Cool-weather plants, such as lettuce, cabbage, broccoli, and peas, are happiest when planted in the early spring and harvested before the heat of summer sets in. So does that mean you can’t have fresh lettuce during the summer months? Of course not! Simply continue to plant your cool season crops every two weeks throughout the summer months.
Extend the Harvest
You can harvest the cool-season crops started during the summer in the fall. The harvest of many of these crops can be extended into winter with the use of a simple cold frame. Some crops such as kale, Jerusalem artichokes and Brussels sprouts actually taste better after they have been through several light frosts.
The main problem with growing cool-weather plants once the heat of summer arrives is that they tend to bolt, or go to seed. When a plant bolts, it quickly sends up a tall flower stalk, and once that happens, the flavor of the crop declines.
Create the Right Environment
You can extend the season of your cool-weather crops in several ways. One is to grow these crops in a tunnel house. To create the right environment, install shade cloth along the length of the tunnel. Shade cloth is a synthetic fabric manufactured to let a certain percent of sunlight through. Using shade cloth over plants effectively keeps temperatures down.
For additional temperature control, raising the sides of the tunnel house will release any built-up warm air. In a more elaborate set-up, a mist system inside a tunnel house in addition to shade cloth will guarantee that the temperature will stay comfortable for your cool-weather plants.
Shade is Essential
Another way to achieve success with cool-weather plants in the heat of summer is to use natural or man-made shade. If you have an area that’s shaded during part of the day, try planting cool-weather crops there. Try to pick an area that is shaded during the afternoon to help keep the intense afternoon sunlight and heat off your cool-weather crops.
A third way to keep these plants cool is simply to put a roof over them. Drive four stakes, T-posts, or fence posts into the ground and suspend shade cloth or a lattice across the tops of the posts. This “roof” will provide filtered shade while still letting rainwater through.
Keep your spring vegetable crops as cool as possible by offering the plants shade, plenty of water and top dressing the soil around your plants with one to three inches of finished compost. This is the key to successfully growing cool-weather crops in the heat of summer.