Today the forecast is for summer-like weather, sunny and in the 80’s. A few weeks ago we had below-average temperatures and overnight lows in the teens. That’s spring weather in New England, swinging from winter cold to summer heat.
The average last frost date in our area is May 10 to 15, which means that there is a 50 percent chance of the last frost before this date and 50 percent afterwards. Frost can kill tender plants like tomatoes, peppers, sweet potatoes and basil. Since I am eager to begin harvesting tomatoes and all the other summer crops, I want to plant them out in the garden as early as possible. To protect tender transplants from temperature swings that head down near 32, and to make their growing season as long as possible, we use season extenders to protect the plants in case the weather turns cold again.
A visit to the gardening store or garden catalog will show you lots of season extenders, of which we use three.
1) To protect seedlings before transplanting as they harden off, we place trays of seedlings within the sheltering confines of our low hoop houses. Since these trap heat from the sun using the “greenhouse effect,” we need to stay alert and open these up in warm, sunny periods, lest we bake the plants to death. Should a cool night be forecast, we can close the hoop house up and the plants will stay toasty until the weather warms again.
2) Milk jug cloches are one of my favorite methods for protecting seedlings once we have transplanted them into the garden. It’s a great way to re-use all those milk jugs we go through. I use a utility knife to cut off the bottoms from plastic gallon jugs and pop one over each seedling. I leave the cap off so heat doesn’t build up too much inside the little microclimate. Milk jugs also keep the moisture in and protect the seedlings from the buffeting of spring breezes. We are using over 50 of these now on mid-season crops like leeks, lettuce, kale and parsley.
3) Floating row covers are lightweight non-woven fabrics covering rows or beds of crops. They protect plants from light frosts, help the soil retain moisture, and shelter seedlings from spring winds. Row covers also can protect plants from damage by insects like the flea beetles, which are already nibbling on some of our unprotected turnip sprouts.
Another form of season-extending is preheating the soil to reach optimum temperatures for heat-loving plants like tomatoes, peppers and sweet potatoes. We use black plastic (which absorbs heat from the sun) over beds where we are planning to put these tropical plants. It helps raise the soil temperature from mud-season April cold to July-like heat by the time we transplant our seedlings in late May or early June.
We gardeners are not in charge of the weather, and part of the adventure of growing vegetables is dealing with the many moods of Mother Nature. But as we learn techniques that can help buffer our garden plants from the vicissitudes of temperature and moisture, we increase chances of bountiful harvests — one of the rewards of the good life.