Gardening Articles: Care :: Plant Care Techniques
Growing Head Lettuce
by National Gardening Association Editors
A lot of people think that crisphead or iceberg-type lettuce is hard to grow. It's not. Good head lettuce just needs fertile soil, ample sunlight, a good supply of moisture and nutrients and most important, cool weather. The plants need temperatures around 55F to 60F during the growing season, so for most gardeners this means starting plants early indoors or planting in summer or fall for a fall or winter harvest, depending on your climate.
Start seedlings indoors in late winter, six to eight weeks before the average date of the last spring frost. Plant the seeds in shallow seed boxes or "flats." Put the tiny seedlings in a sunny spot and keep them watered. About six weeks later, the plants are big enough to set in the garden. But before you do that, harden the plants off to get them ready for outdoor living. Place them in a protected spot outside for a few hours a day, lengthening the time they spend outside until they're out there all day.
You can start head lettuce in cold frames if you live where the nights aren't too chilly in early spring. Gardeners in mild winter areas or where the springs are long and cool can sow head lettuce seeds directly in the garden.
Some varieties are noted as "heat resistant" in the seed catalogs. These are worth trying if hot weather comes too quickly in your area. High temperature over a period of time is nothing but trouble for head lettuce. The heads lose their firmness, the leaves get bitter, and diseases may erupt. So, keep cool - by using mulch, starting seeds indoors and planning a fall head lettuce crop.
Transplanting Head Lettuce
Transplant the young lettuce seedlings to the garden when the danger of real hard frost is past. They'll take a light freeze if they're hardened off properly. Place the plants 10 inches apart from each other in 20-inch-wide rows. Start harvesting heads when they're about the size of a softball. If you wait until the first head you harvest is the size of a basketball, they'll all be that big on the same day.
When setting the plants out, dig all the holes for them at one time, using a 10-inch scrap of wood to measure quickly the distance between holes. Dig each hole four to five inches deep. In the bottom of each hole put a tablespoon of 5-10-10 fertilizer or a small handful of compost or dried manure, and cover it with two to three inches of soil.
Water the flats well with a mixture of fish emulsion and seaweed before transferring the seedlings to the garden. This helps to keep the soil around the roots and adds a quick fertilizer boost. Before you put them in the ground, strip the outer leaves off the plant. Don't touch the center sprout of the plant, though, because that bud will grow to form the head.
Trimming the foliage helps because some of the roots are killed in transplanting, and the smaller root system can't support all the top growth. The roots, which need time to recover, take hold and start to grow again, and find it easier at first to meet the demands of fewer leaves.
Set the plants at the same depth they grew in the flats and give them a gentle watering. Keep them well watered for a few days.