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

Repelling slugs from perennials, keeping strawberry plants in bounds, and watching for powdery mildew disease are some of the gardening tips for this month.

Dark leathery spots on the blossom end of tomatoes is likely to be a condition called "blossom end rot" that's caused by uneven watering. Mulch will help moderate the fluctuating moisture levels that nature provides, and it's not too late to spread some around your plants.

Coffee grounds, diatomaceous earth, and even sharp gravel can deter slugs and snails. Spread any of these materials in a ring around individual plants. Wrap pots with copper tape to keep slugs from crawling up. Inspect foliage and squish or pick off any insects that have already passed the barriers.

Strawberry plants are in very active growth these days, and new runners will proliferate. Remove runners to keep plants spaced according to the method you're using so plants will put their energy into producing future fruit instead of new runners. Left alone, a bed will turn into a mass of foliage and few berries.

At the first sign of powdery mildew on phlox, bee balm, and other susceptible
plants, treat with a fungicide.  Research has shown horticultural oil and products related to baking soda, applied every two weeks, to be some of the best controls.  Read and follow all label directions before use, even on seemingly “safe” products.

Allow lawn grass to grow higher in midsummer to reduce heat stress. Set your mower height to 2-1/2 to 3 inches. Less stress on lawns results in fewer weeds.

Birds love blueberries as much as we do, so protect the fruit with netting. Rather than draping the netting over the bush -- birds will still be able to reach the berries -- use stakes to suspend the netting over the shrub. Secure the netting to the ground to prevent birds from sneaking in. Get your cover in place before the berries turn ripe.

Even if you can't eat them all right now, take advantage of the abundance of fresh fruits and berries. Freezer jams are surprisingly easy to make, and even regular "canned" jam is pretty straightforward and makes a great gift. At the very least, freeze some berries for later use; simply spread them out on a cookie sheet and place them in the freezer; once they've frozen, pour them into freezer bags and seal.

Other gardening tips for this month include picking blueberries at a local farm,  stop pruning trees and shrubs, and visiting specialty perennial nurseries.  You can find an updated listing of Vermont perennial and herb display gardens online (

Return to Perry's Perennial Pages, Articles