Grand Rapids Lettuce

Lettuce requires well-drained, nutrient-rich soil with a pH between 6.0 and 7.0. The soil should be loose and friable, with plenty of organic matter. Lettuce prefers cool temperatures and can tolerate partial shade, but it needs at least six hours of sunlight per day to grow and mature properly. In hot climates, lettuce may benefit from afternoon shade or planted in a location with filtered sunlight. Proper watering is also essential for lettuce, as it prefers consistently moist soil without standing water or excessive moisture.

After danger of frost has passed, sow seeds 4-6" apart, 1/8" deep in rows 18-24" apart. Under ideal conditions, germination will occur in 7-14 days. Can also be started indoors about four weeks before the last frost.

Harden off seedlings for at least three days before transplanting. Set transplants outdoors just before the last frost, spacing plants 6" in all directions. Water regularly until seedlings are well-established.

Insect Pests

Although pests are not usually a problem for lettuce, slugs can sometimes damage leaves. Slugs can be controlled by handpicking or by sprinkling diatomaceous earth around the base of plants.

Diseases & Other Problems

Lettuce is usually not affected by disease, however the plants are heat-sensitive and may bolt prematurely during heat spells. Additionally, certain varieties do not germinate well in hot soil. Be sure to select the right variety for the planting season and always keep soil moist during germination.

To harvest lettuce, wait until the leaves have reached their desired size and use a sharp knife or scissors to cut the leaves at the base of the plant. For loose-leaf varieties, harvest outer leaves regularly to promote new growth. To store lettuce, rinse the leaves in cool water and dry them thoroughly with a salad spinner or by patting them gently with a towel. Then, wrap the leaves in a dry paper towel and store them in a plastic bag or container in the refrigerator for up to a week. It's important to avoid crushing or bruising the leaves during storage, as this can cause them to spoil more quickly.

CONSIDERATIONS:

Lettuce is an inbreeding plant and therefore does not require isolation, however the flowers can be visited by insects and therefore crossing is possible. Most commercial growers separate by at least 25' and report fewer than 5% outcrossing between lettuce varieties. The USDA recommends at least 12'. To ensure varietal purity when space is limited, avoid planting similar varieties in close proximity, which would make it difficult to identify outcrosses among the progeny.

HARVESTING SEED:

Lettuce seeds ripen irregularly and are ready to harvest beginning two weeks after flowering. To harvest, shake heads into a paper bag daily until a sufficient amount of seed is collected (note that at least half of the volume will be chaff). As the seeds and chaff are similar in weight, winnowing can be challenging. Instead, it is best strain the seeds through a screen to remove some of the chaff. Some debris will remain, but this is usually not a concern for home gardeners.

SEED LONGETIVITY:

Lettuce seeds ripen irregularly and are ready to harvest beginning two weeks after flowering. To harvest, shake heads into a paper bag daily until a sufficient amount of seed is collected (note that at least half of the volume will be chaff). As the seeds and chaff are similar in weight, winnowing can be challenging. Instead, it is best strain the seeds through a screen to remove some of the chaff. Some debris will remain, but this is usually not a concern for home gardeners.