The fourth week of August is time to reset for the coming fall season in the garden. Garden centers and nurseries will soon be stocking autumn bloomers like chrysanthemums, winter pansies and ornamental cabbage. The vegetable garden needs frequent water and harvest this month in order to enjoy and preserve the tomatoes, corn, beans and squash at the peak of harvest. Harvest often and donate any extra produce to your local food bank.
Q. How can I prevent late blight on my tomato plants? Last year I lost most of my crop late in the season when the foliage started to turn black and the whole plant rotted, leaving me with only a few tomatoes to harvest. A Master Gardener told me the disease that killed my tomato plants was late blight.
A. Late blight is the heartbreak of tomato growers in Western Washington as this fungus hides in the soil to infect tomato plants late in the season at the peak of ripeness. The key to escaping this attack of fungus among us is to know some facts. The blight needs three things: tomato plants, the fungal spores and damp foliage. You can control just one: keep the leaves of your tomato plants dry and the blight will not be able to grow. Some gardeners erect elaborate frames covered with clear plastic over their plants but the easy way is to grow your tomato plants under the eaves of the south or west side of the house where they will enjoy the hot afternoon sun but be protected from the rain. You can also try using clear plastic umbrellas over your plants to keep the foliage dry.
At the first sign of leaf blight (look for leaves and stems that turn black), harvest the tomatoes and then uproot and send the infected vines out with the garbage. Do not compost infected foliage and rotate your tomato crop if you grow plants in the ground.
Q. My clematis vine has overtaken the small Japanese maple tree that is was using as a support. You were the one that suggested we use living trees and shrubs as supports for clematis instead of a lattice. Is it OK if I prune the clematis now so it won’t overpower the tree?
A. Drop those shears. Late summer is not the time to prune clematis or roses. Pruning stimulates growth and you want these plants to slip into dormancy before winter and not be stimulated into producing tender new growth. An exception to this general rule of green thumb is if the clematis vine is so heavy it threatens to break a limb or hides the foliage of the maple. If this is the case, prune back the vine by at least half and hope for a mild winter.
I admit, I do recommend growing clematis through small trees and shrubs. To keep any overly enthusiastic clematis under control, prune after blooming if the clematis flowers in spring (clematis armandi and montana) and prune in early spring if the clematis flowers in the summer (clematis jackamani, Nelly Moser and others). Just grab all the clematis stems in your hand about one foot from the ground. Cut and pull the old vines from the supporting plant. The new growth will flower later in the season but with a more tidy look.
Q. We have a first crop of homegrown corn growing in our garden and are excited to harvest the crop. My question is how to know when the sweet corn is at the peak of sweet ripeness. We are thinking of having a harvest party to celebrate our corn.
P.P., Maple Valley
A. A harvest party is a wonderful idea and the trick to telling when corn is most sweet is to puncture a kernel with your fingernail while it is still on the stalk. Just fold back the husk to get to the kernels. If the liquid that comes out is thin and watery, the corn needs more time. If the puncture reveals a thick liquid it is overripe. What you want to find is a milky white liquid that leaks from the punctured kernel. This will indicate the peak of ripeness. Then get the water boiling, harvest the ears and immediately drop them into the boiling water. The sweetest corns on the cob are from ears that spend the shortest time from harvest to cooking.
Marianne Binetti has a degree in horticulture from Washington State University and is the author of “Easy Answers for Great Gardens” and several other books. For book requests or answers to gardening questions, write to her at: P.O. Box 872, Enumclaw, 98022. Send a self-addressed, stamped envelope for a personal reply.
For more gardening information, she can be reached at her Web site, www.binettigarden.com.
Copyright for this column owned by Marianne Binetti.