“Ask the Plant and Pest Professor” is compiled from phone and email questions asked the Home and Garden Information Center (HGIC), part of University of Maryland Extension, an educational outreach of the University of Maryland.
Question #1: I have 3 hanging baskets that are filled with purple petunias. The leaves are starting to turn slightly yellow and they aren’t blooming as well. They are in full sun and I water them every 2-3 days. Can you help?
Answer #1: It is not unusual for hanging baskets to take a break from blooming mid-summer. Petunias can even tend to get leggy. The yellow leaves suggest that perhaps this is a good time to apply a balanced liquid fertilizer labeled for flowers or houseplants. This would also be a good time to prune them back. Prune the stems back to about half their length. You can cut back to within a few inches of the base if needed, but do not remove all their leaves. Then water well to prompt new growth and flowers. This mid-summer overhaul should keep them blooming until the fall.
Question #2: This summer I had to put up a Japanese beetle trap near our Linden tree. The beetles were all over it. Their activity has slowed down so is it safe for me to take the trap down?
Answer #2: We do not recommend the use of Japanese beetle traps. Placing a trap near a plant that the beetles are attacking can actually draw more to the area and cause more damage. The pheromone used to attract the beetles to the trap is very efficient and can draw Japanese beetles from a large area. If you still insist on using them place them on your property as far away as possible from the plants you are trying to protect but also be respectful of your neighbor’s plants. Japanese beetles fly for about 4-6 weeks and plants do tend to recover from their damage.
Question #3: I have a grass-like weed that is rapidly spreading through my lawn. It first appeared about 3 years ago. It dies out every winter but comes back more intensely each spring. It started on the sunny edge of the woods. Please help me to identify it and any suggestions you may have for eradicating it will be greatly appreciated.
Answer #3: The weed sounds like Microstegium vimineum or Japanese stiltgrass. It is native of Asia, first appearing in the U.S. in 1919 and is now spreading rapidly throughout the eastern U.S. This is a very difficult plant to control and is highly invasive. It is an annual grass and has a lifecycle similar to crabgrass. Japanese stiltgrass has a fibrous root system, stems which are erect or reclining and roots at stem nodes. You can help prevent the spread of stiltgrass by mowing before it goes to seed in late summer. Small areas can be handpulled, although you need to be careful about disturbing the soil. Disturbed soil is an open invitation for additional weed seeds to germinate. In wooded areas use a non-selective systemic herbicide for control. In lawn areas apply a pre-emergent herbicide used for crabgrass control in early spring.
To ask a home gardening or pest control question or for other help, go to https://extension.umd.edu/hgic Or phone HGIC at 1-800-342-2507, Monday through Friday, 8 a.m. to 1 p.m. Follow us on Facebook and Twitter.
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