University of Vermont
Department of Plant and Soil Science

gmg logo   Summer News Articleline

CONTROLLING SLUGS AND OTHER JUNE GARDENING TIPS

Leonard Perry, UVM Horticulturist
and Charlie Nardozzi, Garden Consultant

Controlling slugs and mosquitoes naturally, raising containers for better drainage, and fertilizing warm-season vegetables are some of the gardening activities for this month.

With the summer weather upon us, slugs in some areas (particularly wet ones) may seem everywhere. They eat holes in the leaves of many vegetable, annual, and perennial plants.  One of their favorites is one of gardeners’ favorite perennials—hostas.  There are many chemical and non-chemical controls for slugs, including one that contains iron phosphate as the active ingredient. The slugs eat the pellets and die, yet the iron phosphate doesn't harm other wildlife or the environment (it may harm earthworms).  Avoid other toxic baits, as children or pets may eat them with serious consequences, perhaps death.

There are many other methods to trap slugs, such as under boards or in wet newspaper rolls in the garden.  The more famous trap is saucers of beer which attract them and in which they drown.  Some gardeners swear by coffee grounds, sharp gravel or egg shells sprinkled around plants, while others report mixed results at best. Yet the caffeine from a weak coffee spray often deters slug feeding on leaves. You can buy copper strips or products to place around choice plants, just for this purpose.  These supposedly repel slugs through creating an electrical charge as they cross. 

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 from garden supply stores, or make your own using flat stones of similar size, rubber bumpers from the hardware store, or even old checkers from the game you never play anymore. Anything that will elevate the pot a bit should work. Bricks work well for containers on the ground.

Examine your yard for areas with standing water, such as old tires or upturned garbage can lids, and dump them. Mosquitoes breed in these types of places, so by removing them you'll get a head start on controlling the pests.  The larvae that hatch from eggs need about 10 days to feed on organic matter in the still water.  Use "mosquito dunks" in ponds or rain barrels. These disks contain a specific strain of Bt (Bti, a natural bacterium) that controls the mosquito larvae.  Covering rain barrels with a fine screen may be all that’s need to keep mosquitoes from entering and laying eggs.

Sow new crops of beets, carrots, and summer lettuce to extend the harvest. You don't need much space, you can sow a border around other vegetables. If possible, choose a spot that's partially shaded by taller plants for sowing lettuce, so it will stay cooler.

Tomatoes, squash, and cucumbers can use some nutrients now, so scratch some granular fertilizer into the soil around plants or in a shallow trench alongside a row. Do this when the soil is already moist, and then water it in.

Where does one begin when choosing a hosta among the hundreds available?  You might start with the hosta of the year, named each year by the American Hosta Growers Association (www.hostagrowers.org).  For 2017, the winner is ‘Brother Stefan’--  medium sized (just under two feet high and three feet wide), with crinkled gold leaves and wide irregular green margins.  White blooms appear in early summer.

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

Return to Perry's Perennial Pages: Green Mountain Gardener Articles-- your reliable source of gardening information for over 50 years.