Garden Tips for August

(with excerpts from UMass Extension "Garden Clippings" & UConn Extension Center)


This summer many tomato plants are being hit by late blight - a devastating disease that can quickly kill tomato as well as potato plants. Late blight spreads very rapidly by wind-blown spores. Symptoms to look out for include large, irregularly shaped, dark spots on leaves and stems. Preventative applications of chemical fungicides labeled for late blight (Serenade for organic gardens, or Daconil for others) are generally most effective. Once plants are infected, there are no products that home gardeners can use to stop the spread of this disease. Infected plants need to be removed from the garden and discarded in plastic bags in your garbage. For pictures of what to look for, see

Be on the lookout for vegetable pests. Hornworms are large at this time and can strip tomato branches overnight. You can pick them off by hand or use B.t. (Bacillus thuringiensis) to kill them and prevent their return. Also watch for Mexican bean and Colorado potato beetles (which can be handpicked or exterminated with B.t.). Sevin is also very effective.

Apply a water-soluble fertilizer to late-season crops such as fall cabbage, Brussels sprouts, carrots, and leafy greens.

Cucumbers like lots of moisture and taste best when they grow rapidly. So give them a couple more doses of fertilizer (such as Gardentone, monthly; or a liquid fertilizer every two weeks) and continue to water until frost ends their season.

Begin harvesting onions, garlic, and shallots when their leaves are about 50% browned. Let the bulbs dry in the sun for a day or two, then store the bulbs for another week or two in a dry, airy location for proper curing.

Plant empty spots in the vegetable garden with crops that mature in less than 60 days or that can be mulched and harvested later in the fall. You can get a quick crop of leaf lettuce if you seed it now. You can also plant beets or turnips for November harvesting. We will have seedlings of fall crops available during August.

Trees & Shrubs

Rake up the fallen leaves of crabapple, hawthorns, apples, and pears. It is likely the leaves have fallen because they are infected with apple scab disease. The disease will overwinter on fallen leaves. Bury the leaves or bag them and put them in your trash.


For the rest of the summer, mow high (2 1/2") and often. Mowing too short during hot weather may be harmful to turf grass. Keep mower blades sharpened for a good, clean cut.

The last week of August and the month of September are the best times to start a lawn. Soil is much warmer then than in spring and grass seed with sprout faster and more evenly. Grass planted in late summer has twice as much time to establish itself before encountering the hot, dry summer of midsummer. Also, there is less competition from weeds, especially crabgrass, in fall.