Lettuce is one of the easiest and quickest crops to grow in your garden. It's so widely available that gardeners often overlook growing it, but it's gratifying to pick lettuce from your own plants. By mixing and matching varieties with interesting leaf colors and shapes, and planting throughout the season, you can have enticing salads for eight or more months from your garden. All you have to do is remember to keep planting and harvesting.
Here are some tips on growing great lettuce from spring until fall.
There are four types of lettuce; head, butterhead, romaine, and looseleaf. The best type for you depends on your taste and when you're planting.
Head lettuce is the type most people associate with salad bars. The leaves are pale-colored, tightly wrapped, and crisp. Heads are harvested when firm, and the inner leaves are often almost white. Some good varieties to try include 'Iceberg' and 'Great Lakes'. A variation on head lettuce is the butterhead type. Butterhead lettuce heads aren't as tightly wrapped so the leaves are greener. The inner head, though, still looks blanched to a pale yellow coloring. The leaves aren't as crisp as iceberg but are firmer than leaves of looseleaf lettuces. Some good varieties to try include the standard 'Buttercrunch', the small-headed, smooth-leaved 'Bibb', and the bolt-resistant, red-leaved 'Sangria'.
Romaine lettuce also forms a head, but the shape is more tall than wide. The external leaves are crisp, green, and sweet, while the internal leaves are blanched to a light green color. 'Parris Island Cos' is a widely grown variety. 'Verte Mar' is a French romaine that features smooth, tender leaves and a sweeter flavor than other romaines. 'Rouge d'Hiver' is a good red-leaved romaine variety.
Probably the easiest lettuce type for a beginner to grow is the looseleaf. You can harvest this type whenever the leaves are big enough to eat. These varieties don't form a head and grow more wide than tall. Plant loose leaf lettuce every few weeks throughout the growing season, and you'll have lettuce all summer long. Some varieties to try are the heirloom standard 'Black Seeded Simpson', the short, ruffled-leaved 'Salad Bowl', and the bolt-resistant, red-leaved 'Ruby Red'.
Planting & Thinning
Lettuce is a cool-season crop. Plant as soon as you can work the soil in spring. Direct seed lettuce in the soil or start seedlings indoors under lights. Unless you have sandy soil, create a raised bed that's 8 inches tall and no more than 3 to 4 feet wide. Amend the soil with compost and adjust the pH to between 6 and 7. Broadcast seeds lightly on top of the raised bed. This technique works well with all lettuce but is best for butterhead, romaine, and loose leaf lettuces that will eventually be spaced close together. Cover the seeds lightly with potting soil or sand, and keep moist. Within one week seedlings should appear. Head lettuce varieties are best transplanted as seedlings since they require wider spacing.
When direct-sown seedlings are 2 to 3 inches tall, thin them to 3 to 4 inches apart for looseleaf lettuce, 6 to 8 inches for romaine and butterhead, and 12 to 16 inches for head lettuce. Don't toss the thinnings. Save them to make a fresh salad or transplant seedlings into other areas of the garden to grow and increase your lettuce crop.
Since you are eating the leaves, and nitrogen helps leaf growth, be generous with your nitrogen fertilizer. Once the seedlings start growing side-dress lettuce plants every three to four weeks with a highly soluble, nitrogen fertilizer, such as fish emulsion. You can also apply soluble fertilizer as a foliar spray to quicken the results. Keep plants well watered and weeded for best growth. Lettuce leaves will stay crisp yet tender if the plants are healthy and don't have to compete with weeds.
Harvest looseleaf lettuce varieties as soon as the leaves are big enough to eat. Harvest butterhead and romaine varieties once a loose head has formed. Wait until a full head has formed to harvest head varieties of lettuce. You can harvest lettuce one of two ways. Harvest the whole plant by cutting it off at the base or harvest a few leaves at a time. Head lettuce should be harvested all at once, and sometimes new leaves will emerge after cutting so you can enjoy more lettuce in a few weeks. The other types can be harvested over a long period by removing the outer leaves as they grow to encourage more inner leaves to form and extend the harvest.
One of the best parts of growing lettuce is you can harvest within one month after sowing. Plant every few weeks starting in early spring until early fall to insure a continual supply. This technique works particularly well with looseleaf lettuce varieties. The key is to grow small quantities of lettuce each time you sow, so when one crop is finished, the next is ready for harvesting. Select the types and varieties you like, but also look for those adapted to the season they will mature in. For example, 'Bibb' lettuce likes cool weather, so plant it to mature in spring or fall. 'Sierra' can withstand the heat, so plant it to mature in midsummer.
QUESTION OF THE WEEK
White Stuff on Seedling Soil
Q. I started eight flats of seeds in my basement under grow lights using seed-starting mix. The germination rate has been excellent and the seedlings look healthy, but the top of the seed-starting mix is turning white. What is causing this and should I be concerned?
A. If you are fertilizing and watering from the bottom, then the white stuff could be a buildup of fertilizer. Water from the top until water runs out the bottom of the flat. This flushes the soil of any fertilizers that have built up in the media. Another explanation may be that you're overwatering and white mold is growing on the surface of the soil. Gently scrape the mold off the soil surface without harming the seedlings. To dry out over-moistened soil, place a small fan near the flats to blow air over the trays. In the future let the soil surface dry out slightly between waterings.