Here are this week’s gardening questions and answers, provided by Parker County Master Gardeners. To submit a question, send it to firstname.lastname@example.org. For more information about Parker County Master Gardeners, or to become a member, call 817-598-6096 or visit www.pcmg-texas.org.
When should I prune my garden mums?
Garden mums are a perennial that will bloom twice each year if they are not pruned. However, the stems will be long and floppy and the flowers will be small. Timely pruning will greatly improve the appearance and the bloom of the plant.
In mid spring, when mums fill out with leaves and flower buds, prune the plant back to about 8 inches tall. Around the first of July, lightly prune them again by pinching off the soft green stem tips.
Be sure to take off only the pliable part of the stem. Then, let the mums grow. They’ll develop flower buds for brilliant blooms in late autumn. In late winter, cut dead stems to the ground. New leaves will sprout in the spring from the underground roots.
Genista caterpillars are eating the leaves on my Texas mountain laurel. What can I do to get rid of them?
You can remove the caterpillars with a high-pressure water spray. An insecticidal soap can be effective on small, young larvae without introducing harsh chemicals to your landscape. Insecticides such as BT (Bacillus thuringiensis), spinosad or pyrethrins can be used on large infestations.
These are recommendations from the Parker County Master Gardener handbook, the real dirt and from our IPM (Integrated Pest Management) guidelines. This pest is a problem in a relatively small market, and it may be difficult to find them listed on the label; so look for the ingredients we have suggested.
All pesticides should be stored in their original, labeled containers and kept out of the reach of children. Never dispose of pesticides in a storm drain or any other drain.
Can I use lava rocks as mulch for crape myrtles?
The purpose of mulch is to retain moisture, insulate the soil from extreme temperatures and reduce competition for soil nutrients by discouraging grass and weeds. Mulch also adds nutrients to the soil as it breaks down over time.
While lava rocks may be attractive in the landscape, they will not retain moisture and will actually increase the temperature of the soil during warm months. In addition, lava rocks are quite difficult to work around in the landscape and may cause unexpected problems.