Lettuce seed sprouts quickly in the right growing conditions.

How Long Does It Take Lettuce Seedlings to Sprout?

by Janet Beal

Growing fresh vegetables is an easy way to add wonderful flavor to your meals. Fast-growing lettuce is a great vegetable for beginning gardeners to grow from seed. Good growing conditions are easy to provide for this rapidly-germinating seed. Lettuce is great for container-gardening as well as in-ground planting. Include lettuce in your spring garden, and watch your family's enthusiasm for salads increase as you bring this versatile vegetable to harvest.

1. Germination

In good growing conditions, lettuce seed will germinate within two to 12 days, depending on variety. Loose-head varieties may sprout more quickly than heading types, but all seeds depend on similar soil, moisture and light conditions to support germination. Growers vary in their estimate of the percentage of lettuce seeds that will germinate per packet, but you can expect 75 to 80 percent of seeds packed for the current growing season to sprout. Rates decline each year, and a packet of lettuce seeds is usually viable for three years.

2. Soil Temperature

Lettuce (Lactuca sativa) is an annual vegetable, and many varieties of it can be grown throughout the U.S. A spring grower, lettuce requires soil temperatures between 50 and 70 degrees Fahrenheit for seed germination. Germination rates decline markedly above 70 degrees, and seeds are best planted outdoors two weeks after your growing zone's last frost date. If you are uncertain about soil temperature, many garden centers and nurseries carry inexpensive thermometers to take guesswork out of planting.

3. Soil Quality

Lettuce grows best in neutral to slightly acid soil, as do many other garden vegetables. Because lettuce seeds are small and fragile, the most important feature of planting soil is texture. Raking and screening soil before you plant lettuce ensures successful sprouting of these delicate seeds. One to 2 inches of fine soil in the bottom of your lettuce furrow and a 1/4-inch to cover your seeds create prime sprouting conditions. If your soil is heavy clay or drains poorly, dig in rotted leaf compost or and peat moss to improve drainage before planting. For starting your lettuce seed indoors, standard potting soil or soilless potting mixtures have the texture that let seeds sprout and root.

4. Moisture

Soil for sprouting lettuce seeds needs constant and consistent moisture. With good drainage, soil will remain moist rather than wet. Regular watering will keep the top of the soil from crusting, which can become too hard for seed sprouts to penetrate. A fast grower, lettuce will absorb a lot of water, but standing water can rot seeds.

5. Light

Lettuce seed needs light to germinate and grow successfully, while many seeds germinate in either light or dark conditions and some, like annual violas (Viola tricolor), germinate only if kept in the dark. Daylight is one reason to direct-seed lettuce into the ground. If you start seeds inside, you will need a sunny window that receives direct light or a grow-light.

6. Sprouting Stages

When lettuce and many other seeds sprout, the first foliage is a pair of small rounded leaves called cotyledon leaves, or seed-leaves. Cotyledon leaves are the plant's first food-source and enable the growth of roots and real leaves, but they sustain the plant for only a week to 10 days. Seeds started indoors will need to grow for between four and six weeks to sprout enough leaves to sustain plants in the garden.

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