Answers to some September garden issues

Published 12:00 am Friday, September 8, 2017

Generally, early September is a slow month for consumer gardening questions, but when I’m out and about I still receive a variety of horticultural and other plant-related questions.

Below are a few inquiries from the public about various issues posed to me that may be of interest.

Question: What is the vine blooming now that has some pretty white flowers? I see these blooms all around the county. I have never seen it before but it seems to be almost everywhere.

Answer: The vine in question is Sweet Autumn clematis or Clematis paniculata. It is an endogenous vine related to the cultivated clematis that is more familiar that blooms in the early spring. It’s a great addition to late summer landscapes, providing a spark of color to fading bedding plants. Cultivated varieties of this species are available that are more compact and somewhat less aggressive than the native vine. This early fall bloomer needs at least four hours of sunlight for maximum blooms. After bloom, the seed can be harvested to increase late summer color. Go to for more detailed information about fall blooming clematis.

Question: My trees and shrubs have grown a bit over the past few summer months.  Is it OK if I prune them now?

Answer: Yes, light, judicious pruning can occur all during the year. Avoid pruning spring flowering shrubs such as azaleas and rhododendron. If you prune them now you will eliminate many of your flowers. Prune those shrubs in the spring, after bloom. Prune the following shrubs back hard: holly, red tips or boxwood in the early spring to avoid winter damage. Maples should be pruned now while they have leaves to avoid excessive bleeding. Excessive bleeding is very common when pruning maples in the spring.

Question: I have yellow jackets in my lawn and I got stung last week while mowing. What can I do to get rid of these pests?

Answer: Insects are still active in the heat of the day even with the change in temperatures. Yellow jackets are particularly aggressive in the fall, especially when their food source is diminishing. The entrance to the underground nest is a single hole or cavity about the size of a quarter.  The best time to treat an underground nest of yellow jackets is late evening or early morning when the yellow jackets are quiet in the nest. Wasp and hornet sprays capable of delivering a straight stream of insecticides work best in destroying the insects’ nest. Point the steady stream to the entrance hole and empty an entire canister of the insecticide into the entrance hole. Sprays that contain ether are most effective with a quick response.

Cover the hole immediately to encapsulate the vapor, insuring a complete kill. Yellow jackets should be dead within 24 hours after an application of the aerosol insecticide.

More detailed information about yellow jackets can be found at

Darrell Blackwelder is the retired County Extension director with horticulture responsibilities with the North Carolina Cooperative Extension Service in Rowan County.