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Lettuce Seed Starting Tips

Lettuce seedling

 

Lettuce seedling
Lettuce seedling

Lettuce grows best in the cool weather of spring and fall.

Time lettuce seed sowing so plants come to harvest before very warm and hot weather, Hot weather will trigger bolting and seed-stalk formation. Bolting can be slowed by picking the oldest leaves first but it can’t be stopped. Lettuce that bolts will be bitter flavored, so it is best to harvest lettuce before the weather gets too warm.

There are many types of lettuce to choose from: butterhead or Bibb is loose textured with a loose head; looseleaf has a loose, rosette of leaves; romaine or Cos has an elongated, erect head; crisphead or iceberg has a solid, tightly folded head.

Lettuce matures in 40 to 80 days depending on the type planted: looseleaf in 40 days, butterhead in 40 to 70 days, and romaine and iceberg in 80 days.

Lettuce Sowing and Planting Tips

  • Lettuce is grown from seeds or transplants.
  • Seed is viable for 5 years.
  • Start lettuce indoors 4 weeks before transplanting; sow or transplant lettuce into the garden as soon as the soil can be worked.
  • Seed germinates in 2 to 10 days at or near 70°F (21°C)—but sometimes seed can take up to 2 weeks to germinate if the soil is cold.
  • Keep the soil evenly moist until seeds germinate then keep the soil moist until seedlings are well established.
  • Sow seed ¼ to ½ inch (6-13mm) deep.
  • Sow seeds 4 inches (10cm) apart; later thin seedlings according to type: leaf, 6-9 inches (15-23 cm) apart; head, 10-12 inches (25-30 cm) apart. Make sure there is good air circulation around maturing plants to avoid disease.
  • For intensive planting, space plants 10 inches (25 cm) apart in a staggered pattern.
  • Lettuce grows best in full sun but can tolerate light shade.
  • The optimal growing air temperature for lettuce is 40°-75°F (4-24°C).
  • Lettuce prefers a soil pH between 6.0 and 6.8.
  • Add aged compost to planting beds in advance of sowing; compost will feed the soil and aide moisture retention.
  • Avoid planting lettuce where radicchio, endive, escarole, or artichokes have recently grown.
  • Make successive sowings every few weeks for an extended harvest.
  • Fertilize with an organic fertilizer such as fish emulsion at half strength.
  • Aphids, flea beetle, cutworms, earwigs, leaf miners, snails, and slugs can attack lettuce.

Interplanting: Interplant lettuce with beets, carrots, cucumbers, onions, radishes, and strawberries.

Container Growing: A single head of lettuce does well in a 6 inch (15 cm) pot; in larger containers plant on 10 inches (25 cm) centers.

Lettuce Planting Calendar

  • 10-8 weeks before the last frost in spring: direct-sow in a plastic tunnel or cold frame.
  • 6-4 weeks before the last frost in spring: direct sow in the garden
  • Every 3 weeks sow succession crops for continuous harvest; hot weather will cause bolting.

For Fall Harvest:

  • 8-6 weeks before the first frost in fall: direct-sow or transplant seedlings into the garden.
  • 6-4 weeks before the first frost in fall: sow or transplant in a plastic tunnel or cold frame for fall and winter harvest.
Lettuce in rows
Sow lettuce very 3 weeks for continuous harvest.

Lettuce Recommended Varieties

  • Butterhead type: ‘Bibb’, ‘Buttercrunch’, ‘Migonette’, ‘Boston’, ‘Four Seasons’, ‘Tom Thumb’.
  • Leaf types: ‘Black-Seeded Simpson’. ‘Lolla Rossa’, ‘Black Oak’, ‘Red Sails’, ‘Salad Bowl’, ‘Ruby’.
  • Romaine type: ‘Little Gem’, ‘Parris Island’, ‘Rogue d’Hiver’.
  • Iceberg type: ‘Great Lakes’, ‘Nevada’, ‘Sierra.’

Botanical Name: Latuca sativa

Lettuce belongs to the Compositae (Asteraceae) or sunflower family.

More lettuce growing tips: How to Grow Lettuce.

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6 Comments

  1. This is a great site. Lots of very useful information.
    My father-in-law used to grow a Bibb-type lettuce he called “Half-Century”. He saved the seed from year to year. While cleaning out their house I found some old seed, probably at least 20 years old, and have been trying to recover the strain. So far, I have not had any luck despite treating with gibberellic acid, rooting hormone, sugar, nitrate, cold, and sunlight. Can you or any of your readers offer any suggestions?
    Thanks,

  2. Total newbie and I feel like this question is never clear.. while sowing inside, after you plant seeds in your container, does it need any light to germinate?? I know once it sprouts it does, but there is such conflicting information on this? I tried a couple outside in a covered container since weather is a bit sporadic and some inside on windowsill uncovered?? Please advise.

    • Some seeds will germinate without light above the soil. As a general rule, some light is best and means you don’t have to second guess. Small seeds will germinate with just a bit of soil cover– 1/8 inch. Large seeds usually draw moisture from the soil to help the seed coat dissolve. A good rule of thumb is to plant seeds as deep as they are wide and place them where they get some sunlight until they germinate.

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