Hibiscus, Star Jasmine, and Roses Same Damage

Q. This is a picture of my hibiscus leaf but my star jasmine and rose leaves have the same damage. Also, my hibiscus buds are falling off. I don't see any creatures. What do you think?

Hibiscus leaf with damage

 

A. When thinking about damage to leaves, the possibilities can be mind-boggling and confusing. The fact you tell me this same type of problem exists on the leaves of other plants usually means it is not a plant disease. If that is true, we can narrow down solutions to the problem better.

            Sun damage? When I first saw the damage to this leaf my first thought was “sun damage”. If this is an older leaf, then it could be damage caused weeks or months ago. If this damage is on newer leaves, then it is more recent damage and could still be going on.

            I am guessing this is damage to older leaves. I am guessing the damage occurred one or two weeks to a month ago, or perhaps even longer. The most important question is whether the newest leaves are showing this damage or not. If they are not, then the problem is gone and we are talking historically.

            If the problem is persisting on new leaves, then the problem still exists. Sticking my neck out somewhat, I think this may be an old watering problem during the very high temperatures of summer. If the younger leaves are not showing the same problems, then the plants were not getting enough water during the heat, but now are, since it's cooler and the need for water is less.

            If you have not done so, applying a 2 to 4-inch layer of woodchips to the surface of the soil helps during times of extreme heat and preventing this from happening.

            The issue of flower bud drop on hibiscus is usually water or temperature related; the soil is too dry or the air temperatures are too high. Woodchip surface mulch helps but make sure the plant is getting enough gallons of water each time it is watered. Growing it in bright, indirect light rather than full sunlight also helps.

            This plant may require adding another drip emitter. When temperatures begin cooling, you should start seeing flowers and less bud drop.