Garden Jobs

Things to do this week:

* Back off on bougainvillea. For the best blooms and brightest colors, water bougainvillea less often and do not fertilize. Established plants in the ground need virtually none while they are in bloom. Only plants that are still young and have not filled their spot in the garden need fertilizer or regular water. So do plants confined in pots.

* Prune hibiscus, princess flower. Prune as much as one-third of the growth from princess flowers (Tibouchina) or hibiscus, and they will bounce right back with more flowers and denser growth. On both plants, flowers form only on vigorous new growth. Pruning is best done now during warm weather.

Where are whiteflies? Be on the lookout for giant whiteflies and blast them off with plain water when first seen. A few gardeners are convinced that a half- to 1-inch mulch of worm castings around the base of plants will drive the insects away, but it’s hard to determine effectiveness so far this year because conditions have not favored the whitefly, and natural predators are making a dent. Poison sprays are still not recommended, though some hibiscus growers find a new spray containing a chemical similar to nicotine, named imidacloprid (in products by Bayer), to be effective with supposedly low toxicity to mammals. It is highly toxic to fish and bees, however.