Growing Organic Lettuce

WHEN TO PLANT LETTUCE

Lettuce can be planted directly in the ground in early spring when the soil temperature reaches a minimum of 35°F. Although the optimal temperature for germinating the lettuce seed is 75°F (which you can achieve by starting your seeds indoors- see 'Starting Indoors'), the seeds will still germinate in colder temperatures; it will just take a little longer for germination to occur.

Lettuce can tolerate light frost but if a cold frost is predicted, cover plants with a row cover to prevent freezing. When temperatures reach over 80°F the heat will cause the seed to become temporarily dormant and germination will not occur.

To have a steady supply of lettuce available throughout the season, plant seeds every ten days to two weeks. You can continue planting until heavy frosts begin to hit in the fall but if you have a cold frame you could even stretch your lettuce season a little further depending on your climate.

LIGHT AND WATER REQUIREMENTS

Lettuce, in the spring does best in full shade but once the summer heat hits, it will perform better if it is in partial shade. When planting consecutively, begin planting your seeds in partial shade starting late spring. Giving the plant some relief from the hot sun will slow the "bolting" process (when a plant begins to flower and produce seed) which also causes the lettuce leaves to become bitter.

To slow down the bolting process, once it starts go grow upward, break off the top center of the plant before it goes to seed. Lettuce needs a steady supply of water but not a heavy amount. If the soil becomes dry the lettuce will not only stop growing but it will cause the leaves to have a bitter flavor.

PREPARING THE SOIL FOR PLANTING LETTUCE

Lettuce has a short, dense root system. Because the roots don't go down very deep, it is important that you plant it in humus-rich (humus is dark organic matter which may contain compost or aged manure), well-drained soil.

Test the pH level in your soil; lettuce requires a pH between 6.0 - 6.8. Lettuce likes high levels of nitrogen and a steady dose of it so apply a natural quick release form of nitrogen such as blood meal or compost tea and a slower release form such as composted manure or alfalfa meal to keep the nitrogen supply steady throughout the growing season.

STARTING LETTUCE INDOORS

For an even earlier crop, lettuce seeds can be started indoors up to 4-6 weeks before your area's last frost date. With lettuce seeds, light is the most important element for germination so keep trays in a sunlit area or under grow lights.

PLANTING LETTUCE SEEDS DIRECTLY IN SOIL

When planting lettuce seeds, you can either broadcast seed and lightly rake to cover them or plant seeds in rows ¼ inch deep 1" apart. Lettuce seeds are very small and often hard to control the amount when planting. Rolling them between your index finger and thumb gives you a little better control.

Once your lettuce has grown four leaves, thin your plants to remove excess plantings and allow room for growth. Allow 12-14 inches between plants when growing head lettuce (such as Iceberg and summer crisp types), and 4" between plants if you're growing leaf lettuce.

We've found that a simple liquid organic leaf spray called Organic Garden Miracle™ not only speeds up the lettuce harvest (some have said up to 50% but I haven't personally verified this), it improves the sweetness and flavor of your lettuce as well.

COMPANION PLANTING AND ROTATION CONSIDERATIONS

The best companions for growing lettuce are carrots, garlic, onions, and radishes. Lettuce does not seem to have any enemies and can be planted next to any vegetable or flower plant.

Attractive hint: a row of rotating red and green varieties can make an eye-catching and nutritious border in your flower bed or a nice accent in your containers.

When you're growing lettuce, it's best not to plant it where radicchio, artichokes, or endive grew the previous year. To prevent disease issues, plant in a location where lettuce has not been grown in three years.

WHEN TO HARVEST LETTUCE

If you want more crisp lettuce leaves, harvest it in the morning. Lettuce becomes more crisp during the cool hours of the night. You can begin to harvest outer lettuce leaves (except for head lettuces) when they are large enough for a salad - about 6" tall or when the stability of the plant is not weakened by the removal of a few outer leaves. Continue to harvest until a center stock forms.

If harvesting full lettuce heads, cut the head at the base 1 inch above the soil level and a new head will begin to develop. Depending on the growing season, you may be able to get a third harvest. Once a center stock begins to form, the plant is beginning to bolt, and the leaves develop a bitter flavor that are no longer good for eating.

STORING LETTUCE

Eating lettuce fresh from the garden provides the best flavor and quality, but if you keep it in a plastic bag free from moisture, most lettuces will last 1-2 weeks. Lettuce cannot be stored long-term.

SAVING SEEDS

To keep your seeds pure, plant lettuce varieties a minimum of 12 feet apart to prevent cross-pollination. Save seeds from the last plant to bolt since early bolting is a negative trait that will carry through to the seeds.

Lettuce seeds are ready for harvest 12-24 days after flowering. Seeds will not all ripen at once so to get the highest quantity of seeds from your plant, shake the seed heads into a large paper bag once a day during the ripening process and keep the bag stored in a dry location at night.