Lettuce

Lettuce (Lactuca sativa) is a cool-season annual that grows faster than almost anything else you can put in a garden and, depending on variety, can be harvested 45 days from seed. It’s also one of the clearer-cut value propositions in a small home garden: packaged salad greens retail for $4.00–$6.00 for 5 oz at most grocery stores (USDA Agricultural Marketing Service, 2023), which puts the per-pound cost in the $12–$20 range. Home-grown lettuce costs a fraction of that, and you’re harvesting it at peak freshness rather than five to ten days after it was cut.

The catch is that lettuce has a short productive window. When air temperatures push above 80°F, the plant bolts - it sends up a seed stalk, leaves turn bitter with elevated lactucarium, and the harvest is over. In most of the continental US, this limits outdoor lettuce to spring and fall seasons, with a gap through peak summer heat.

What you’re choosing between

The four practical categories differ in habit, speed, and best use.

Looseleaf types (Red Leaf, Green Leaf, Oak Leaf) are the fastest to harvest and the most forgiving. They don’t form tight heads, which means you can cut outer leaves and the plant keeps producing. They’re the right choice for cut-and-come-again harvesting and the easiest introduction to growing lettuce.

Butterhead types (Boston, Bibb) form loose, soft heads with a notably sweet, mild flavor. They’re slower than looseleaf - 60–65 days to a full head - but the eating quality is noticeably different.

Romaine forms upright, elongated heads with more structure than butterhead. It tolerates warm temperatures better than most types before bolting, which extends the productive window by a week or two.

Iceberg (crisphead) requires the most days to mature, the most space, and the most consistent cool temperatures to form tight heads. It’s the most demanding type to grow at home and the least cost-effective given what iceberg sells for retail. Grow it if you want to; just understand it’s the hardest category.

The ROI case

A $2.50 seed packet contains far more seeds than one season requires - lettuce seed viability holds for two to three years if stored cool and dry, so leftover seed isn’t waste. At $0.05–$0.10 per plant and multiple cuts from looseleaf varieties, the cost-to-value ratio for lettuce is among the best of any home garden crop. Three to four square feet of well-managed looseleaf lettuce will supply a household with salad greens through a full cool-season growing window.

Growing requirements

Lettuce germinates best with light. Surface-sow or cover seeds with no more than 1/8 inch of soil - light aids germination and deep sowing suppresses it (University of Vermont Extension, Growing Lettuce, 2019). Germination is reliable at soil temperatures of 40–65°F; above 75°F, germination drops sharply due to thermodormancy. If you’re starting seeds in warm weather for a fall planting, germinate them in a cool location or use the refrigerator for 24–48 hours before sowing to break dormancy.

Soil pH of 6.0–7.0 is the acceptable range. Lettuce is a light feeder with a shallow root system - it benefits more from consistent moisture than from heavy fertilization. Amend beds with compost before planting; established plants need little additional feeding unless leaves are pale, in which case a dilute liquid balanced fertilizer addresses nitrogen deficiency quickly.

Thin seedlings to 6–8 inches for looseleaf types and 10–12 inches for head types. The thinnings are worth eating - they’re effectively microgreens at that stage.

Succession planting is the main technique for continuous production. Sow a new small batch every two to three weeks through spring, then again starting six to eight weeks before your first fall frost. This distributes your harvest across the season rather than creating a single flush.

When temperatures start climbing toward 75–80°F, use shade cloth or position lettuce beds where taller plants provide afternoon shade. A few degrees of cooling extends the productive window before bolting by one to three weeks.

Growing windows by zone give you a rough planning target: Zone 4–5 growers get a spring window from roughly 4–6 weeks before last frost through late May or early June, and a fall window starting in early August. Zone 6–7 growers can extend spring harvest into mid-June and push fall planting back to September. Zone 8–9 growers have a longer fall-to-spring window - October through April in Zone 8 with careful variety selection, and nearly the entire mild season in Zone 9. In Zone 9 and warmer, summer is the gap and fall is the main season rather than a secondary one. Romaine tolerates the most heat before bolting; looseleaf types bolt fastest; butterhead falls between the two. This ordering holds regardless of zone.

What goes wrong

Bolting is the primary failure mode. Once a lettuce plant decides to bolt - triggered by long days and high temperatures - you can’t reverse it. Leaves turn bitter quickly. Harvest the remaining leaves immediately and start a new planting. Choose slower-to-bolt (heat-tolerant) varieties like Jericho or Nevada for late spring; they buy time in marginal conditions.

Slugs and snails are the most damaging lettuce pest in most regions. They feed at night, leaving irregular holes in leaves and a slime trail. Iron phosphate bait (slug pellets) is effective and safe around vegetables and pets. Diatomaceous earth around the bed perimeter helps but loses effectiveness when wet.

Downy mildew (Bremia lactucae) appears as pale green or yellow patches on upper leaf surfaces with white sporulation on the undersides, typically during cool, humid weather. Good air circulation between plants and avoiding overhead irrigation in the evening reduces infection pressure. Many commercial looseleaf varieties have resistance to known Bremia races; check catalog descriptions.

Tipburn is a calcium deficiency in inner leaves that shows as brown, papery leaf edges, most common on head types during periods of fast growth. It’s not caused by low soil calcium but by poor internal translocation during rapid expansion. Consistent watering and avoiding overfertilization with nitrogen reduce tipburn incidence (Cornell Cooperative Extension, Lettuce Production, 2021).

Harvest and storage

For looseleaf varieties: cut outer leaves with scissors 1 inch above the crown, leaving the center growing point intact. The plant regrows and you can repeat this three to five times over several weeks. Eventually the quality declines and the plant needs replacing.

For head types: harvest the whole head by cutting at the base when the head feels firm under gentle pressure. Don’t let head types sit too long; overmature heads split and become bitter.

Lettuce deteriorates fast after cutting. Refrigerate unwashed in an airtight bag with a paper towel to absorb moisture. Use within five days. Washing and spinning greens dry before storage extends fridge life to about a week.

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Related crops: Strawberry, Green Bean

Related reading: Spring Garden Planning - timing your cool-season crops around frost dates and soil temperature