University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article


Charlie Nardozzi, Senior Horticulturist
National Gardening Association, and
Dr. Leonard Perry, Extension Professor
University of Vermont

Harvesting onions, collecting seeds, and keeping newly planted trees and shrubs watered are some of the gardening tips for this month.

Begin harvesting onions when about half to three quarters of the leaves have died back. Then gently dig or pull the onions and store them in a dry, shady place with good ventilation, such as an outdoor shed or barn, for 10 days to 2 weeks. After the onions have cured, put them in slatted crates or mesh bags and store them indoors in a cellar with low humidity and temperatures between 33 and 45 degrees F.

Collect seeds from early-maturing plants, such as columbines and lupines, and either replant immediately or place in jars for storage. You can also allow the plants to drop their seeds naturally, then move the transplants next spring. When sweet peas fizzle out, allow them to set seedpods and harvest the seeds for planting next year.

It's not too late to sow lettuce, beets, carrots, radishes, and other short-season crops for a late-summer harvest. Shade lettuce, if possible, during late afternoon to keep young plants cooler, or grow them next to larger plants that provide some shade. You'll need to water more often on these hot days than you did in spring and early summer. Mulch between rows to preserve moisture and block weed growth.

Don't rely on nature to provide enough water for trees and shrubs that you've planted this spring or summer. The roots will continue to grow into the fall until the soil is about 45 degrees, and deep watering once a week will encourage these roots to go deeper.

Keep watch for a few new pests which may arrive this time of year.  The tomato hornworm is a three-inch long, green or brown caterpillar with eight curved stripes and a characteristic "horn" sticking up from its backside. Hand pick and drown in soapy water or snip in half. Control the smaller worms with B.t. (Bacillus thuringiensis), a biological control.

The corn earworm migrates on storm fronts from the South. Soon after arrival, the adult moths lay eggs on fresh corn silks, then the larvae feed in the tips of the ears.  To prevent earworm damage, apply three to five drops of vegetable oil directly to silk channels at the tip of the ear.  The best time to apply oil is four days after the silk starts to grow, when the tips of the silk are just starting to wilt and turn brown.

Other gardening tips for this month include lining up a plant sitter for your vacation, entering flowers and produce in a local fair, and dividing bearded iris.  Visit the National Gardening Associationís web site ( for more information on gardening and regional reports.

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