How to Grow Lettuce from Seed
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How to grow lettuce from seed is mostly a matter of temperature, depth and thinning. Lettuce is a cool-season crop that sprouts in mild soil but runs to seed in summer heat, so timing decides both the harvest and the flavor. The university guides below agree on shallow sowing, steady moisture and thinning. They differ on spacing, which depends on the type of lettuce, so this guide gives the figures for each type. Nothing here recommends a product.
Quick answer
- Sow seed about one-quarter inch deep, and cover it with potting soil if your garden soil tends to crust, as the Clemson guide advises.
- Thin leaf lettuce when the seedlings are one to two inches tall, leaving four to eight inches between plants, depending on the variety.
- Sow in cool weather. The Clemson guide gives 60 to 80 °F for germination and 55 to 65 °F for steady growth.
- Give at least six hours of direct sun, and use shade cloth or tall crops to ease the afternoon heat in summer.
Sow when the soil is cool and workable
Timing starts with soil temperature. The University of Maryland guide says to sow leaf or butterhead types “as soon as soil can be worked in the spring”, and it allows a second sowing in late summer. The Clemson guide gives the germination window as 60 to 80 °F, and it warns that “Raw lettuce seed will not germinate at a soil temperature above 95 °F.” Soil that hot will stop germination, so wait for cooler weather before you sow.
The Maryland guide says crisphead and cos types may be transplanted in early spring and fall. That split matters for a home grower. Loose-leaf types suit direct sowing, while head lettuce is best started from transplants, which the Clemson guide recommends when it says “It is best to grow head lettuce from transplants”, meaning plants bought from a reputable garden center.
Sow shallow and cover the seed well
Depth is the first detail to get right. The Clemson guide says to plant leaf lettuce in rows 1 to 2 feet apart with “seed one-quarter inch deep”, and it notes that small seed is hard to space precisely. Sow thinly and cover lightly.
Soil surface matters too. The Clemson guide says that “Covering the seed with potting soil instead of garden soil will eliminate crusting problems”, and it adds that heavy clay soils are the most likely to crust over developing seedlings. The guide recommends a loamy soil with plenty of organic matter for lettuce in the first place.
The Maryland guide gives a sowing rate for leaf types: “Sow 10 to 20 seeds per foot of row.” Thin afterward rather than trying to space each seed exactly. The Clemson guide describes that approach as usually necessary: “it will usually be necessary to plant thicker and thin the planting.”
Spacing by type
The spacing figures depend on whether you are growing leaf, cos, butterhead or crisphead types. The table below sets out the figures from each guide that gives one. Where a guide gives no figure for a type, the cell says not stated.
| Type | Maryland spacing in the row | Maryland spacing between rows | Clemson guidance |
|---|---|---|---|
| Leaf | 4 to 10 in | 12 to 24 in | Seed 6 to 10 in apart in the row, rows 1 to 2 ft apart |
| Cos or butterhead | 4 to 10 in | 12 to 24 in | not stated |
| Crisphead | 12 to 15 in | 20 to 30 in | Head lettuce in rows 3 ft apart, 12 in between plants (transplants) |
The Iowa State guide, which covers leafy greens in general, suggests sowing “in wide, banded rows 12 to 24 inches apart” to use garden space well. Those banded rows suit a bed of mixed leaf types. For leaf types, the Maryland guide adds a thinning figure: “Thin individual plants 4- to 8-inches apart, depending on variety.”
The two sets of numbers answer different questions. Clemson gives the sowing spacing for leaf seed, and Maryland gives the final spacing after thinning. Use the Clemson figure to plan the sown row and the Maryland figure to plan the plants you keep.
Thin the seedlings in two steps
Thinning is where most seed-grown beds succeed or fail. The Clemson guide says “Leaf lettuce should be thinned when the plants are 1 to 2 inches tall.” That gives the first thinning a clear timing, and it means the seedlings are large enough to pull without disturbing the ones you keep.
The Maryland guide points to a shortcut. It says “3 to 4 week old transplants can produce earlier harvests”, and that they eliminate the need for thinning. If you want an earlier harvest and fewer thinning passes, grow transplants until they are three or four weeks old, then set them out as the guide describes.
Light, shade and heat
Lettuce needs sun, but not always the full afternoon. The Iowa State guide says leafy greens “grow best in full sun, well-drained soil, and cool temperatures”, and it adds “Provide at least six hours of direct sunlight a day for best growth.” The Maryland guide says lettuce “Tolerates partial shade” but grows well with full sun in spring and fall. The Oregon State container article says that “Root and leaf crops (beets, turnips, lettuce, cabbage, mustard greens) can tolerate light shade.”
Summer heat is the main limit. The Maryland guide says “Increasing day-length and high summer temperatures usually cause seedstalk formation (bolting) and bitter flavor.” Plant successive crops in spring and use tall crops or trellises to shade the late spring planting from direct afternoon sun, as the same guide suggests. Shade cloth is another option, since the guide notes that it “can help to protect summer-grown lettuce from direct sunlight and high temperatures.”
Interplanting also helps. The Maryland guide describes planting lettuce between rows or within the row of later-maturing crops as a space-saving practice. For a short list of other crops that share a bed well, see vegetables that grow well together in raised beds.
Water steadily and in the morning
Lettuce wants steady moisture while the seedlings establish. The Maryland guide says “Use frequent, light watering to encourage rapid growth”, and it warns against over-watering. The Clemson guide sets a depth target: “Water the garden sufficiently to moisten the soil to a depth of 6 inches.” It also warns that light sprinklings encourage shallow rooting, so the watering should reach down into the bed.
Timing matters as well as the amount. The Maryland guide says overhead watering “should always be done in the morning”, which gives plants time to dry off during the day. The Clemson guide adds that “Lettuce seedlings should be protected from the wind”, because young plants dry out rapidly, which is one more reason to keep young seedlings moist and sheltered.
Weeds and young seedlings
Weeds compete hard with young lettuce. The Clemson guide says “Lettuce seedlings are poor competitors with weeds”, and it adds that “weed control is very important with this crop.” Cultivate shallowly when you weed, since the same guide warns that “Cultivation for weed control should be shallow to prevent root injury.” Pulling weeds by hand near the seedlings is the gentler choice when the row is still young.
Start seed in a container
A pot works well for lettuce. The Iowa State guide says “Any container six to eight inches in diameter or larger can be used”, and it notes that window boxes work particularly well for leaf types. The Oregon State container article says to “Plant seeds according to packet directions”, and it adds “After planting, water gently so you don’t wash seeds out.” The same article notes that “Containers dry out quickly, especially on concrete in full sun”, so a pot in full sun needs close watching.
The Oregon State guide lists lettuce among the root and leaf crops that tolerate light shade, so a pot of lettuce can sit where it gets a little less sun than a fruiting crop needs. For easy vegetables that suit a raised-bed layout, see easiest vegetables to grow in raised beds.
Avoid bolting and bitterness
Heat and day length drive bolting, and bitterness follows. The Clemson guide notes that “Slow-bolting or heat-resistant varieties are available” and recommends them for extending the lettuce season. It also says that “Bibb lettuce will develop bitterness readily if temperatures go above 75 °F.” Choose slow-bolting types for the summer sowings, and keep bibb-type lettuce cooler if you can.
Successive sowing spreads the risk. The Maryland guide says to “Plant successive lettuce crops in spring”, and it adds that some cultivars may overwinter when healthy three-week-old transplants are set out around October 15. That overwintering advice is for Maryland conditions, so check the date for your own area before you try it.
Harvest leaves early and often
Harvest leaves before the plant heads or bolts. The Maryland guide says that leaf lettuce “can be used as soon as plants are 5 to 6 inches tall”, and it advises taking the older, outer leaves first. The Clemson guide puts leaf lettuce at “about 75 days after planting” when it is ready to harvest, which gives a useful planning figure for a sowing date.
Cut-and-come-again harvesting suits leaf types. The Maryland guide describes cutting plants right above the ground when they are 6 to 10 inches tall, so they regrow for a second harvest. Plan a new sowing before the first one is used up, so the bed keeps producing.
What we could not verify
The sources cover the basic steps well, but several points remain open. Spacing is the largest gap, since the Maryland and Clemson figures do not agree for leaf types. Germination time in days is also missing, because the pages give a temperature range rather than a number of days.
What the sources do not say
None of the four pages gives a days-to-germination figure for lettuce seed, so this guide gives temperatures instead. The Iowa State page covers leafy greens in general, so its light and spacing advice is a close fit for lettuce rather than an exact one. The Oregon State container article covers vegetables in general, not lettuce alone. The Clemson guide gives a 6 to 10 inch sowing spacing for leaf seed, while the Maryland guide gives 4 to 8 inches after thinning, so the two numbers describe different stages of the same row.
How we chose
The guide relies on four pages: two university extension guides on lettuce, one from Iowa State on leafy greens, and one Oregon State article on growing vegetables in containers. All were opened with curl on 2026-10-23 and all returned HTTP 200. The guide uses only what those pages state, and each figure carries its source. It names no seed varieties or products, and it treats no retail listing as a source.
Frequently asked questions
How long does lettuce take to grow from seed?
The Clemson guide says leaf lettuce should be ready to harvest about 75 days after planting. That figure is a planning estimate for leaf types, and the pages reviewed here do not give a separate figure for head lettuce or for seed sown in a pot.
Can lettuce seed sprout in hot soil?
Not well. The Clemson guide gives 60 to 80 °F as the optimum germination range, and it warns that raw seed will not germinate above 95 °F. The same guide says to use primed seed if possible, since priming is meant to give good germination at varying temperatures.
Should you start lettuce indoors or sow it directly?
Both work. Sow leaf types directly in spring or late summer, as the Maryland guide describes. If you want an earlier harvest and less thinning, the same guide says three- to four-week-old transplants can give both, and the Clemson guide recommends transplants for head lettuce.
Why did my lettuce turn bitter?
Heat and long days are the usual cause. The Maryland guide links high summer temperatures and day length to bolting and bitter flavor. The Clemson guide adds that bibb lettuce turns bitter once temperatures rise above 75 °F.
Does lettuce need full sun?
It does best with plenty of light. The Iowa State guide suggests six hours of direct sun for leafy greens, the Maryland guide says lettuce tolerates partial shade, and the Oregon State article lists lettuce among crops that tolerate light shade. Aim for the sunnier end of that range in spring and fall, and provide shade in summer.
Sources
- https://extension.umd.edu/resource/growing-lettuce-home-garden (opened 2026-10-23)
- https://hgic.clemson.edu/factsheet/lettuce/ (opened 2026-10-23)
- https://yardandgarden.extension.iastate.edu/how-to/growing-leafy-greens-iowa (opened 2026-10-23)
- https://extension.oregonstate.edu/es/node/146716/printable/print (opened 2026-10-23)
