Lettuce is a well-known cool weather crop. Its seeds germinate at soil temperatures as low as 40 degrees, its seedlings tolerate a light frost and overwintered fall plantings produce tasty new leaves as the weather warms in spring.
But did you know that with a little effort you can grow lettuce year-round? Read on.
Lettuce is one of the first crops planted in local vegetable gardens in the spring. You can start seeds indoors four to six weeks before the projected last frost date, but direct sowing in the garden is easier and can occur as soon as the ground can be worked.
Plant lettuce in full sun, in a well-drained soil, high in organic matter. Since lettuce seeds are small, break up dirt clods to improve contact with the soil and germination.
Lettuce seeds may be sown in single rows or broadcast for wide-row planting. Cover the seeds with one-eighth to one-quarter inch of soil. Be careful not to bury the seeds too deeply as lettuce seeds need exposure to light to germinate.
For best production, thin seedlings after they have developed a few leaves. Thin leaf lettuces (lettuce that does not form a head) to 4 inches apart and headed varieties to 8 inches apart or more depending on head size.
Because lettuce roots are relatively superficial, water them when the soil surface dries. Unlike most vegetables, it is more important to water lettuce frequently than deeply.
Lettuce needs nitrogen to grow tender, new leaves quickly, so fertilize throughout the growing season with a balanced fertilizer.
Once your lettuce gets going, don’t wait too long to begin harvesting; lettuce is best when it is young and tender.
Harvest leaf lettuce by simply removing the outer leaves, leaving the central bud to grow more leaves. Harvest head-type lettuces by removing the outer leaves, digging up the whole plant or cutting the plant about an inch above the soil surface. With the latter, a second harvest is often possible.
As the weather warms, lettuce tends to become bitter and tough. But you can grow lettuce in summer by altering the temperatures around your planting and selecting heat-tolerant varieties.
Plant summer-seeded lettuce where it will get morning sun and afternoon shade. If you cannot identify a garden spot with these conditions:
• Plant lettuce in the shade of taller plants such as tomatoes and pole beans,
• Erect a shade cloth over the planting, or
• Plant in pots that can be moved to a part-shade location.
Open-leafed varieties are the most heat-tolerant lettuces, although butterheads do fairly well. Romaine lettuces are the least heat tolerant. Because darker lettuces absorb more sunlight, choose light green varieties over dark red ones in the summer.
As the weather cools, lettuce is back in its element. Plant a fall crop about four to eight weeks before the first frost. “Winter density,” which has compact, extra-dark green heads, performs well as the weather cools. If you use a cold frame or row cover to protect the plants from rain and snow, you might be able to keep fall-planted lettuce producing through the winter.
Homegrown lettuce tastes better than supermarket lettuce, so keep your salad-eating family happy and grow lettuce all year-round.
For more gardening information, tune into KSQM (FM 91.5) every Friday at 6:40 p.m. when Clallam County Master Gardeners talk about selected gardening topics. If you miss a broadcast don’t worry; the show repeats the following Tuesday at 11:40 a.m.
Pearl of wisdom
Most gardeners plant too much lettuce at once and much of it goes to waste. For a family of four average salad eaters, plant no more than a 3-foot row of lettuce at a time; sow additional seeds every two weeks (switching to heat-tolerant varieties in late June and winter-tolerant varieties in August).
Jeanette Stehr-Green is a WSU-certified Clallam County Master Gardener.
Grapefruit, Nut and Lettuce Salad
Lettuce is a low-calorie source of fiber, vitamin A and vitamin K. The darker green the leaf, the more nutrients it provides. Instead of using high calorie dressings and other fatty salad fixings, opt for a light vinaigrette and a sprinkling of chopped nuts for added crunch and protein, as in this recipe.
1 small red grapefruit
2 Tablespoons olive oil
1/2 teaspoon sugar
1/8 teaspoon salt
1/8 teaspoon black pepper
4 cups torn leaf or Bibb lettuce
4 Tablespoons chopped nuts (walnuts, pecans or almonds)
4 Tablespoon feta cheese (optional)
Peel and section grapefruit. Remove and discard membranes. Squeeze and reserve juice from one or two grapefruit sections. Break remaining sections into bite-sized pieces. Combine juice, olive oil, sugar, salt and pepper stirring with a whisk. Divide lettuce evenly among four plates. Sprinkle
1 Tablespoon of chopped nuts and 1 Tablespoon crumbled feta (optional) over each salad. Divide grapefruit pieces evenly among salads. Drizzle with olive oil mixture. Makes four servings.