Succession planting is the planting of a new crop, directly after harvesting the previous crop, in the same space. This technique allows you to grow more crops using less space. One reason why greenhouse gardening in succession is a good idea is it allows you to grow and harvest fruits, herbs, vegetables and flowers year-round. Greenhouse gardening also allows crops that might not grow in your area at all to be successful.
Determine the crops you wish to grow. Tomatoes, peppers, eggplants, exotic fruits and some flowers such as roses will require additional heat in cool climates to keep them alive and productive through the winter. Consider the water requirements of plants you choose to grow. In a warm greenhouse, setting up a hose is possible. However, if the greenhouse is not heated, it will be necessary to carry water as needed to keep the cool-season crops alive.
Tips for Succession Planting
Get the most out of succession planting by staggering planting dates. Do not plant more than you will use during one harvest unless you intend to sell, donate or preserve it. Plant a second, different crop in the extra space. Read the seed packets and look for maturation dates. Plant radish around young cucumber plants, then harvest the radish before the cucumbers need the room. Consider what plants are companion plants, or grow well together, and make a plan on paper. Choose crops that do well during certain times of the year, since even with heat, greenhouses cool considerably at night.
Early Spring Crops
Early spring crops are ideal for an unheated greenhouse. The sun will warm the inside of the greenhouse, making it possible to grow carrots, lettuce, onions, spinach, radish, peas and a host of other early spring crops. Lower light levels and the occasional freeze will not harm these types of plants, according to Colorado State University Extension. Once the air temperature warms up inside the greenhouse, the crops will thaw and the quality of the produce will be the same.
Shade is required for most summer crops grown in a greenhouse so they do not burn up. Covering the greenhouse with shade cloth is the easiest way to accomplish this task. Choose warm-weather crops, such as peppers or exotic fruits or flowers, to replace the early spring crops. Keep the soil cool by watering daily and using mulch. Ventilate the summer greenhouse by using fans, or opening the greenhouse windows, doors and vents, to allow better air circulation and keep temperatures down.
Fall and Winter Crops
Many crops, such as arugula, garlic, mache, turnips, mustard and spinach, will survive the winter even if the greenhouse is not heated. Start the seeds of these plants in flats, in late July or early August. Remove the summer crops, and then transplant the young seedlings. Fall and winter crops highly benefit from the use of row cover, sometimes called frost cover. This is a lightweight polyester or polyethylene fabric that allows light and water through, but insulates the plants from extreme cold temperature and protects them from frost.