How to Succession-Sow Lettuce

Succession sowing means planting a small number of seeds at regular intervals so you always have edible greens maturing at different times. For lettuce, a practical cadence is every 10 to 14 days during the main growing season; in cool weather you can stretch intervals to 3 weeks, and in warm weather shorten to 7 days for tender baby leaves. Use fast-maturing varieties for baby leaf harvest and slower-heading varieties when you want full heads.

Seed depth and soil matter more than most people expect. Sow lettuce seed 1/8 inch (about 3 mm) deep on a loose, well-draining mix with 50 percent compost or aged manure mixed into top 6 inches (15 cm). A soil pH between 6.0 and 7.0 is ideal. If you are using pots, pick a container at least 6 inches deep for leaf mixes and 8 to 10 inches deep for heading lettuce, with a diameter of 8 to 12 inches for a single head.

Spacing depends on your harvest plan. For continuous baby leaves, broadcast seeds to achieve a final density of about 20 to 30 plants per square foot and harvest when leaves reach 2 to 4 inches. For mature heads, sow seeds 1 inch apart in rows 8 to 12 inches (20–30 cm) apart, then thin to 8 to 10 inches (20–25 cm) between plants once true leaves appear. Record when you sow each batch so you can plan thinning and harvest dates.

Start with a simple calendar: sow Batch A on day 0, Batch B on day 14, Batch C on day 28, and continue. Expect baby-leaf harvests from each batch at 21 to 30 days after sowing, and full heads at 45 to 75 days depending on variety. Label each tray or row with the sow date and variety so you can track which batches to thin or harvest. If you want harvest windows every week, stagger sowing to a 7-day cadence for baby leaves only.

Sowing technique: fill your seed tray or bed with moistened mix, smooth the surface, sprinkle seeds evenly, and press them gently into the soil. Cover very lightly with sifted compost or vermiculite—no more than 1/8 inch. Water with a fine mist so you do not displace seeds. Keep the first tray shaded from hot afternoon sun and aim for soil temperatures between 50°F and 70°F (10°C–21°C) for best germination.

Thinning and harvest: thin seedlings when they have 2 true leaves—usually 7 to 14 days after germination. For baby leaves, you can harvest by cutting outer leaves when they reach 2 to 4 inches long; this yields continuous growth for 2 to 3 cuttings from a single sowing if you harvest selectively. For full heads, remove weaker plants to leave 8 to 10 inches between remaining plants and harvest when heads are firm, typically 6 to 10 weeks after sowing depending on variety and temperature.

Watering and feeding: give lettuce about 1 inch (25 mm) of water per week, more in hot weather or shallow containers. Use a watering method that wets only the root zone—soaker hose or bottom watering reduces leaf wetness and disease risk. Apply a balanced fertilizer such as 5-10-5 at half strength every 3 weeks for container plants; in beds, a light side dressing of compost 2 inches deep along rows every 4 to 6 weeks is sufficient.

Light and temperature control: lettuce tolerates partial shade and prefers 4 to 8 hours of sun. In hot regions, provide afternoon shade or grow in east-facing beds to avoid bolting. Bolting usually occurs when temperatures are consistently above 75°F (24°C); to delay bolting by about 1 to 2 weeks, keep plants evenly watered and provide shade cloth that reduces full sun by 30 to 50 percent.

Pests and simple remedies: slugs and snails are common—use a shallow beer trap or copper barriers and remove them at night. Aphids can be sprayed off with a 10:1 water-to-soap solution or controlled with a steady 2-week program of hand removal and encouraging predatory insects. Rotate your sowing locations by at least 2 feet and use fresh potting mix every season to reduce soil-borne diseases.

Container specifics: for mixed-leaf trays, use a 6-inch depth with drainage holes and aim for 20 to 30 plants per 1 square foot. For a single head in a pot, choose 10 to 12 inch diameter with 8 to 10 inch depth and plant one seed cluster per container. When transplanting seedlings, harden off for 4 to 7 days by gradually increasing outdoor exposure to avoid shock.

Further reading: How to Grow Tomato Plants in Containers · How to Grow Vegetables You Can Harvest in a Month or Less
Sources: UMN Extension