By Billie and Robert Nicholson
As the summer season draws to a close, many gardeners wish for a longer growing season. Never fear, the answers are here. There are several things that the everyday gardener can do to extend the growing season for our gardens. As the weather cools, it is time to select new seeds or slips to plant that can tolerate cooler temperatures. Just as in the spring we planted lettuce, radishes, beets and carrots, the same pattern can be repeated in the fall. In addition, you can add more cold tolerant vegetables that will produce leaves and roots to eat. These can be divided into temperature tolerances, for example:
- Low temperature tolerant plants that can grow outside but are very sensitive to frost
- Chicory, endive, escarole
- Parsley, cilantro
- Radishes, celery, bok choy
- Medium cold tolerant plants can grow outside but cover them as the temperature drops
- Chinese cabbage, sorrel
- Collards, kale, spinach
- Snow peas
- High cold tolerant may survive uncovered but can be protected by row cover
- Brussels sprouts
The most important factor is knowing when to plant in the fall. As the weather gets cooler and day length decreases, plant growth slows down and will eventually come to a stop when the day length gets below ten hours. In much of the US, land north of the 30º latitude has day length shorter than ten hours between mid-November and mid-January. Check your location here. Your goal is to get plants to maturity before that day length happens. If you get them nearly mature, they will hold in the ground until you harvest them. Review the maturation date on the seed packets and plant those seeds within a time that will work. You can vary planting days to stretch your harvest. Pay attention as the night temperature begins to drop. Cover plants that are most delicate upon threats of frost. Find your average frost dates here.
There are several techniques to protect plants as the temperatures drop.
- Plant your garden in a south-facing field. These beds will get more sun exposure and soil will retain heat longer each day.
- Protect from wind. Wind can cause more damage than cold. Planting near a protective wall, fence or hedge can raise the air temperature several degrees.
- Plant in cold frames. These boxes are constructed with slanted walls and designed to have a top cover made of plastic or glass. The top can be raised during the day and for watering, but can be replaced at night when temperatures may drop to the frost level. There are many ways to build cold frames, but the idea is to create a warm place for plants to continue growing. See “The Cold Frame Handbook”to get plans and more details.
- Use row covers. Made from wire or 1/2” PVC electrical conduit pipe bent into the ground. A 10’ pipe can be bent to cover a 5-6’ bed. Use sand bags to secure at each hoop or insert a small piece of rebar in each end. Cover with spun fabric, which is light-weight, translucent, and breathable. This will provide wind protection and increase ground temperatures 5-10º F. Fabric that is made to 1 oz. thickness allows 70% sunlight through. You can double this cover in real cold weather. Be sure to take it off during the warmest part of the day.
- Greenhouses are the final answer for those gardeners who feel the need for dirty fingers all year long. The sky is the limit for greenhouse kits. They can range in size from table-top starter boxes to arboretums. They can be attached or free standing. A greenhouse should be large enough to walk into. The frame cover can be plastic sheets, vinyl panels or glass inserts. You will need a source of water, vents and perhaps a fan to make it most useful. In locations that have harsh winters, use row covers in the green house. We bought a kit and had quite an adventure putting it together.
Billie and Robert welcome your questions or comments. You can reach them at BillieandRobert@RustyBuggy.com