University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article

By Dr. Leonard Perry, Extension Professor

Dr. Vern Grubinger, Extension Associate Professor
University of Vermont


With our short growing season in Vermont, we have a limited amount of time in which to do a lot of gardening. But the good news is that just about everything that needs doing in the garden can be done in June.

But because the gardening season is so short, we need to keep the garden growing as vigorously as possible. This means keeping it well weeded and well watered.

Mulching also helps keep weeds down and much-needed moisture in the soil. You can use organic mulches such as straw, weed-free hay, grass clippings, shredded leaves, or bark, or synthetics such as black plastic or ground cover mats.

Wait until the soil has warmed up--in most years that's early June--before applying most of these mulches because they insulate the soil. However, as plastics help warm the soil, they should be applied earlier.

Be sure to remove weeds and thoroughly water the soil if necessary before mulching. Don't use plastic and synthetic materials around perennials as it keeps them from their natural spreading.

Thin carrots, beets, and flowers when still small to provide good air circulation between plants. This helps avoid competition and prevents or reduces incidence of foliar diseases. Be vigilant about pest control. 'Scout' young crops for the arrival of pests by closely examining plants every few days.

Combat early season pests like cutworms with cardboard collars placed around tender transplants. A thick layer of straw mulch around potatoes can deter Colorado potato beetles. Put a floating row cover such as "Remay" over transplants to keep cucumber beetles off cucumbers and squash.

On cauliflower, broccoli, and other cole crops, the imported cabbage worm is another garden pest common in June. At the very first sign of small holes, inspect the leaves of your broccoli, cauliflower, cabbage, Brussels sprouts, kale, and mustard plants carefully for tiny caterpillars, then spray all the leaf surfaces with Bacillus Thuringiensis (B.T.), a biological insecticide available at all garden centers.

A different kind of B.T. can be used to control the smallest larvae of Colorado potato beetles. Keep an eye out for the tiny orange "slugs" and nail them early with this very safe, biological insecticide.

Fertilize roses this month using a cup of 5-10-5 or similar organic fertilizer per plant. Mulch with three to four inches of bark mulch around the base of each plant. Water well and often.

Shrubs and perennial plants also should be fertilized now. An application of 10 to 30 pounds of 10-10-10, or similar all-purpose blend, per 1,000 square feet of border can be used as a general guide. Or even better, add fertilizer according to your soil test results. Complete organic fertilizers often are sufficient, and many are slow release so you don't need to reapply them later in the season.

Don't be alarmed if your fruit trees seem to be dropping a lot of their fruit. This is nature's way of thinning out the crop although in some cases it is the work of plum curculio, which is active laying eggs in developing fruit in late May and early June, often leaving a moon-shaped scar.

If you don't have this pest, or controlled it with timely insecticide application, further thinning may be needed. As a rule, thin clusters of apples to one fruit each, so remaining fruit is spaced about six to eight inches apart on the branch. Thin pears to about five inches apart, plums to six inches.

June is the time to plant tuberous begonias, dahlias, and gladioli. If you have shady spots to fill, try hostas with their large, colorful leaves. Siberian irises, which don't mind "wet feet," are suitable for wet areas.

Mow your lawn frequently, and sharpen your mower blade often to help prevent diseases later in the season. Allowing your grass to grow to five or more inches between mowings only increases the risk of shock to the grass when it is cut and takes it longer to recover, especially during dry periods.

Cut the grass high, not short, to help it withstand drought and capture sunlight for energy and best growth. If you decide to apply a lawn fertilizer, keep in mind that those containing weed killers should not be used near trees. When watering, water well and deeply (equivalent to one inch of rain) or not at all.

Remember your Dad this Father's Day (June 17) with a living tribute--a tree or shrub planted in his honor. Work with the experts at your local nursery to determine what species are most suitable for the site you have selected.

No room for a tree? Then why not give Dad a gift certificate for his favorite garden center, or offer to help him plant his garden.

Other activities for June: go strawberry picking, buy a rain gauge, sow seeds for foxglove and other biennials for bloom next year.

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