By E. VinjeTweet
A cool season, fairly hardy, annual, vegetable gardeners are growing lettuce for its edible foliage, which is 90% water, but offers plenty of vitamins A and B. A member of the Asteraceae family, it has been cultivated for ages, perhaps longer than any other vegetable crop. Young lettuce leaves are delicious in salads.
Lettuce will require partial shade in warm climates, rich, sandy soil and regular water. Work the soil thoroughly (break up any clumps and remove debris) prior to planting. If using seeds, rake the surface smooth. Transplants can tolerate a rougher planting bed. Dig in plenty of compost and soil amendments rich in nitrogen to promote good leaf development.
Tip: Consider adding kelp meal to planting beds. It’s chock-full of micro-nutrients and is especially good for supplying trace minerals to crops that will be consumed.
How to Plant:
Sow lettuce seed directly into prepared garden beds two to four weeks before the last expected frost. Try broadcasting seeds over a wide row and gently raking them in to a depth of 1/4 inch deep. Grow head lettuce, such as romaine and loose leaf varieties, by thinning crops gradually to allow the most robust plants to mature into heads. For a steady supply of leaf lettuce, plant every 10-20 days and remember to shade plants in the summer. To promote rapid growth, apply fish emulsion or other organic fertilizer once or twice during the growing season.
Tip: Avoid high heat and disturbing roots for a bumper lettuce crop. Mulching with organic compost will help deter weeds and conserve moisture loss.
Once lettuce begins to bolt (go to seed), the leaves will become bitter. Harvest outer leaves to encourage inner leaves to grow. Lettuce is crispest if picked in the morning. Use a sharp knife to cut heads just below the lower leaves, or pull them out by the roots. Head and romaine lettuce mature about 70 days from seed; leaf lettuce matures in about 40 days.
Insects and Diseases:
Protect lettuce from earwigs, aphids, slugs and snails, which can occasionally cause problems on the crop. Prevent foliage rot by providing good soil drainage and air circulation around crops.
Tip: To help prevent many fungal disease, water on bright sunny mornings, to allow the leaves to dry by evening.
Seed Saving Instructions:
There is only a slight chance of cross-pollination between lettuces. As a precaution, separate by 25 feet from other varieties that are going to seed. Allow plants to bolt and form seed stalks. Seed heads may need to be protected from bird damage and rain when drying. Seeds are produced over a 2-3 week period and will require repeated harvesting.