Why do buds drop off my hibiscus?
As past president of the Australian Hibiscus and the International Hibiscus Society, there’s no one better to teach about all things hibiscus plants than 87-year-old Over60 community member, Jim Prudie.
“This is my answer to the question which is put to me by people when I gave talks and at displays ‘Why do the buds drop off my hibiscus?’.
There are many causes for this problem, and it occurs when the plants are under some type of stress, like too much water, or not enough water, especially in hot weather.
Make sure that you keep the water up to your plants regularly, and you have to be very careful in the heat that you supply enough moisture to the soil for the plants to be able to draw up enough moisture from the ground, otherwise they will drop their buds. Never allow the soil to dry out.
Over watering can also cause the buds to drop, by causing the essential nutrients to be leached from the soil, thus causing a lack of nourishment to the buds, and they fall. This can happen when we get a lot of rain and the ground is saturated.
Excessive amounts of fertiliser can also trigger bud drop, especially if you use large amounts of Nitrogen, as this will trigger a burst of new growth, and all the energy will go the new leaves and the buds will not get enough of the nutrients, and bud drop will follow.
Changeable weather patterns will also cause bud drop, especially if there is a big difference in the day and night temperatures. Rainy weather after a dry spell will often start the buds falling, as the rain acts the same way as too much nitrogen and causes a burst of new growth, to the detriment of the buds, for a little while.
Insects are a big cause of bud drop, especially the Harlequin Bug and the
Harlequin Beetle, as they suck the juice from the junction where the bud joins the stem, and this causes the bud to fall.
I have seen buds fall after people have sprayed with insecticides, especially if they use too strong a mixture.
Mulching the garden beds will help with the moisture problem in the hot weather, as it stops the moisture from being dried up by the sun, and the soil stays nice and moist and cool and the plants are not so stressed. This will be most important if our present problem of no rain.
Some varieties have this tendency to drop their buds more than other plants, and hybridisers should take this into consideration when they are choosing their
parents for their hybridising. Doubles in hot weather are known for dropping their buds, as they take so long to open, and they can be affected by all of the above symptoms, while they are trying to develop.
There can be a combination of all of these symptoms which will cause your problem with bud drop, so you have to look at fixing all the problems, if you are partly going to stop the bud drop, although in the hot weather which we get, I am afraid it is a bit of a losing battle, and it is best not to expect too many flowers in the hot weather, and be content to wait for the cooler weather to come.
I have it said to me that people think that some insect nicks the buds off, which can happen if you get an attack of the Harlequin bugs and beetles, but it can be a natural thing for the plants to do this whenever the plant is under some type of stress, and it is usually during the summer heat, and soon as the weather cools down the buds will stay on, and you will start to get more flowers."
Related link: Jim Prudie on how to prune a hibiscus plant