Vegetable · Asteraceae
Lettuce
Lactuca sativa
Keep it cool, moist, and growing fast, and lettuce hands you crisp salads in barely a month.
Full sun
Every 2–3 days
55–64°F · 13–18°C
45–75 days
Overview
Lettuce is the quickest reward in the vegetable garden, going from seed to salad in as little as 45 days. It belongs to the daisy family and grows as a cool-season annual, happiest in the mild stretches of spring and fall. You can grow it in a backyard bed, a raised box, or a pot on a bright sill, and it asks for very little.
The types run from open rosettes of loose leaves to tight upright romaines and soft, folded butterheads. Loose-leaf kinds let you pick a few outer leaves at a time and keep coming back, while heading types fill out into a single harvest. Whichever you choose, the plant stays small, rarely topping 12 inches (30 cm), so a little space goes a long way.
The one thing lettuce won't forgive is heat. Push it into a hot, dry summer and it shoots up a flower stalk and turns bitter overnight. Give it cool weather, steady moisture, and good light, and the leaves stay sweet and crisp right up to the moment you cut them.
Care
The short version: full sun to a little afternoon shade in the heat, soil kept evenly moist, rich and well-drained ground around a pH of 6.0 to 6.7, and cool weather between 55°F and 64°F (13°C to 18°C) so the leaves never turn bitter.
Light
Lettuce likes full sun in cool weather, but it tolerates partial shade and even welcomes it once temperatures climb. A spot with morning sun and afternoon shade keeps the leaves tender and slows the rush to bolt.
Water
Keep the soil evenly moist at all times, watering every 2 to 3 days and deeper in the heat. The roots sit shallow, so a dry spell stresses the plant fast and turns the leaves bitter. Water deeply to about 6 inches and never let the bed dry out.
Soil
Plant in loamy, rich, well-drained ground with plenty of organic matter worked in. A pH between 6.0 and 6.7 suits it, and soil that holds moisture without staying soggy gives the steadiest growth.
Temperature
This is a cool-season crop that thrives between 55°F and 64°F (13°C to 18°C). Push past about 75°F and it bolts, so time your sowings for the mild shoulders of the year.
Humidity
Ordinary outdoor humidity is plenty, so there's no number to chase. Steady soil moisture matters far more than the air, since dry roots are what turn the leaves bitter.
Feeding
Work in a 5-10-10 fertilizer before planting, then sidedress once with calcium nitrate as the plants grow. That second feed pushes leafy growth and helps head off the calcium shortfall behind tipburn.
Pruning
No real pruning is needed. Pick the outer leaves as you go and the plant keeps producing, then pull it once it bolts, because the leaves only turn bitter from there.
Size & spacing
Lettuce stays compact at 6 to 12 inches (15 to 30 cm) tall and about as wide. Give each plant 6 to 12 inches (15 to 30 cm) of room so the leaves can fill out and air moves freely between them.
When to plant
Lettuce is built for the cool ends of the year, not high summer. Sow the first round in early spring as soon as the soil can be worked, sow again in late summer for a fall crop, and skip the hottest weeks in between when the plants only want to bolt.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 4-6 weeks before the last spring frost
- Plant: 2-4 weeks before the last spring frost; sow again in late summer for a fall crop
- Harvest: Spring and fall harvest (cool season)
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most lettuce trouble shows up on the leaves, and almost all of it traces back to heat, uneven water, or a hungry pest. Catch the early signs and a quick fix usually saves the crop. Match what you see below, then act before the whole planting turns.
A tall stalk shoots up and the leaves turn bitter
This is bolting, the plant's switch from leaf to seed once heat above 75°F (24°C) and lengthening days tell it the season is ending. The leaves bleed a milky sap and lose their sweetness for good. Harvest the moment you see the center rise, give the plants afternoon shade in a hot spell, and lean on slow-to-bolt varieties.
Fix:
- Harvest promptly before the plant fully bolts
- Switch to heat-tolerant, bolt-resistant cultivars
- Provide afternoon shade during hot spells
Curled leaves with a sticky film underneath
Aphids are at work, tiny soft-bodied insects that cluster on the undersides of leaves and leave a sticky honeydew behind. They distort new growth as they feed. Blast them off with a hard jet of water, follow up with insecticidal soap if they hang on, and let ladybugs and other predators do the rest.
Fix:
- Dislodge with a strong spray of water
- Apply insecticidal soap
Brown, scorched edges on the inner leaves
This is tipburn, and it comes from a calcium shortfall inside the fast-growing heart rather than from any pest. When the plant races ahead in warm weather and water swings, the inner leaves can't pull in enough calcium and their edges die back. Keep the soil evenly moist and go easy on nitrogen so growth never outruns what the roots can supply.
Fix:
- Maintain even soil moisture
- Avoid excessive nitrogen that pushes rapid growth
Ragged holes in the leaves with shiny slime trails
Slugs and snails chew these holes after dark and give themselves away with glistening mucus trails, worst in damp weather. Scatter iron phosphate bait, hand-pick them by torchlight, and clear away the moist mulch and debris they shelter in. Watering in the morning leaves the bed dry by nightfall, which they hate.
Fix:
- Apply iron phosphate bait
- Hand-pick at night
- Reduce damp mulch and debris near plants
Toxicity
Lettuce is one of the safest plants you can grow. Every part is non-toxic to people and to cats, dogs, rabbits, horses, livestock, and birds alike, which is why it shows up in so many bowls and hutches. The only quirk is the milky sap, which can leave a mild rash on very sensitive skin and nothing worse.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Lettuce is safe for cats, and a nibbled leaf will do no harm. Most cats ignore it anyway, but a curious one can chew freely.
Dogs None
Dogs can eat lettuce without trouble. A big helping might loosen the stool a little, so plain washed leaves in small amounts are the way to go.
Horses None
Horses handle lettuce well as an occasional treat. Tear it into pieces and keep portions modest, the same as any fresh green.
Rabbits None
Rabbits relish the crisp darker leaves, which suit them far better than the pale, watery hearts. Offer it washed and alongside their usual hay.
Livestock None
Goats, sheep, and backyard stock can graze lettuce safely. Bolted plants going to seed are fine too, just less appetizing once bitter.
Birds None
Chickens and pet birds peck happily at fresh lettuce leaves with no risk. The darker, leafier types give them more to enjoy than the watery crispheads.
People None
Lettuce is a salad staple eaten raw or cooked and is safe for everyone. The milky sap may rarely leave a mild rash on very sensitive skin, nothing more.
The milky sap may rarely cause mild contact dermatitis in sensitive individuals.
Varieties
Hundreds of lettuces exist across the leaf, romaine, and butterhead camps, but a few earn their place season after season. These are the ones worth knowing by name.
Parris Island Cos
A classic upright romaine with tall, crisp green leaves and good resistance to disease.
Tom Thumb
A miniature butterhead that forms a tidy single-serving head in about 70 days.
Simpson Elite
A fast-growing green leaf type that holds out against bolting longer than most.
Red Sails
A bronze-red loose-leaf variety prized for its color and slow march to bolting.
Defender
A romaine bred to shrug off downy mildew and other common diseases.
How to propagate
Lettuce is about as simple as growing gets, and a single packet of seed keeps a salad bed running for months if you sow it in waves.
SeedEasy
Spring and late summer; sow in succession every 2-3 weeks for a continuous harvest · 7-14 days to germinate
Lettuce starts easily from seed, whether you scatter it straight into the bed or raise transplants indoors. Sow it shallow, about a quarter inch deep, since the seed needs light and cool soil to wake up, and it sprouts in 7 to 14 days. Sow a fresh pinch every 2 to 3 weeks through spring and again in late summer, and you'll cut salads for months instead of all at once.
Myths
Bitter lettuce is spoiled or rotten.
Bitterness is the plant's normal answer to heat as it bolts, not a sign of rot. The leaves are still safe, just unpleasant to eat. Keep the crop cool and pick it early and the leaves stay sweet.
Lettuce needs full hot sun all day to grow well.
It's a cool-season crop, and blazing all-day sun pushes it to bolt. A little afternoon shade in the heat keeps it tender, though it still wants plenty of light the rest of the day.