University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article

Charlie Nardozzi, Horticulturist and
Leonard Perry, UVM Extension Horticulturist

Pinching back annuals and late-blooming perennials, tending to strawberries regularly, and edging beds are some of the gardening activities for this month.       
It's a good idea to “pinch” or prune back many annual flowers, such as coleus, petunias, snapdragons, zinnias, impatiens, and salvia, early in the season and again whenever they start getting leggy. Pinching encourages the side buds to grow so you'll get more flowers. Pinch just above a node on the stem where leaves attach. The lower you pinch on the plant, the bushier it will become, but a low pinch often will reduce the ultimate height of the plant. 
Pinch back late-season flowering perennials, such as phlox, asters, Helen’s flower, Joe Pye, and Russian sage, now for shorter and fuller plants. Extend the bloom time by pinching half of them, because the pinched ones will bloom a few weeks later than the unpinched ones. Remove the top one-third of shoots.
Once early summer perennials, such as peonies and foxgloves, have finished blooming, take the time to clip off the spent flowers to spare the plant the energy it would spend on forming seeds.  Don’t clip old flowers if you plan to save the seed and do some propagating of your own, or leave the seeds for birds. For seed collecting, leave some seedheads until they turn dry and then harvest before the wind and the birds get to them.  For some perennials that self-sow readily such as mallows, make a note to cut off flowers when done unless you want many seedlings.
If you don't have an edging material around the borders of your garden beds, use a flat spade to shave off clumps of sod to delineate the edges. You'll probably need to do this a couple of times, but if you don't you'll be fighting encroaching grass all summer.
To allow good drainage in your container plantings, raise the pots off the ground or deck so water can seep out the drainage holes. This also will reduce the staining that can occur when pots sit directly on wooden steps or a deck. You can purchase pot feet or plant caddies from garden supply stores, or make your own pot feet using flat stones of similar size, rubber bumpers from the hardware store, or even old checkers from the game you never play anymore. 
Harvest strawberries frequently, and remove any that show signs of grey mold or rot diseases. Not only are these berries inedible, they quickly spread disease to other ripening fruits. Mulch under plants with straw to reduce contact with the ground where the disease spores reside.
Growing grapes?  Then you should remove any flower clusters the first two years after planting.  In the third, and subsequent years, thin grape clusters when grapes are about 1/8-inch wide, leaving only one or two bunches of grapes per new shoot.
If you’re growing berries, cherries, or grapes, you should get familiar with their latest pest—the spotted wing drosophila—a vinegar fly, somewhat like a fruit fly.  The fly lays eggs in ripening fruit, which hatch into small worms or larvae in the ripe fruit.  You can place large cups with an inch of vinegar cider vinegar among your berries to trap flies.  If just a few plants or rows of berries, cover them with a fine netting such as row cover fabric as the fruit begin to ripen to hopefully keep the flies away.  There are a couple of organic sprays you might use as well—check with your local full-service garden store for available and appropriate products.
Make plans to visit local perennial nurseries this summer (

(Charlie Nardozzi is a nationally known horticulturist, author, gardening consultant, and garden coach; 

Return to Perry's Perennial Pages, Articles uvmext logo