Lettuce is one of the easiest crops you can grow in your garden. That holds true whether you love full lettuce heads or baby lettuce leaves. Even if you garden in containers, you can have a bumper crop of leafy greens. Follow these tips on how to grow lettuce and leafy harvests and homegrown salads will be on your table soon enough.
When spring arrives, lettuce is one of the earliest crops you can plant outdoors. As soon as your soil is ready to be worked, lettuce seeds are good to go. Lettuce comes in many varieties, from head-forming butterheads to leaf lettuces that never form heads. You can even buy premixed seed packets that include colors from green to purple-red and textures from smooth and soft to crisp and heavily ruffled. Lettuce seeds can germinate with soil temperatures of just 40 degrees Fahrenheit — not far above freezing. But lettuce plants grow best when air temperatures reach 60°F to 65°F.1 Like cabbage and other cool-loving vegetables, lettuce flourishes in cool spring weather, then lets you do it all again come fall. There are even lettuce varieties that tolerate more heat, but most lettuces grow tough, dry and bitter in summer heat. Head-forming lettuces like romaine and butterhead take longer to grow and harvest than leafy lettuces. Spring is a race for heads to mature before temperatures rise too high. Many gardeners start their head lettuce seeds indoors to extend their growing season. Some garden centers offer small seedlings called transplants that accomplish the same goal. In contrast to head-forming lettuces, leafy types are much easier: Seed them straight into spring garden soil.
Lettuce is a cool-weather crop that can be grown in spring and fall in most climates. Starting lettuce from seed indoors and transplanting seedlings outside is a great way to get a head start on the growing season. But when is the right time to transplant those lettuce seedlings into the garden? This complete guide will walk you through the process of when and how to transplant lettuce seedlings for a successful crop.
How Long Should Lettuce Seedlings Grow Before Transplanting?
Lettuce seedlings typically need 4-6 weeks of growth after germination before they are ready to be transplanted outside. The seedlings should have at least 2 sets of true leaves and be 2-3 inches tall before transplanting. Trying to transplant the seedlings too early can shock them and stunt their growth.
Leaf lettuce varieties tend to grow a little faster than head lettuce varieties But for any type of lettuce, the most important indicators of transplant readiness are size and leaf development rather than age. Focus on the height and number of true leaves instead of weeks after germination
Ideal Size for Transplanting Lettuce
- At least 2 sets of true leaves
- 2-3 inches tall
- Well-developed root system
You want the lettuce seedlings to have an established root system before transplanting. This gives them the best chance to resume active growth quickly after being moved to the garden. Leggy overgrown lettuce seedlings may need to be planted a little deeper to re-establish the root system.
When to Start Lettuce Seeds Indoors
Lettuce seedlings grow slowly at first, so start seeds indoors 4-8 weeks before your last expected frost date This gives time for the seeds to germinate and the seedlings to grow big enough to transplant on schedule
Stagger planting lettuce seeds every 2 weeks for a continuous harvest. The timing will depend on your climate:
- In warmer climates, start seeds 6-8 weeks before last frost
- In cooler climates, start seeds 4-6 weeks before last frost
The Earliest Time to Transplant Lettuce Outside
Lettuce seedlings can be transplanted outside as soon as 3-4 weeks before your expected last spring frost date. While lettuce can tolerate light frosts, transplanting earlier than this increases the risk of cold damage.
Some gardeners wait until after the last frost to transplant lettuce as an extra safety margin. But transplanting a few weeks beforehand works well if you harden off the seedlings properly and protect them as needed.
Hardening Off Lettuce Seedlings
Hardening off is the process of gradually acclimating seedlings to outdoor conditions before transplanting. This toughens up the tender plants and helps them withstand transplant shock.
To harden off lettuce seedlings:
- Start 7-10 days before transplanting
- Move seedlings outdoors for just 1-2 hours on the first day
- Slowly increase outdoor time over the course of a week
- Bring seedlings back inside at night
- Leave seedlings outside overnight for the last 2-3 days
How to Transplant Lettuce Seedlings Outside
On transplant day, thoroughly water lettuce seedlings to make removal easier. Carefully dig up each seedling with roots intact. Prepare garden beds by amending soil and creating planting holes. Place each lettuce seedling into its hole, backfill with soil, firm gently, and water well.
Key transplanting tips:
- Handle seedlings by leaves, not stems
- Transplant on a cloudy day or late afternoon
- Water transplants regularly the first week
- Provide shade if hot & sunny after transplanting
- Watch for pests like slugs and cutworms
Lettuce Transplant Spacing
Proper spacing of lettuce plants prevents overcrowding and allows good air circulation. Distance between plants depends on variety:
- Head lettuce – 10-12 inches apart
- Looseleaf lettuce – 4-6 inches apart
- Baby lettuce – 2-3 inches apart
For rows of lettuce, allow 12-18 inches between rows. You can always harvest every other lettuce plant early as “baby” lettuce to thin out the spacing.
Growing Lettuce Transplants Under Lights
Growing lettuce seedlings indoors under LED grow lights allows you to control conditions for optimal growth. Use a seed starting mix in trays or pots. Lightly cover lettuce seeds and keep moist.
Once sprouted, move to 2-3 inches below the lights. Maintain temperatures of 60-70°F and humidity around 70%. Grow lights should be on 16-18 hours per day. Fertilize lightly with diluted liquid fertilizer once true leaves form.
Protecting Lettuce Seedlings Outside
Young lettuce transplants need some special care once moved to the garden:
- Add floating row cover to protect from cold winds
- Use cloches, cold frames, or mini-tunnels if cold overnight
- Provide shade cloth if temperatures exceed 75°F
- Mist leaves daily for the first week after transplanting
- Be diligent about weeds, pests, and diseases
With proper care, lettuce transplants will establish quickly and start growing fast. You’ll be harvesting homegrown lettuce before you know it!
Common Problems When Transplanting Lettuce
Lettuce seedlings are prone to bolting, tipburn, and rotting if conditions after transplanting aren’t right. Here are some troubleshooting tips:
Bolting – Premature flowering. Caused by overmaturity, heat stress, or transplant shock. Start new seeds every 2-3 weeks to stagger harvest.
Tipburn – Browning leaf margins. Usually caused by inconsistent watering. Water thoroughly and evenly.
Damping off – Seedling collapse from fungal disease. Avoid overwatering and increase airflow.
Leggy growth – Spindly, weak seedlings from insufficient light. Use grow lights or start new seeds.
Slow growth – Stunted plants fail to grow after transplant. Harden off better or wait to transplant larger seedlings.
With careful timing, preparation, and aftercare, you can avoid most issues and have great success growing lettuce from seed to harvest. Just remember not to rush – patience is key when it comes to lettuce!
HOW TO PLANT AND TRANSPLANT LETTUCE
Lettuce is one of the few vegetables that tolerates a bit of shade. A planting site with full sun and late-afternoon shade is ideal — especially as summer nears. Well-drained soil with rich organic matter provides the perfect foundation for all lettuce types. Before you plant, mix organic compost and a balanced fertilizer such as Pennington Rejuvenate Plant Food All-Purpose 4-4-4 into your soil. Lettuce grows best when soil pH is between 6.0 and 7.0, the range where most plants thrive.
Lettuce transplants are garden-ready when theyre three to four weeks old. Gradually acclimate transplants to the outdoors before you plant. Transplant head types such as romaine, iceberg and butterhead at 10- to 12-inch intervals, in rows 15 to 18 inches apart. If youre planting in pots or in mixed gardens, allow similar space. For leaf lettuces, sow seed into garden soil. Plant four to six lettuce seeds per inch, in rows at least 2 inches apart. Many gardeners plant swaths of lettuces a foot wide — just keep widths manageable for harvesting. Lightly cover lettuce seeds with 1/8 inch of soil and press gently to ensure good seed-to-soil contact. Depending on the variety, most lettuces mature between 30 and 60 days after planting. Your seed packet will specify whats normal for the lettuces you choose. Plant fall lettuce four to eight weeks before your areas first expected fall frost. For near-continuous spring and fall lettuce crops, plant seeds in succession plantings every two to three weeks.
Head-forming lettuces take longer for harvest than loose-leaf types.
How to Transplant Lettuce Seedlings for HUGE Results
FAQ
Should you transplant lettuce seedlings?
There are 2 main ways to plant lettuce: 1) transplanting seedlings and 2) direct seeding. I do both, depending on my lettuce goals. If I want full-sized heads I prefer to transplant 4 week old seedlings. For baby greens I direct seed.
What cannot be planted next to lettuce?
Try to avoid growing lettuce next to broccoli, brussels sprouts, cabbage, cauliflower, kale, or kohlrabi—while some varieties of lettuce may help these …Jun 7, 2021
How big should seedlings be before transplanting?
Seedlings should generally be around 2-4 inches tall with at least two sets of true leaves before transplanting.