May 2, 2012
May can be one of the most diverse months for those who garden. Last May was damp and cold almost the entire month. Some years, it will warm up in early May and stay warm all month. Some years the month is dry, other years the days always appear to be rainy days. On average, you can expect the last average frost day to be around May 10th. You can get a frost as late as Memorial Day. Generally speaking, by the end of the month it is safe to plant everything in the garden. By the end of the month, we are officially into the “ Let’s plant everything” gardening season.
People have been asking this past week if it is safe to plant anything in the garden. I think that they feel that any cold temperatures will hurt all plants. Trees and shrubs are very cold tolerant. You can plant them from late March until early November. Perennials can be planted starting in April. There are vegetable plants that are cold tolerant. These would include lettuce, spinach, peas, broccoli, cabbage, Brussels sprouts, and cabbage. Cauliflower, kale, beets, radish, carrots, onions and potatoes. I may have forgotten a few but I deliberately left out tomatoes, peppers, squash, cucumbers, eggplant and basil. These are all plants that have their origins in more tropical climates. If you plant these plants before the last average frost date, you run a big risk of losing them to a frost. Yes, some years you can get away with planting these plants in late April or early May. But the odds are that if you plant early, you will lose the plants. It is best to be a bit conservative on planting your vegetable garden.
The question also comes up about planting annual flowers. People want to plant the impatiens as soon as possible. There are so many tender annual flowers that I can’t list them all here. You must realize that most annual flowers will be killed by a frost. With a last average frost date of May 10th, you are better off waiting until later in the month to plant most annual flowers. There are some annual flowers that will tolerate cold temperatures. Again the list would be too long to be included here. At the store, we try to bring in only the annual flowers that we think it will be safe to plant at any particular time during May.
The warm weather in March has made many shrubs flower early in the season. As the spring flowering trees and shrubs have finished their blooming time, you should give the plants some fertilizer. This will help the plants to put out new growth and to help them to set their flower buds for 2013.
Quite a few of you have noticed damage to the new leaves of your trees. The culprit appears to be the caterpillar of the winter moth. This caterpillar can do a lot of damage in a short period of time. An effective control for this stage of the caterpillar is an application of a product called Bt. This is a bacterium that kills caterpillars, yet won’t harm other beneficial insects. It is mixed with water and sprayed onto the leaves of the plant. The caterpillar will still consume a bit of the leaf, but very quickly it will stop eating and die within a few days. There are other products you can use, but this is probably the most effective spray.
Well, that’s all for this week. I’ll talk to you again next week.