Blue Hibiscus (Alyogyne huegelii) Problems
Question from Anne:
You were so help several months when I had pruning problems with four passiflora vines that I have, so I thought I would contact you again with a little problem. I have a three-year old blue hibiscus in my backyard, and it grows beautifully for a couple of months, then its small branches start to turn brown and no new growth appears. It looked lovely a month ago, and now the growth that was new a week or two ago is wilting and dieing. I have a drip system around it, watered once a week running 55 minutes. It is in the sun in the morning (when there is sun!), but no sun in the afternoon due to a cinderblock wall blocking the western exposure. What could possibly be the trouble? Not enough sun?
Answer from Pat:
I am sorry to tell you that I think you have put your finger on the main source of trouble with your blue hibiscus (Alyogyne huegelii). It needs full sun and it’s only getting half a day of sun, if that. We have had overcast skies in coastal zones all summer this year. but even when skies are overcast if a plant is located in a spot where it would normally get full sun, the sun would shine through the clouds somewhat all day long. If a wall is in the way half the day this is not possible.
Irrigation might be another difficulty. I am aware that Sunset Western Garden Book says blue hibiscus needs little to moderate water, but in my opinion that only applies if the plant is growing in water-retentive soil. My own experience is that it grows and blooms much better when grown in well-drained soil that is consistently moist and dies or does badly if the root run dries out.
Most importantly it needs a hot spot or at least a warm sunny spot.
Another need of this plant is frequent pinching back to make it branch. The more you prune it the better it grows. People hesitate to prune it because the flowers grow on the tips. In order to prune it you have to sacrifice flowers. The best idea is to cut back the two longest stems on opposite sides of the plant one-third of their length, every two weeks throughout the growing season.
Finally, fertilize with a balanced organic fertilizer throughout the growing season. Seabird guano is one of the best and fastest acting organic fertilizers you can use and this makes for flowers too. Water the fertilizer into the ground. Drip systems might not give enough water out to accomplish this and so salts might be building up in the soil which could explain the brown leaves.
When leaves go brown on their tips this is leaf burn from wind or from burned or damaged roots, perhaps from salts or fertilizer burn. When whole leaves go brown and drop off this may mean lack of water or may result from a sudden cold spell. Wilting of new growth also can come from lack of moisture or it might result from mildew damage as a result of cool overcast weather. Treat mildew with Serenade™ which is a safe, organic fungicide. It works best, however as a preventative spray. Leaves also can drop off from changes in weather and soil moisture. Finally, branches sometimes die on blue hibiscus due to lack of robust all-over health, too much shade, and general decline. The best way to prevent this is by giving the plant everything it needs and keeping it growing rapidly which unfortunately you’re not able to do because your plant is not in full sun. Alyogyne are not long-lived except in the very best of circumstances.
Thank you so very much for your thorough analysis of the trouble with my blue hibiscus. I appreciate all your information, and I will attempt to try all your remedies. Of course, I will move the plant as a last resort as that in itself could kill the plant. When I see healthy ones, I anguish over why mine can’t look as beautiful, so when my plant looked so good for a few months, I thought “ah ha!–maybe it will be okay– but not so! I will report my results to you.
Transplanting a blue hibiscus is an iffy proposition at best, but if you attempt this, I would do it in fall when the winter rains could help the plant recover. The right time to plant or transplant tropicals, such as palms is spring or even summer, if the weather is mild, while they are actively growing, but this is not really a tropical plant, but a subtropical one. Make sure roots are moist, cut back the plant by two thirds, trench around the roots, then ball them in burlap and transfer to the new hole. Drench roots in humic acid and you might have a chance for success.
In the meanwhile you might try treating the ground around the roots of a plant with a product such as John and Bob’s Soil Activator. You would have plenty left over for other plants. If you didn’t already purchase seabird guano, seaweed and fish emulsion could be another choice of a helpful fertilizer to use as a soil drench. But all these products are expensive. Sometimes it’s better to admit failure and plant another one in a better spot. Regarding your wilting and dying branches if just one here or there on a specific side of a plant, this might mean something is harming the roots or could be a case of a borer inside the branch. When you cut off a damaged branch inspect at the base of the die-back for borer.
It is difficult when one falls in love with a plant and it’s growing in the wrong spot, because one is almost always doomed to failure, which can be a heart-rending experience.
It’s not always easy to be realistic about plants. Only a few cast iron types are foolproof.
I planted two hibiscus in the spring in huge pots with good potting soil. They grew rapidly and bloomed beautifully until about a month ago. Now the flowers (very few) are stunted, and the buds pale, and drop off at the slightest touch. I have kept them well watered in this Florida heat. Please advise. Thanks! Patricia
Most likely bud drop from hibiscus plants was caused by a sudden change of temperature, a cold snap followed by heat. If so, there is nothing one can do to stop it. If this is the cause I can only suggest that a regular fertilizing with azalea and camellia food could help keep the plants in good health so they will set more buds. That said, a lot more possible but less likely causes occur to me. Thus I will write them just in case they fit the circumstances.
Several pests can cause the buds to fall off hibiscus before flowers open, thrips being one of them. You mention that you have not seen pests, but you might try opening one of the fallen flowers and see if there are thrips (little thin black shapes) hidden inside. I have found ladybugs to be a good control for thrips even though the thrips are largely hidden, the larvae of lady bugs and green lacewings will kill the immature thrips. Organic soils help too as do nsecticidal soaps and summer oils. There are also some beneficial insects called minute pirate bugs (Orius tristicolor) available by mail order that are very effective at controlling thrips.
Here are some other ideas: Hibiscus plants generally don’t do well in pots. You mention “hibiscus” but fail to say what kind. Is it a tropical or Chinese hibiscus or a blue hibiscus? These plants are entirely different. Blue hibiscus (Alyogyne huegelii) is a Mediterranean plant from Australia. Keeping their roots very wet in a pot in high heat will cause root rot. This plant usually grows best in the ground in full sun and a warm spot but in well-drained soil and must not be overwatered. Additionally, sometimes people think that they are watering a lot when they add water daily but not enough for the water to run out the bottom of the pot. It is okay to water tropical plants often in hot weather because they come from wet climates but not with blue hibiscus which comes from a dryer climate and likes better to dry out between waterings. Also water must flow out the bottom of the pot every time to wash away salts and also must not be standing in a saucer or the roots will rot, and this applies to most plants.
Chinese hibiscus (Hibiscus rosa-sinensis) is a tropical but it often does badly in pots. Usually the leaves become small and stunted when they are grown in pots. This shows there just is not enough room for roots. The pot size needs increasing and also water and fertilizer. Falling leaves are typical when hibiscus are stressed. Pale and stunted flowers falling are a sign of stress also. Both these problems usually arise from a sudden change of temperature or a sudden loss of sunshine. Also if the plants grew well and bloomed for some time and then stopped, did you fail to feed? Hibiscus plants need fertilizer throughout warm weather which means throughout their growing season and especially when grown in pots because then they are dependent on you for food.
If possible I would get these plants into the ground where they can spread out their roots, fertilize them once reestablished and water well but not too well. Roots must not be in a swamp. The tops of the plants should be able to withstand the heat much better if the roots are kept cooler. Also, how are the night temperatures? Fancy varieties of tropical hibiscus need night temperatures of 60 degrees Fahrenheit or more in order to bloom. This is why a cold snap makes buds fall off thereafter. In some climates the days are hot but the nights are cold but I doubt that is the case in Florida.
Another point: when sun hits the side of a pot on a hot day it can fry the roots inside. If you have nowhere in the ground to plant it then try to place the pots so that the side of the pot is shaded from the hot sun.
I live in N. Scottsdale, AZ where the days can get up to 115 degrees and the nights, in the winter months, can get down to 20 degrees. I am at much higher elevations than Pheonix, where the blue hibiscus seems to do real well. Some months can also get windy here. I had planted a blue hibiscus last Fall with a drip line (watered twice a week for 1 1/2 hours at 1 gallon) and in full sun with amended soil. It didn’t look great from the get go–some leaves yellowed. Then a few months later it started to look good with green leaves, although it didn’t bloom. After our winter, with only a few days of frost, it dried out and died. I can’t get a straight answer from anybody as to what temps this plant can take and do I need to cover with frost cloth in the winters, as I would love to plant another plant. Our wild orange mallows do well and live through the winters. My husband thinks that it did get the right amount of water as it had looked good before late winter.
Blue hibiscus (Alyogyne huegelii) is adapted to growing in Sunset climate Zones13-17, 20-24; H1 and H2. You live in Scottsdale Arizona, most likely in Sunset Climate Zone 10 or 12, thus blue hibiscus cannot survive outdoors year-round in your climate. Though it is tempting to grow plants we particularly love whether or not they are well adapted to the climate where we live, one of the skills of good gardening is to choose plants that grow well where we live. Every climate in the world, even bare sandy deserts have at least a few wonderful plants adapted to that particular climate. My advice is to choose the most spectacular plants you can find that grow easily where you live and grow those.
Is it possible to propagate alyogyne huegelii from cuttings? Will they root in water?
Most blue hibiscus (Alyogyne huegelii) are grown from half-hardy cuttings, though it works just as well for home gardeners to grow them from soft-wood cuttings. To take soft-wood tip cuttings the best time is March. In March take 6 or 8 inch long bendy cuttings from tip growth. (Soft-wood cuttings break if you bend them.)
After clipping off a cutting three sets of double leaves, cut off the bottom two sets of leaves but leave the top pair in place. Fill a small pot with potting soil, dip the lowest joint in “Dip It”, a growth hormone. Then using a chop stick, make a hole in the potting soil in the pot, insert the cutting and press the soil firmly but gently down in the pot so the cutting is firmly anchored. Water thoroughly, cover with clear plastic and keep the cutting or cuttings in bright light but no full sun until well rooted. Water as needed. Then move into partial shade and pot on into larger sizes as required.