We have 2 large (about 8 ft tall) hibiscus bushes in our backyard here in Solana Beach, CA, but I'm concerned because several of the leaves keep turning yellow. There is a drip sprinkler to water the plants for about 4 minutes each day. I sprayed for whitefly a couple weeks ago because I noticed some small partially transparent spiders, and last season we had extensive whitefly infestations! Also, I placed snail pellets since about a month ago we noticed snails getting up into the foliage and red blossoms! In January I trimmed both bushes back about 1/5 of their size because they were very overgrown last summer and fall. New small green leaves developing on the stem ends don't seem to be maturing properly into larger healthy leaves, so I'm concerned that some infestation is causing the yellowing of leaves and stunting of new growth! Any remedy to recommend?
Certified GKH Gardening Expert
Yellow leaves signal stress, most likely from the pests. This article will help you: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/answers-to-what-causes-hibiscus-leaves-turning-yellow.htm For the pests, you can treat the hibiscus with neem oil, which is effective on many types of insect pests. This article has more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm For additional help with the snails, try this article: https://www.gardeningknowhow.com/plant-problems/pests/organic-snail-control-how-to-control-garden-snails.htm And finally, it is normally better to wait for spring to prune these plants. This article will help: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/tips-for-pruning-hibiscus-plants-when-to-prune-hibiscus.htm