Lettuce is one of the most successful crops for the home gardener. There are four basic of types of lettuce. 1. Leaf lettuce such as ‘Black Seeded Simpson’ and ‘Oakleaf’ that produce large heads. The plants mature in 40 to 45 days but individual leaves can be harvest throughout the growing season. 2. Butterhead, also known as Boston or Bibb, s matures in 65 to 80 days. The heads are loose and open and have a creamy color inside. 3. Romaine/Cos famous for its use in Caesar salad, matures in 70 days if summer planted, 80 days if spring planted. The heads are cylindrical and the individual leaves are easily separated. 4. Head lettuce such as ‘Iceberg’, matures in 80-95 days, has compact heads, and is very heat sensitive. Lettuce thrives in full sun and nitrogen-rich, moist, well-drained soil that is well-limed.
Lettuce is a cool weather crop and will not germinate at temperatures over 80 F. In addition, as summer temperatures rise the leaves become bitter and the plants bolt. Loose-leaf varieties are less heat sensitive than other lettuces and generally are more successful in warm climates. The key to successful lettuce growing is an early start. Looseleaf lettuce grows so quickly that it is usually direct sown in the garden before the last frost as soon as the soil can be worked. It can also me sown outdoors in the fall for a winter crop in mild climates. Starting it indoors four to six weeks before the last frost is possible and produces an early crop. Butterhead, romaine, and head lettuce are best started indoors six to seven weeks before planting outdoors so they can have sufficient time to form large heads.
1. Plant seed in flats covering with 1/8 to ¼ inch of soil.
2. Place in an area where temperatures are between 40 and 80 F and keep moist. Germination should occur in three to ten days depending of the temperatures.
3. Thin plants to two to three inches apart.
4. When the soil can be worked, harden off the plants for two to three days.
5. Transplant the seedlings to the garden eight to ten inches apart for leaf types and eight to twelve inches for others. Pull off the outer leaves as you plant.
6. Protect young plants if a severe frost threatens.
Heat and long day cause lettuce to bolt no matter what you do. Mulching will help keep the soil cool (but will attract slugs). Out door lighting that is on at night, however, can aggravate the problem of bolting so plant lettuce away from light sources.