Growing Lettuce & Spinach
Posted: April 19, 2012
Types: Lettuce is divided into two types, head and leaf. Head lettuce requires more maintenance and is more difficult to grow than leaf lettuce. As opposed to leaf lettuce, once a head of lettuce is harvested, a new head will not grow. Spinach is differentiated by leaf type—crinkled leaf, savoy, and plain leaf.
When to Plant: Both lettuce and spinach grow well in temperatures ranging from 50 to 70°F, with ground temperatures ranging from 35 to 45°F. Once daytime temperatures reach 80°F and above, the plants tend to bolt, or go to seed, and the taste becomes bitter. In early spring, sow lettuce seeds in the garden up to 4 weeks before the last spring frost. Spinach can be sown even earlier, generally up to 8 weeks before the last spring frost. However, these times are approximations since the soil must be dry and workable before any seed can be sown. In our area, a good time to sow spinach is in early April for harvest by the end of May. Lettuce seed can be sown in mid-April for harvest in the beginning of June. Successive weekly plantings until late May or early June will provide a continuous harvest until daytime temperatures become too high. Both prefer a loose, fertile, loamy soil, heavy with organic matter, with a pH of 6.0 to 6.5.
How to Plant: Both lettuce and spinach can be sown directly into the garden, as neither transplants well. Seeds can be either broadcast over an area no more than 12 to 15 inches wide, to allow easy maintenance, or sown in rows. Seeds should be covered with 1/4” to 1/2” of soil. Some lettuce seeds require light for germination, so be sure to read the instructions on the seed packet. Lettuce and spinach can be grown in containers; placing the containers in shaded areas during the hot hours of the day will prolong the growing season.
Care: Plants should be watered deeply, once a week, if no rain is forecast. Mulching also helps to conserve moisture. However, be careful not to overwater, which can lead to disease problems.
If you are unable to perform a soil test to determine your fertilizer needs, as a general rule of thumb use 3 to 4 lbs. of a 5-10-10 fertilizer per 100 square feet of garden. Thin seedlings to allow room for growth, and use these young leaves in a salad as they are at their most tender and delicious.
Harvest: Leaf lettuce may be harvested at any time during its growth; it will continue to produce new leaves as you harvest leaves from the outside. Head lettuce should be harvested when the heads are full-sized. Spinach is mature when it has a rosette of 5 to 6 leaves. Entire plants can be cut at the soil line, as spinach does not produce new leaves. Both spinach and lettuce tend to become bitter and woody the older they get.