January "In The Grow" - Indiana Yard and Garden - Purdue Consumer Horticulture

January “In The Grow”

Q. This spring I got two hibiscus trees and discovered they had spider mites on them. I took them outside and fought them all summer. When I brought them inside, the mites were still there. One day, I sprayed with a spray that I was told to use. They lost all their leaves. Now they are starting to get new leaves. How do I keep the mites off them? How do I care for a hibiscus tree properly?
– L. Lemler

A. Generally, one application of miticide is inadequate to completely kill the spider mite population. It’s important to follow the label directions concerning reapplications because those recommendations are timed specifically for the pest. It’s likely that the spray you used knocks out the adult mites but leaves the eggs unharmed. If the directions said to reapply in 10 days, that second application would have killed the newly emerged mites.

While the plants are outdoors, you can knock the mites off with a strong stream of water. When it’s time to bring them inside, inspect them and treat as needed with insecticidal soap so they don’t infest the rest of your houseplants.

Hibiscus requires bright light, moderate water and fertilizer, and occasional drastic pruning to keep it within bounds of the average house. It can be cut back to within 6 inches of the base in early spring.

Q. We cannot find the sticky, yellow traps for white flies on houseplants. Please tell me a nationwide store chain or mail order catalog where we can purchase them.
– Craig and Laura Lenhart, Lawrenceburg, Ind.

A. The following companies carry yellow sticky traps: Gardens Alive, <www.gardensalive.com>, (812) 537-8650; and Gardener’s Supply Co., <www.gardeners.com>, (888) 833-1412.

Q. I have a six-year-old mock orange plant that doesn’t bloom. What do I do?
– Fern Catt, Decker, Ind.

A. There are many reasons why your mock orange or many other plants may fail to bloom. Some plants have a juvenile stage and must mature before blooming. Temperature plays a part with late spring cold snaps that damage flower buds or even excessively cold winter temperatures. Excessive nitrogen fertilizer promotes an overabundance of leafy growth at the expense of flower formation. A balanced fertilizer, such as 12-12-12 or 6-10-4, ensures that your plants receive nutrition in the correct amounts.

Mock oranges and many other blooming plants require a good dose of sun and will flower poorly, if at all, in the shade. Consider pruning overhanging branches or relocating the plant if it is not receiving at least a half day of sunshine. Finally, spring-blooming shrubs should not be pruned in winter or early spring since that process removes the flower buds.


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