorus? We put Potassium { 0-0-60 } and start ‘n’ grow time release {18-6-12 } on them in the spring. Not being gardeners we need help. We live in Cabot and these plants are in full sun.

This is a common complaint from folks who keep their hibiscus from year to year. Keep in mind that these plants bloom on the new growth. If the plants are large and possibly root bound, they won’t grow a whole lot. They can be full of foliage and look healthy, but unless they are growing well, they aren’t going to flower well. If you keep your plants from year to year, I suggest repotting every spring when you move them outdoors and cutting them back by at least one third if not by half. Then fertilize regularly–every week or two with a water soluble fertilizer and periodically with a slow release granular fertilizer. I would go with a complete fertilizer which has ample N-P-K (13-13-13 or 20-20-20) would be fine. Water as needed and they should bloom well. Or you can do what I do and buy new plants that are vigorous every year and get plenty of flowers!

July 2007

I have seen squirrels eating leaves from the lowest limbs of my two hibiscus. Besides getting mad as an old wet hen, – I have moved the pots away from the banisters of my deck, now the pots are on a table with chairs moved out of reach to the pests. They are eating the leaves yet. Will they eventually ruin my plants? They are not blooming as well as they have been although I am careful to keep them watered well. I have seen them get the buds and eat them. What can I do? I do have a large brown rabbit in the yard – but have never seen it on the deck.

Once squirrels find a new food, they continue to feed on it unless you can deter them. They can ruin your hibiscus and keep it from blooming. Several things to try–scare devices, hot pepper sprays, etc. I have had a few gardeners tell me they used Vaseline and hot pepper sauce mixed and applied it to the rim of the pots. When the squirrels sat on the edge of the pots they got the stuff on their paws and licked it then stayed away. Apart from physically barricading your plants, there is no sure fire way to prevent damage–so try a combination approach and see what works for you. Rabbits usually won’t eat anything higher than they can reach, so I think the culprit is the squirrels.

October 2006

I have a hibiscus and a calla lily that are being kept outside, but still in their pots. My question is what would be the best way for them to survive the winter? Should they be planted in the ground, left in the pots and outside or brought inside? Should I continue to water them (since they are still green)?

Tropical hibiscus plants will not survive outdoors in Arkansas, whether they are planted in the ground or in a container. The Calla lily should survive outside, but would do better if planted in the ground, versus staying in a pot. Planted outdoors it will die to the ground after a killing frost. The hibiscus can either be brought indoors for the winter or treated as a houseplant–slightly less water than while outdoors, but do water and give it sunlight. Or it can be protected from freezing in a garage or storage building. In that case, water sparingly. It won’t look perky when you move it back outdoors next spring, but cut it back, and it should bounce back and begin to bloom. If you are going to treat them as houseplants, they need to be inside now.

October 2006

I planted 3 hibiscus plants in my yard this past spring. They are about 3 1/2 feet tall now and really beautiful. How can I keep them from dying over the winter? Will it hurt to cut them back close to the ground…mulch well and cover with a bucket or something? They are not the hardy variety. I don’t know what the winter weather will be like in SW Arkansas….it’s always a surprise. Please advise me. I really don’t want to dig them up if I don’t have to.

If you want them to be alive next spring, and they are the tropical forms of hibiscus, you better prepare them now for the move indoors or into a garage or storage building. (If you live in the northern part of the state, you may have already waited too long!) Tropical hibiscus will not over winter in the ground in Arkansas, even with extra protection. They can be treated as a houseplant, or even stored in the crawl space under your house. If you do plan to have them as houseplants all winter, don’t be alarmed when they start a major leaf drop after the move indoors. Since they have experienced the cold weather we have had recently, the lack of humidity, stable temperature and lower light indoors, will give them quite a shock. You can always do what I do, and simply buy new ones every spring.

June 2006

I received a Hibiscus plant and would like some tips on growing and caring for it. It is a large bush which I will plant outside. I have always heard they are difficult to grow and maintain. Can you provide me with the proper ways of caring for it? It did not have any instructions with it at the time I received it.

I assume you got a tropical plant rather than a hardy perennial type, since those are the more common gift plants. Tropical hibiscus plants can bloom all summer long. The main ingredients for success are full sun, ample moisture and monthly fertilization. You may want to give it a larger pot to grow in to make watering less tiresome, but they are easy plants to take care of. They are not winter hardy, so if you actually do plant it in the ground plan on digging it up and moving it indoors this fall or getting a new one next season.

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A host of hibiscus

When you say hibiscus, most gardeners picture the showy tropical flowering plant that graces many landscapes and patios throughout Arkansas. The flowers come in a wide range of colors and the plants bloom nonstop all summer long. Yet, the tropical hibiscus, Hibiscus rosa-sinensis, isn’t the only hibiscus we can grow in Arkansas.

Hibiscus plants are members of a huge family of plants called Malvaceae or Mallow family, which include okra, cotton and hollyhocks. When we narrow the family down to plants we commonly call hibiscus, we have some annuals, perennials and even woody shrubs to choose from.

Hibiscus rosa-sinensis

Unless you move the tropical hibiscus into a protected location for the winter, Hibiscus rosa-sinensis would be an annual for Arkansas gardens. The flowers last only one day, but provided the plants get ample sunlight, they usually set enough buds that they will continuously bloom all summer up until a killing frost in the fall. They thrive in heat and humidity, but do like regular water and fertilization.

Plants are sold in a variety of sizes including some with braided trunks. The flowers are extremely showy and grow on glossy, green leafed plants. If you do overwinter your plants indoors, be sure to cut them back before moving them back outside next summer. They bloom on new growth and need to be repotted annually and cut back by by half or more each season to encourage new growth. Plants with braided stems should be cut above the braided trunks.

. . .

Hardy hibiscus is the common name given to several showy perennial hibiscus varieties. New plant introductions are constantly being released and today’s perennial hibiscus choices can range from plants that are 3 feet tall to 20 feet tall at maturity.

Perennial varieties usually begin blooming in late June to early July and continue to bloom through early fall. Flower color is usually in shades of pink, red or white, while foliage color can be green or red, but the foliage is much thinner, and hairy compared to the tropical form. Shape of the foliage can vary by species from large oval leaves to palmate leaves. All of the perennial forms thrive in full sun and moist conditions. Although they form woody stems, after a frost all of the perennial forms die back to the ground and do not begin new growth until the soil warms up in spring.

HIBISCUS MOSCHEUTOS

The most commonly sold “hardy hibiscus” is Hibiscus moscheutos with large saucer-shaped flowers. Some of the most popular early releases were Lady Baltimore, Lord Baltimore and Disco Belle, but today there are many more to choose from. They have dinner-plate size blooms with large leaves, but mature size can run the gamut from dwarf to tall. Some have burgundy foliage while most have green leaves. The mallow sawfly is a common pest, turning the leaves into lacy skeletons. It doesn’t affect the plants’ growth, but it can detract from their ornamental attributes.

HIBISCUS COCCINEUS

Hibiscus coccineus is commonly called the Texas star hardy hibiscus. This hibiscus will grow up to 8 feet tall and wide in moist, well-drained soils. The flowers are bright red with distinct five petals, looking somewhat like a star. The foliage also looks quite different from other hardy hibiscus, having narrow palmate leaves reminiscent of cannabis, but it is not related.

HIBISCUS MUTABILIS

The latest flowering hardy hibiscus is Hibiscus mutabilis, often called the Confederate Rose. The plants are not reliably winter hardy in the northern tier of our state, but cuttings can be taken before a frost and they easily root during the winter to be replanted outdoors next spring after the soil warms up. This perennial can grow 10 feet tall or more in one growing season. It doesn’t begin to bloom until late September or early October. There are single and double forms, which open pink or white depending on the variety and change to a deep pink or red by the end of the day. Plants will often have three different colored blooms on them at the same time. The foliage looks like cotton, one of their cousin plants in the mallow family.

HIBISCUS SABDARIFFA

If you have ever had red zinger tea, you have been drinking tea made from another annual hibiscus — the Roselle hibiscus — Hibiscus sabdariffa. Native to Africa, this plant produces small yellow flowers but at the base of the flower is a showy red cup-like structure called the calyx. That is what is used in making tea, jam or sauces, and what makes it an ornamental in the garden. In Florida, the color and the tart taste of the fruit has led gardeners to use them as a substitute for cranberries. There are many recipes for Florida “cranberry” sauce using the calyces. Roselle is easily grown from seed and can be planted outdoors in late April or early May. It will not begin to bloom until late summer into fall, but one plant can produce a copious amount of calyces. Save seeds before a frost to replant the following year.

HIBISCUS SYRIACUS

Hibiscus syriacus is a common deciduous shrub commonly called althea or rose of Sharon. These old-fashioned shrubs have made a comeback in recent years with many new introductions. Flower color can range from white, to pink, purple and apricot, with some bi-colored blooms. Flowers can be single or double formed. Flowering typically begins in late May to early June and continues until frost. They do best in full sun to partial shade and are tough plants in the garden. They can be pruned to whatever size your landscape desires. Many have multiple trunks, but they can be trained to a single trunk as well.

HIBISCUS CANNABINUS

An important commercial species is Hibiscus cannabinus or Kenaf. Kenaf is a giant hibiscus native to southern Asia grown as a fiber and oil crop. It is capable of growing up to 20 feet in one year under ideal conditions. Development and commercialization of kenaf and various kenaf-based products in the United States started in the 1940s. More USDA research and industry interest was triggered by high newsprint prices in the late 1970s. Today, most of the world’s kenaf is produced in India and China, but research and development is ongoing in Texas, Mississippi and other southeastern states with an emphasis on newsprint. In 1970 kenaf newsprint was produced in Pine Bluff at the International Paper Company’s mill. The foliage looks a bit like cannabis, thus the species name H. cannabinus.

Hibiscus plants can add a lot of color and interest in the summer through fall gardens. Whether you want a permanent shrub, a perennial plant that dies back to the ground or an annual with long-lasting color, you will find many choices in the hibiscus family.

Photo by Special to the Democrat-Gazette/JANET B. CARSON
The hardy hibiscus has a woody stem that will die back at frost but the plant emerges again when the soil warms in spring. Photo by Special to the Democrat-Gazette/JANET B. CARSON
Hardy hibiscus blooms usually are shades of red, white or pink, such as this vibrant fuchsia. Photo by Special to the Democrat-Gazette/JANET B. CARSON
Tropical hibiscus like regular water and fertilization and will not survive the winter outdoors. Photo by Special to the Democrat-Gazette/JANET B. CARSON
Hardy hibiscus Texas star’s blooms have five distinct petals. Photo by Special to the Democrat-Gazette/JANET B. CARSON
Confederate Rose can grow 10 feet in one growing season, and blooms change color during the day. Photo by Special to the Democrat-Gazette/JANET B. CARSON
A larvae of the mallow sawfly feeds on hardy hibiscus leaves. Photo by Special to the Democrat-Gazette/JANET B. CARSON
Aphids make themselves at home on a hibiscus bud. Photo by Special to the Democrat-Gazette/JANET B. CARSON
The calyx of the Roselle hibiscus is used to make tea, jam and sauces. Photo by Special to the Democrat-Gazette/JANET B. CARSON
Rose of Sharon, also called althea, is an old-fashioned perennial shrub that performs well in Arkansas.

HomeStyle on 07/20/2019

I sure hope that you can help me. I have a tropical hibiscus. It keeps dropping its flower buds. It did have a lot of aphids, but I sprayed it regularly and now the bugs seem to be gone. However, the buds still drop. Can you give me some suggestions to help my poor hibiscus?

Tropical hibiscus is an excellent plant for adding bold color to your garden or patio.

In my garden, I have freezing winter temperatures so I treat these exotic beauties as annuals. However, many people who live in similar climates want to save their hibiscus, so they simply bring the plant indoors for the winter.

Hibiscus flower buds are very sensitive. Stress from too much or too little water, over fertilizing or insect infestation can cause buds to drop before opening. Double flowering varieties are more susceptible to bud drop.

It may be possible that your hibiscus is still recovering from the aphid infestation and subsequent treatment. To lessen the shock it is important that plants are well hydrated when applying pesticides and that the treatments occur either in the early morning or late afternoon when temperatures are below 80 degrees F.

If the problem persists, check your watering. Hibiscus will not tolerate wet feet, so be sure that the soil drains well. When growing in containers a soilless potting mix is preferable. These plants also suffer when allowed to dry out in hot weather. A 2 to 3 inch layer of mulch will help keep the roots cool and retain moisture.

Hibiscus are heavy feeders and should be fertilized every 7 to 10 days during the spring and summer with a product that is high in phosphorous. For potted plants use a water-soluble 20-20-20 blend. Slow release fertilizers are also recommended.

Hibiscus thrive in full sun but for the best bloom production give them shade during the hottest part of the day if your garden experiences temperatures above 90 degrees F.

And if you want to overwinter your hibiscus, move your plants indoors before temperatures fall below 50 degrees F.

Tips For Pruning Hibiscus Plants & When To Prune Hibiscus

Hibiscus plants thrive on attention. Pruning hibiscus is a great way to give these plants just what they need. Pruning helps stimulate budding on new shoots. It also rejuvenates the plants after their long winter nap while encouraging them to maintain an attractive appearance and healthy, vigorous growth. Let’s look at when to prune hibiscus and the best techniques when pruning hibiscus plants.

When to Prune Hibiscus

When to prune hibiscus usually depends on where you live. However, most hibiscus pruning occurs during spring. For the most part, hibiscus plants can be lightly pruned in late summer or early fall, but no hibiscus pruning should be done during late fall or winter.

One of the downsides to waiting later in the season to prune is that plants may not develop as many branches, and they will put out fewer blooms. Therefore, it is oftentimes better to prune dead or weak growth entirely after the plants beginning sprouting in spring.

In fact, spring should be the only time for complete cutting back. Pruning hibiscus plants entirely helps rejuvenate them for summer blooming. Branch tips can be pinched, or tip pruned, throughout the season, however, to encourage bushier growth.

Hibiscus Pruning How To

Before pruning hibiscus, make sure your pruning shears are sharp and clean, preferably sterilized with alcohol gel, to prevent the spreading of any disease from affected branches. When pruning hibiscus plants, they should be cut about a third of the way back, leaving at least two to three nodes on the branches for new growth to emerge. These cuts should be made just above the nodes, leaving about a quarter inch. Remove any weak, diseased, or dead growth, as well as crossing or leggy branches. Branches that are growing toward the center of the plant should also be removed.

Once temperatures have sufficiently warmed towards the end of spring, you can help give blooms an extra boost by increasing the amount of fertilizer.

An easy way to diagnose your problems! We have endeavoured to supply answers to the questions most asked about hibiscus that we receive each year. Some specific problems cannot be solved without inspection of the plant, whilst others are readily rectified.

Learn to observe your plants – accurate descriptions of problems assist in recommending treatment, many symptoms being similar but requiring different treatment. We sincerely hope that our answers lead to better hibiscus!

Pests and Diseases
Q. My plants are not flowering. Although they look very healthy, there is no sign of any buds!
A. Hibiscus require full sun to produce

good flowering wood, so the plant could be growing in a shady position, otherwise the plant has been infested with tip‑borer. This very small borer attacks the growing tips in spring, automatically tip‑pruning the plant. The loss of the growing tip at this time prevents the green wood in maturing into flowering wood. Spray regularly during spring with Endosulfan or Carbaryl.

Q. Although I have been keeping it moist, my plant is wilting.

A. Sounds as though you may have kept it too moist, and it is suffering from either root‑rot or collar‑rot. It is best to discard the plant and improve the drainage in that position, and replace the soil before replanting.

Q. My plant suddenly turned yellow and lost all its leaves.

A. This plant has received a severe shock possibly caused by spraying with either Malathion or Lannate or other systemic insecticide. Spraying on a very hot day, using too much white oil, overfertilising or not watering the fertiliser in properly after application are possible causes. Cultivating too close to the main stem, borer infestation or collar‑rot may also be to blame.

Q. One large branch on my plant has suddenly died.

A. Your plant has borer. Cut out the affected parts immediately, and next pruning time, cut the plant back very hard and drench the stems with either Chlordane or Dieldrin.

Q. How do I get rid of the Hibiscus Beetle?

A. The problem with this beetle is that it penetrates the buds before they open, making it safe from spraying materials. The general rule is to apply a follow‑up spray about two days later. The beetle becomes immune to spray very quickly, therefore rotation of sprays is necessary. Use Endosulfan, Carbaryl, Diazinon, Mesurol (Methiocarb) alternately for best results and Dieldrin and Lebaycid occasionally. A suitable wetting agent aids in applying the spray to give better coverage. Both Diazinon and Mesurol will cause slight discolouration in blooms for several days after spraying. Spray when the first signs of beetles are evident, thus preventing heavy infestation.

Q. When is the best time to spray?

A. Early morning, after the dew is off the plants and the flowers are open is the best time for spraying. Never spray your plants in the middle of a hot, sunny day. Be sure to water your plants a day or two before you spray them, since wilted plants are more likely to be injured. If a plant is injured by spraying, its leaves will turn yellow and fall off (over a period of several days). Malathion and Lannate are both likely to cause injury and should not be used on hibiscus.

Q. Some of my plants have yellow, rusty spots on their leaves.

A. This is Alternaria and it usually attacks plants that are deficient in fertiliser during periods of high humidity and wet weather. Fertilise the plants and spray with either Zineb or Benlate.

Q. The foliage of my plants has become malformed, stiff, twisted and deeply serrated and the flowers are like plastic or cardboard.

A. This is phytotoxicity and it is mainly caused by hormone weedicides, usually 2‑4‑D or 2‑4‑5‑T. Care must be taken when using these toxic substances anywhere near hibiscus. Systemic insecticides used regularly or at stronger‑than‑recommended rates can also cause problems with plants. The plants will eventually grow out of it. Hard pruning in spring usually helps. Cases of weedi‑ toxicity have been recorded when neighbours have used these sprays and the slightest wind has carried the drift onto plants.

Q. Something is eating my plants!

A. Before a cure can be found, the cause of the problem must be identified. Caterpillars and grubs leave small, round droppings where they have been feeding. Check for these and spray with Endo‑ Carbaryl or Dipel. Snails and slugs usually leave their silver trails behind, and often congregate under branches close to ground level. They are always active on dewy mornings. Spray or bait with Mesurol (Methiocarb) or Metaldehyde. Grasshoppers also feed upon hibiscus look for large holes in leaves that have rough edges. Grasshoppers are usually easily visible and are best removed by hand as spraying is a little ineffective unless actual contact is made.There have also been cases of plants being eaten by some unknown marauder, and these have been traced to rabbits, deer, possums and the odd kangaroo or wallaby has also been known to try hibiscus leaves.

Q. How do I get rid of ants?

A. The answer to this is get rid of the reason why ants are on your plants and this is usually because they are attracted to the honeydew excreted by aphids. Endosulfan, Diazinon or Lebaycid may be used for this. Sometimes ants are attracted by the nectar that forms in the base of some flowers. A light application of Chlordane around the base of the main stem will deter them in this case.

Q. Can I use insecticide dusts on my plants?

A. Yes, in fact many people believe the dusts have a better residual effect than liquid insecticides.

Q. My leaves are being eaten by a caterpillar, because I can see its droppings yet I cannot see any?

A. Have a look in the soil just under the plant and you will most probably find the culprit‑Army Worm. They feed at night and during the day bury themselves in the soil. They are usually solitary and are best disposed of by hand once found; however, saturation of the soil with Endosulfan will control them.

Q. My plants develop black spots and markings on the leaves, particularly in cooler weather.
A. This is a fungus that attacks some varieties of hibiscus more than others. Healthy plants resist infection better than unhealthy ones so fertilising helps, as does early applications of Benlate or Zineb.

Q. My leaves are curled and twisted and the flowers not as vibrant.

A. Your plant appears to have developed a virus which may spread by the use of infected vegetative parts for propagation and by insect vectors such as aphids and leaf hoppers. Severely infected or damaged plants should be destroyed and replaced with healthy plants, and sterilisation of grafting and pruning implements that have been used on suspect plants is a commonsense practice. Q. Every winter some of my plants die back.
A. This is a fungus infection known as black splash. The disease manifests itself by elongated, dark‑brown to black areas on the stems or branches of hibiscus. These areas are usually sunken, and as they grow they join and merge, eventually encircling the branch, causing it to die. Cut off and burn the affected portions. A spraying of Benlate will often help in controlling black splash.

Q. My leaves are becoming crinkled.

A. Always check on the undersides of leaves for aphids. Often they have done considerable damage before they are detected. Aphids usually are the cause of crinkled leaves. Use Endosulfan, Diazinon or Lebaycid for effective control.

Fertilising
Q. My buds are dropping off.

A. There are several causes of bud drop and any one or a combination of several of them may cause the dropping of buds before they open. Many people are of the opinion that some insect snips off the buds as they appear to be cut cleanly at the break. This is not so. Hibiscus simply jettison buds when they are under stress, and they are put under stress when they do not have enough water or food. Changes in weather and severe infestation of Hibiscus Beetle may also cause bud‑drop. Ensure that your hibiscus has regular watering and suitable fertilising. Excessive amounts of nitrogen in some fertilisers have been known to trigger off bud drop. Overwatering can often leach some essential nutrients from the soil. Mulching helps conserve moisture and nutrients in the soil resulting in more flowers. Hibiscus should never be allowed to dry out in the flowering season or bud drop will occur. Changeable weather during flowering time may also cause bud drop, particularly when there is a large difference between the minimum and maximum temperatures. Heavy infestations of the Hibiscus Beetle will often cause bud drop and regularly spraying is required to combat this pest. Sometimes certain varieties carry a bud dropping characteristic and when hybridised with other varieties, the progeny may have this undesirable trait. The hybridiser should consider this factor when selecting parent plants. Some varieties are notorious bud droppers, and full, heavy doubles are more likely to drop buds than other types.

Q. My foliage is going brown around the edges!

A. Either too much fertiliser has been applied or else the plant was not watered well before and after applying fertiliser. Regular watering will break down the fertiliser more rapidly, and any excess fertiliser still around the plant should be removed.

Q. How often should I fertilise?

A. Hibiscus are gross feeders and require regular fertilising particularly during the flowering period. Nutrients are leached from sandy soils much faster than heavier clayey soils, therefore such soils need fertiliser applied more often. In sandy soils a suitable fertiliser should be applied about every three weeks. In heavier soils every four to five weeks should be sufficient. At the end of the flowering season a well‑balanced fertiliser should be applied to carry the plants through winter. This same fertiliser should be applied after pruning. The regular applications of recommended fertiliser should begin again in late spring as the first buds appear.

Q. What is the best fertiliser?

A. Nitrophoska red, Aboska 27, Nitropep and Redchip are all brand names of suitable fertilisers for hibiscus. However, these are not available everywhere and therefore a fertiliser with an N.P.K. of around 13.13.21 or similar should be used. The high percentage of potash is necessary for continued production of blooms. Consult your local nurseryman to find a suitable fertiliser. Avoid foliage fertilisers with high nitrogen concentrations and slow‑release types.

Q. Do hibiscus like manure?

A. Yes. Any kind of animal manure is beneficial and provides the organic matter necessary to keep plants healthy. Hibiscus benefit from dressings of manure applied about every five to six weeks throughout the flowering season.

Q. Will hibiscus tolerate lime?
A. Yes, although hibiscus prefer a pH of around 6.5 they do well in soils with pH readings from 5.5 to 7.8. When the pH level of the soil falls below 5.5 applications of lime are required to lift these levels to a more suitable one for hibiscus. Regular dressings of manure may also alter the pH levels of soil. In this case a light dusting of lime once or twice a year is beneficial.

Q. Do hibiscus like foliage fertilisers?

A. All fertilisers are manufactured to certain requirements, and should be used according to your needs. Some foliage fertilisers are high in nitrogen and promote rapid growth in young seedlings and cuttings; however they may cause bud drop on large flowering plants by causing too much growth. Others are more balanced and are ideal to use. Always read the label before applying, thus avoiding disappointment.

Q. Can I use poultry manure on hibiscus?

A. Yes, particularly during the flowering period.

Q. Should I mulch my plants?
A. Yes, mulching is most beneficial in conserving both moisture and nutrients and helps in keeping weeds down. Mushroom compost is an ideal mulch; however there are many materials one can use, and some of these are available more readily in some areas than others.

Q. My plants keep going to leaf.

A. Your plants may not be getting sufficient sunshine for the wood to harden into flowering wood, or else you are using a fertiliser with too much nitrogen. There are a few varieties of hibiscus that flower on older wood, and when these are pruned they tend to produce a lot of foliage until such time as the wood throws out the short spurs from which most flowers are produced on those varieties (e.g. ‘Wilder’s White’ H. arnottianus).

Q. My leaves are turning yellow with green veinings.

A. You have a deficiency problem. Most probably it is iron. Use chelated iron or GU 49 iron. Apply a complete fertiliser and dressing of manure.

Q. What about compost‑can I use it on my hibiscus?

A. Yes, a compost heap helps return to the soil what the plants are taking out. Ensure that the compost is well broken down before application or this process may take some of the available nitrogen from the soil. A good mulching several times a year is most beneficial.

Q. How do I apply potassium for better blooms?

A. The use of potassium nitrate to improve the quality of hibiscus blooms is recommended during the flowering period. Use at the rate of V2 cup to 20 L water and apply one cup of this solution to each mature plant. Potassium nitrate is also available in pelleted form and may be applied dry. Remember when applying either dry or in solution form you run the risk of burning your plants unless you use very small amounts at any one time, and water well before and after application. Planting
Q. Can I grow hibiscus in clayey soils?
A. As long as good draining is provided, hibiscus will grow in heavier soils. Where the subsoil is suspect it is a good idea not to dig into this for planting, but to raise the level of your garden bed sufficiently to allow for the drainage. Gypsum helps in breaking down these soils as does the addition of composts and manures.

Q. My plants in the lawn don’t do too much.

A. If you are to grow hibiscus or any other shrub for that matter in a lawn, then you must provide an adequate area free of grass where the plant does not have to compete for food and water. Grass tends to take all the water and fertiliser away from plants and virtually starves them to death. The more one waters and fertilises the more the grass grows. Provide an area about 750 mm (30 in) wide around your plants or better still make a good garden bed and grow your plants away from the grass.

Q. What depth of soil is necessary to grow hibiscus?

A. That depends on the size of hibiscus you want to grow! Most growers prefer to grow the smaller plants simply because they can fit more varieties in. Naturally you cannot grow a 6 m high shrub in half a metre of soil. You can, however, grow very good hibiscus in only 300 mm (1 ft) of soil as long as they are the lowergrowing types. In some areas where rocky outcrops restrict the depth of soil excellent specimens of hibiscus are to be seen. It’s a little like growing plants in pots, as long as you keep the plants well watered and fertilised success is ensured. Where the depth of soil is limited care should be taken to never allow the plants to dry out and lose condition.

Q. What is the best position for hibiscus?

A. Full sun all day and protection from cold winds in temperate areas. Partial shade and shelter from strong winds in tropical areas. In glasshouses or indoors in very cold areas.

Q. Will hibiscus do well in very sandy soil?

A. Yes, in fact they prefer sandy soil as long as liberal amounts of good organic material capable of retaining moisture and nutrients are added. Usually more fertiliser is required throughout the season and mulching is necessary during summer, as is plenty of water.

Q. What is the best time for planting?

A. Here again it depends on your area. It is not advisable to plant hibiscus during winter in temperate zones, and although they may be planted the rest of the year late spring and summer are best. In tropical areas they may be planted all year around. Hibiscus syriacus and other cold‑tolerant species may be planted during winter when they are dormant.

Is it dead? That’s the question I frequently hear in relation to one particular shrub. It’s a beauty that you might have seen on holiday in the Mediterranean or the Caribbean – or at least you might have seen its near relation.

Hibiscus is not that tricky to grow, provided you have a warm, sheltered, sunny spot in well-drained soil. But it is rather late coming into leaf – hence that frequently asked question.

It may be as late as June before a hibiscus starts to unfurl its bright green foliage, but from then on it shows its true worth as a late-flowering shrub.

The species that grows in the warmer countries is Hibiscus rosa-sinensis, which is too tender to grow outdoors in the UK. Our winters would rapidly see it off.

But Hibiscus syriacus is altogether tougher and is available in a wider colour range than its softer counterpart. ‘Blue Bird’ (or ‘oiseau bleu’ if you are feeling continental) is a rich lavender blue, ‘Red Heart’ is white with a pronounced crimson “eye”, and the favourite ‘Woodbridge’ is deep rose pink with a mauve “eye”.

The habit of these hibiscus shrubs is upright and fairly stiff, so they need nothing by way of support. Nor do they need much pruning, since they are relatively slow growing and unlikely to grow so large that they become a nuisance – not before many years have elapsed at any rate.

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Water

During the growing season, water regularly, and ensure drainage is good. Mulch the surrounding area with organic mulch, straw, hay or sugarcane, ensuring it doesn’t touch the stem. This will help keep the roots cool and moist in summer.

Feed

These plants respond well to fertiliser. Choose one that encourages blooms, and is high in nitrogen and potassium, such as Yates Thrive Soluble Flower
& Fruit Plant Food or Miracle-Gro MaxFeed Flowers & Blooms Soluble Plant Food. You can also add a fish emulsion or seaweed extract to this feeding mix. Apply before and throughout the growing season (August through to March) as this will help intensify bloom colour and promote healthy growth.

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Pests

Check plants for the hibiscus flower beetle. These tiny black insects burrow their way through flower buds and foliage, leaving gaping holes. Use a systemic insecticide, such as Yates Confidor or Defender MaxGuard to control infestations.

Maintenance

The best time to prune evergreen types is at the start of the growing season or when the last frost has passed – usually in September. They flower on new season wood, as do the deciduous types, which should be pruned in winter. Prune just above a bud and remove any weak or dead branches. If left unpruned, hibiscus shrubs will become scraggy and shapeless, with fewer flowers and smaller, duller blooms. Prune off one-third of the plant to help rejuvenate tired-looking plants.

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