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14. Questions and Answers

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.

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.

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.

 Q. When can I transplant a hibiscus?
A. The best time for transplanting is just after pruning in the spring. Plants that are cut back are much easier to handle at this time. Generally hibiscus will transplant at any time other than late autumn or winter. Always treat plants with a little Hormone Formula 20 after transplanting for best results.

Q. Will hibiscus grow under trees?
A. They will, grow and survive under trees but they will never flower or reach their potential unless planted in the full sun. The trees would compete for food and moisture, resulting in stunted plants. In tropical areas plants under trees are best if left in pots.

Q. Can I transplant a large hibiscus?
A. Yes, but the question arises is it worth it? Large plants may require a lot of manpower to move them successfully, and take a long time to recover. This time could be better used by encouraging a new, healthier plant to vigorous growth to act as a replacement. The improvement in modern hybrids suggests that some older plants are best replaced with better varieties.

Q. How close can I plant hibiscus?
A. This depends entirely on which varieties you are planting. Some of the lowgrowing varieties can be planted as close as 60 cm (2 ft) apart; medium growers about 1 to 1.3 m (3‑4 ft) apart and tall growers around 1.4 to 2 m (4‑6 ft) apart. Space must be allowed to fertilise and mulch, to keep the plants in tiptop shape.

Q. I have just taken out a large old plant. Can I plant another in the same position?
A. You can, provided that you replace the old, burnt‑out soil with fresh, rich material. Plants take certain trace elements from the soil, and when plants of the same species are planted in the same spot they rarely do well unless the soil has been completely replaced or worked over thoroughly.

Q. How long can I keep a plant in a pot?
A. This depends on the type of hibiscus and size of pot. Naturally a slow, lowgrowing variety will stay in a pot a lot longer than a more vigorous one. The rule is they can stay in a pot until such time as they begin to become unproductive and lose condition. Most plants will stay in a 45‑50 mm (18‑20 in) pot for about five to six years.

Q. My plants in pots are not doing well.
A. This could be caused by a number of things ranging from bad drainage or position to incorrect potting mix. Check
these things first, particularly if you have used general all‑purpose potting mix as this is sometimes not suitable for hibiscus.

Q. What is the best size pot to use?
A. A 45‑50 mm (18‑20 in) pot is ideal, however plants may be started in much smaller sizes and gradually increased until this size is reached.

Q. What is the best pot for hibiscus?
A. This entirely depends on your choice of material. Hibiscus tend to do well in pots made from various materials, however it is important to keep in mind that cement and terra‑cotta containers dry out much faster than plastic ones, or ones made of wood. Hibiscus do prefer the normal basic pot shape, where the pot diameter is almost the same as the pot height. They do not do as well in tall 'Ali Baba' type pots.

Q. Can I plant a small hibiscus directly into a large pot?
A. Of course. It may even mature more rapidly than if kept in a smaller container, however a small plant in a large pot sometimes looks odd, and it is not encouraged for this reason only. Remember to fight the impulse to plant a few annuals or other plants to fill in while the hibiscus is growing. Too often these plants take over and smother the hibiscus.

Q. Do pots need raising off the ground?
A. Pots raised off the ground dry out rapidly, particularly in windy positions and plants may lose condition. Pots with bottom drainage if left on a smooth surface can block up easily, therefore it is a good idea to raise the pot about 6 mm ( 1/4 in) to allow for better drainage without causing the plant to dry out excessively. A small section of flat fibro is ideal for this. Pots with side drainage do not need raising.

Q. How much drainage do I place in the bottom of a pot?
A. Good drainage is essential to maintain plants in top condition. After a plant has been in a pot for several years the drainage holes tend to clog. For this reason plenty of drainage is required when planting hibiscus in pots. Roughly one‑quarter the height of the pot should be used for drainage material. Old, broken tiles or pots, coarse clinker ash, and rough pebbles may all be used for drainage and covered with a layer of ashes or gravel which will act as a filter to prevent soil blocking the holes. Do not block off the drainage holes with material; they have to be free to allow the passage of water.

Q. How often do I water and fertilise plants in pots?
A. A good watering every second day should be sufficient for most plants, depending on the weather. This regular watering tends to leach out the essential nutrients more quickly than if the plants were in the ground. Therefore the fertiliser has to be applied to the plants more regularly than if the plants were in the ground. Fertilise about every two to three weeks throughout the flowering period.

Q. When is the best time for potting and repotting hibiscus?
A. Any time except winter is all right for potting and repotting, although mid to late spring would be the ideal time. The plants have been pruned and are easier to handle then. Old, neglected plants can be pruned heavily and root pruned and repotted into fresh soil in the spring.

Q. What is the best soil for hibiscus planted in pots?
A. Every nursery will tell you that hibiscus will do well in the particular soil mix that they are selling, and sometimes this is true; however from past experience it is best to get soil from a specialist grower or mix your own. Hibiscus like a free‑draining, open mix with a good amount of humus. Two parts sandy loam, one part peat moss, one part cow manure or mushroom compost and one part coarse river sand makes an ideal mix for plants in pots that are to be left outside all the time. If you are in a colder area it is better to use only one part sandy loam, particularly if your pots are to be moved indoors during winter. It is best to avoid pre‑packed soil mixes that are based on composted sawdust.

Q. What is the best position for hibiscus in pots?
A. The more sun hibiscus are given the better, therefore they will do well in any position in the garden, be it a sunny patio or deck, courtyard or wall, providing full sun is provided. One of the main advantages of hibiscus in pots is that you can make them mobile, following the sun around. This is very useful during winter when these plants like that little extra warmth.

Q. What is the best time to hybridise?
A. Even before‑the blossom opens, the stigma pads are receptive to pollen, therefore early in the morning is the best time.

Q. How does one hybridise?
A. Hybridisation is simply crossing two plants together to produce progeny that hopefully will have the desirable traits of both parents. It involves dusting the male portions of flowers (pollen) onto the female part of the flower (stigma or pistil). In hibiscus this is easy as the pollen sacs are a cluster of yellow anthers prominant on the staminal column, and the stigma is recognised by the five stigma pads at the tip of the column. Each of the five stigma pads must be dusted with pollen either with a soft brush or the bloom of the pollen parent may be picked and the pollen applied directly.

Q. What time of year is best for hybridising?
A. Some growers hybridise most of the year around; however mid‑autumn to early spring is best. In cooler weather, the humid and foggy days are ideal. High temperatures dry out or inhibit the pollen so that it is not viable.

Q. How deep should I plant seed?
A. Make a depression the size of a finger tip and 6 mm (%4 in) deep in the soil mix, then cover the seed with more mix.

Q. How long do the pods take to ripen after hydridising?
A. The pods may take anything from forty to seventy days. They must be watched carefully as they begin to ripen, lest they burst and the seed is lost.

Q. What do I sow seed in?
A. There are numerous seed mixes to use. Some growers have good results just using compressed fibre blocks. A mixture of sand and peat and ground‑up sphagnum is ideal. Vermiculite and peat, perlite and peat, milled mixture of sphagnum and vermiculite or sterile soil may be used as well. Sometimes it is a good idea to try several mixes out and use the one that gives the best results in your area.

Q. How long does it take seedlings to bloom?
A. Most seedlings will bloom in 10 to 14 months, provided that they are not cut back as this delays blooming. Plants grown in full sun will flower much quicker than those grown in shaded positions.  

Q. When do I take cuttings?
A. Hibiscus may be grown from three different types of cuttings: tip cuttings which are taken in summer; firm wood cuttings which are taken in autumn; hardwood cuttings that are taken in late winter or early spring.

Q. What do I put the cuttings in?
A. Most cuttings do best if placed in small individual pots. A mixture of sand and peat, perlite and peat or washed river sand should be used.

Q. When can I graft?
A. The best time for grafting is during summer and autumn using the side graft method. Tip or cleft grafting is better when done in the spring.

Q. Can I graft several varieties on to one understock?
A. You can, but unless you only have limited space to grow just one plant it is not recommended. After a while one variety will begin to dominate the others, reducing their vigour. Two varieties on the one understock is sometimes very interesting.

Q. What understock is best?
A. This depends on your area. (Different growers use different understocks in different areas. `Ruth Wilcox' (`Albo Lacinatus') or `Wilders White' (H. arnottianus) are the best overall; `The President' and `Pride of Hankins' (`Landersii') are good for some areas.

Q. When do you cut the plastic tapes from your grafts?
A. Once you are sure you have a good union formed between your understock and scion, you should cut the tape to prevent constriction. It is best to do this eight to ten weeks after grafting.

Q. When is the best time to sow `Southern Belle' seed?
A. The best time is in early spring. `Southern Belle' will usually flower within a season in warm districts.

Q. When do you cut off the top part of the understock from a side graft?
A. This varies, however the general rule is when the leaves on the scion become mature enough to function properly and support growth for that plant.

Q. How long do I leave cuttings before they take root?
A. This again depends on the area where the cuttings are. Most cuttings should strike within eight to ten weeks. It is better to discard cuttings that take longer than, say, fourteen weeks to strike as they generally don't produce strong plants.

Q. How long should cuttings be left before they are potted?
A. Once cuttings are rooted and the root system is sufficiently strong the earlier the better. Cuttings progress much more rapidly once planted in good soil. Cuttings left in propagating materials lose condition if left too long.

Q. Someone said to throw a plastic bag over my cuttings. Is this right?
A. Cuttings strike better if kept in a warm, humid atmosphere, particularly tip and medium wood cuttings. Covering them with a plastic bag is an excellent way to provide this atmosphere. The plastic may be removed regularly to prevent a buildup of fungus diseases which also proliferate under these conditions.

Q. My double flowering hibiscus has turned single.
A. Hibiscus blooms are governed by the weather conditions and produce their best blooms during summer and autumn. Flowers produced outside these times are sometimes out of season and we have doubles reverting to singles and flowers getting smaller in size and deepening in colour. The flowers will return to double as the new season approaches.

Q. My flowers only last a day then drop off!
A. The hibiscus flower only lasts a day, although many new hybrids have been bred which now last longer, even up to three days. Do not think of this as a disadvantage; remember that many plants bloom but once a year for only about two to three weeks and although their flowers may last longer, they are often damaged by wind, rain and insects and one has to wait another year for a repeat performance. With hibiscus a new flower replaces the old one the next day; a guarantee of fresh flowers all the time over seven or more months a year,'

Q. My hibiscus was red with white splashes, now it is only red!
A. Another case of flowers out of season. The white spots will reappear as the warm weather returns. Most hibiscus with spots or splashes of different colours lose these in the off season.

Q. My blooms sometimes open with rolled edges!
A. This is caused by the early morning sun hitting the flowers when they are covered with dew. It is often caused also by overhead watering during the heat of the day.

Q. My flowers sometimes miss a petal!
A. The flowers don't actually miss a petal, they will still have five, but some varieties, particularly the semi‑doubles with large exaggerated staminal columns, often produce these blooms. This is called crippling and it is just the variety that bunches the petals around the staminal column causing the gap in the petals.

Q. How do I transport blooms without damage!
A. It is very hard to transport blooms that have already opened, therefore the trick is to pick them in the bud stage as they are about to open and place them in paper cones or drinking cups. The buds when removed from the cups will open spontaneously. Do not place them in styrofoam containers since petals will often stick to them and are torn on removal. Buds may also be packed tightly in boxes, where again upon removal they will open.

 Q. Can I make my blooms last longer?
A. Hibiscus blooms will not last any longer whether they are left on the bush or picked, whether they are placed in water or not, and they do not usually last any longer when placed in a refrigerator. The refrigerator will however postpone the opening of buds for a day or so, but the flowers themselves will last no longer once they open. Select varieties that last longer for a start. Many new hybrids last considerably longer than older varieties.

Q. How often should I water?
A. A good watering twice a week in the middle of the season is more beneficial than a light watering every day. Naturally plants may require more watering to keep their condition during a very hot dry spell.

Q. When is the best time to water?
A. Late afternoon or twilight is best. Avoid watering during the heat of the day.

Q. Is a sprinkler system good to use for hibiscus?
A. Sprinkler systems are very good, however overhead watering may sometimes damage buds. Care must be taken to observe the time of day they are to be used. Later afternoon is best.

Q. How much water should I give my plants?
A. Too much water causes as many problems as too little. Maintain a good moisture level in your soil without it remaining soggy. Too much water also leaches valuable nutrients from the soil. A good soaking equivalent to 25 mm (I in) of rain about twice a week would be ideal.

Q. Is trickle feed irrigation any good?
A. Yes, a number of growers have had excellent results using this method of watering.

Q. When watering should I hose the whole plant or just the soil?
A. It is better to apply the water to the soil most of the time, however a good hosing of the foliage every now and again helps keep the plant clean. Dust and grime builds up on the leaves in some areas and regular hosing will remove this. Near the coast watering of the foliage after a salt‑laden wind is recommended to reduce build up of salt on the foliage.

Q. When should I prune my hibiscus?
A. The best time for pruning the rosa‑sinensis types is spring; H. mutablis and syriacus varieties should be pruned in winter.

Q. How much do I cut from my plants when pruning?
A. Most hibiscus relish being cut back about one‑third all over. There are a few exceptions of course which do better when left unpruned. Plants that are very woody can be cut back half way or more to induce new, healthy wood.

Q. My weeping hibiscus isn't weeping!
. The weeping or waterfall hibiscus `Ruth Wilcox' (`Albo Lacinatus') is one hibiscus that does better when left unpruned. If it is pruned each year it produces nice long, straight canes that give very few blooms, if left unpruned these canes begin to weep and produce smaller laterals which become covered in flowers. A severe pruning every five to six years will maintain this variety in good condition.

Q. My plants are very straggly!
A. They require pruning to maintain a nice rounded habit. Remove all lower, straggly branches, and trim the plant back one‑third in spring.

Q. Why do you have to prune?
A. There are several reasons for pruning, the most important one being that pruning promotes strong healthy growth which in turn produces the best flowers. It is also used to remove old, decayed and diseased wood, and to keep the plant in a desired shape.

 General Issues
Q. How long do hibiscus live?
A. This depends a lot on its position and care. Most plants begin to lose condition around twelve to fifteen years, however there are many specimens well over fifty years old around, particularly of the early hybrids.

Q. My grafted hybrid hibiscus was a large yellow variety that was rather slow, now it is growing vigorously and producing small pink flowers.
A. The understock has taken over. Hybrid hibiscus are grafted onto stronggrowing, hardy understocks, and sometimes if an eye has been left, this stock begins to grow and if not cut off early it will completely dominate the grafted variety. Usually these understocks have a different leaf which makes identification easier in the early stages.

Q. My hibiscus don't begin to bloom until late in the season.
A. They are probably not getting enough sun. Check the sunlight situation first; if they are getting full sun then more than likely something has happened to your growing tips‑possibly damage by tip‑borer. If that's the case spray regularly during spring with Endosulfan.

Q. Why are Hawaiian hibiscus not as hardy as others?
A. Hardiness depends entirely on the variety. Most modern hybrids are loosely called Hawaiian hibiscus when many of them have been bred in Florida or Australia. Because they are complex hybrids, it is true that some of them may have lost their vigour through years of hybridisation, in an effort to produce more spectacular blooms. In most cases this lost vigour has been restored by grafting these varieties on to hardy rootstocks making them perform well. Some modern varieties however are just as vigorous and hardy as some of the old ones.

Q. My `Southern Belle' type of hibiscus keeps breaking!
A. These herbaceous hibiscus are very prone to wind damage and must be planted in a sheltered position. They do better when four large stakes are driven into the ground about 45 cm (18 in) apart around the base of the plant and then strong wire netting wrapped around the four stakes holding the canes in an upright position. It is important to do this just as the shoots begin appearing in the spring, otherwise damage will be done to the plant.

Q. Are there any Australian native hibiscus?
A. Yes, there are over thirty‑five different species of hibiscus indigenous to Australia, with Hibiscus splendens possibly the most spectacular. The so‑called blue hibiscus of Western Australia has since been reclassified and is no longer recognised as a true hibiscus but as Alogyne huegelii. The blooms on some of these plants last only for a few hours.

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