Tips for Growing Lettuce

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By Susan Littlefield

There are few things more welcome to winter-weary gardeners than the first signs of spring in the plant world -- buds swelling, asparagus tips poking through the soil, the cheerful blossoms of crocuses opening their faces to the sun. And there are few things that taste better to a vegetable gardener than the tender lettuce and greens of the season's first homegrown salad. There is a wide variety of lettuces and greens that thrive in cool spring weather. Now is the time to sow some seeds so you can soon be enjoying that delicious first harvest.

Types of Lettuce

If the word lettuce conjures up a plastic-wrapped head of iceberg on a supermarket shelf, you are in for a treat. There are many different kinds of lettuces and and salad greens that are easy to grow and provide a nutritious, attractive, and tasty mix for your salad bowl.

Leaf lettuces are fast growing plants that are ready for harvest in as little as 45 days, even less for a light harvest of baby leaves. Leaves may be bright green or rich red, and have wavy or notched edges. You can harvest the entire plant or extend your harvest by selectively picking the outer leaves.

Butterhead lettuce, also called bibb or Boston lettuce, has especially tender, succulent leaves that form a loose head. The leaves of some varieties are tinged with red.

Head lettuce includes the familiar' Iceberg' variety and forms a firm head of crisp, juicy leaves.

Romaine lettuce is also known as cos. It forms a loose head of sturdy, elongated green leaves. Romaine and leaf lettuce are the highest in nutrition among all the lettuces.

Salad greens such as arugula, corn salad and mizuna are cold-tolerant and easy to grow, offer an early harvest, and add zest, nutrition, and interest to your salad bowl.

Getting Started with Lettuce

Lettuce is tolerant of cool soil and cool weather, so you can plant seeds in a well-prepared seedbed as much as 4 weeks before your last frost date. Lettuce seeds are small, so make sure you have raked the seedbed smooth and removed stones and large clods of soil so the germinating seeds can shoulder their way through to the surface.

Wide row planting works well for a lettuce crop. Simply scatter the seeds thinly over the surface and just barely cover them with soil; the seeds need light to germinate. Keep the seedbed moist but not soggy until seeds sprout. Then you'll need to thin, beginning when the seedlings have several sets of leaves. But all those tender young thinnings needn't go to waste; just toss them into the salad bowl. Follow the directions on the seed packet for the correct spacing for the kind of lettuce you're growing.

To keep your harvest going and to make sure you have enough, but not too much, lettuce ready to pick at any one time, make successive, small sowings every 10-14 days.

Start Lettuce Seeds Indoors

Many gardeners like to start their lettuce seedlings indoors. This gives you a little bit of a jump on the season and allows you to space seedlings precisely in the garden without the chore of thinning. Start seeds indoors about 4-5 weeks before your last frost date and set hardened off seedlings in the garden when seedlings are several inches tall.

You can continue to make successive sowings in pots for transplants even as the weather warms to make it easier to place individual plants in the garden. When the weather gets hot, lettuce will bolt or go to seed, becoming bitter and inedible. For summer harvest, choose varieties that have been selected to be bolt-resistant, and locate plants where they get some afternoon shade from taller crops.

While you can start your seeds indoors, lettuce and salad greens needs full sun for optimal growth. For best results on growing lettuce indoors, use a grow light, or place in the sunniest window available. Also, make sure that the soil stays moist (but not wet) . You'll be eating young leaves in 3-4 weeks. 

How to Harvest Lettuce

Harvests of leaf lettuce and greens can begin as soon as the leaves are a usable size. You can simply pinch the outer leaves off gently or use a small pair of scissors to clip them off. Or you can let plants reach full size, then harvest by cutting off the entire plant at ground level. By harvesting the outside edges, leaf lettuce will continue to produce new leaves until the weather is warm enough to trigger the plant to bolt. 

Heading lettuces like butterhead, iceberg, and romaine are ready to pick when the heads are firm and full sized. But if hot weather is on the way and you are concerned that plants will bolt, it's best to harvest them even if they haven't yet headed up completely.