Romaine lettuce is a popular leafy green veggie that is a staple ingredient in many salads. As a cool weather crop, romaine lettuce thrives in the spring and fall. With proper care and cultivation, you can grow lush, healthy heads of romaine lettuce right in your own backyard. Read on to learn what romaine lettuce needs to grow its best.
Sun and Temperature Requirements
Romaine is a cool weather crop that prefers temperatures between 60-70°F. It can tolerate temperatures down to 40°F. Once temperatures exceed 75°F, romaine lettuce will start to bolt and become bitter. Romaine grows best with 8-10 hours of full sun per day. Make sure to plant it in a spot that receives sufficient sunlight.
The optimal daytime temperatures for growing romaine lettuce are:
|Stage of Growth
|Ideal Day Temps
Romaine lettuce can tolerate some shade but yields the best results in full sun. Make sure the plants get at least 6-8 hours of direct sunlight per day for optimal growth. Leaf color and flavor will be more intense when grown in full sun.
Romaine lettuce requires nutrient-rich soil with a pH between 6-7. The soil should be loose, well-drained, and rich in organic matter. Adding compost or aged manure helps provide nutrients and enhances drainage. Before planting, till the top 6 inches of soil.
Here are some key soil properties for optimal romaine lettuce growth:
- pH between 6-7
- Loose, crumbly texture
- High organic matter content
If your soil is dense, compacted, or depleted, add organic amendments like compost or peat moss to improve fertility and texture before planting.
Romaine lettuce requires regular water to form crisp, juicy leaves. The soil should be kept moist but not waterlogged. Allow the top 1-2 inches of soil to dry out between waterings.
Here are some tips for proper romaine lettuce watering:
- Water when top inch of soil is dry
- Provide 1-2 inches of water per week
- Use drip irrigation or soaker hoses to keep foliage dry
- Water early in the morning
- Avoid overhead watering
- Maintain even soil moisture
Lettuce leaves can rot easily if soil is kept too wet. Allow soil to dry slightly between waterings and avoid waterlogged conditions.
Romaine lettuce benefits from regular fertilization starting a couple weeks after seedlings emerge. Use a balanced liquid fertilizer or side-dress with compost tea every 2-3 weeks. Avoid over-fertilization which can cause excess foliage growth at the expense of the lettuce heads.
Recommended fertilization schedule:
- 2-3 weeks after seedling emergence
- Repeat every 14-21 days
- Use compost tea or fish emulsion
- Top dress with compost
- Discontinue fertilizing 2 weeks before harvest
The best fertilizers for romaine lettuce provide steady nitrogen as well as essential nutrients like phosphorus, potassium, and calcium. Organic options like compost, fish emulsion, and compost tea work great.
Certain companion plants can benefit romaine lettuce by deterring pests, increasing nutrients, or provide shade coverage. Here are some great companion options:
- Radishes – Repel cucumber beetles
- Garlic – Deters aphids and other pests
- Green onions – Distract carrot flies
- Beets – Provide shade coverage
- Beans – Fix nitrogen in soil
- Carrots – Maximize garden space
Avoid planting romaine lettuce near crops in the cabbage family which are prone to similar pests and diseases.
Days to Maturity
Romaine lettuce typically takes 50-70 days to reach maturity and full size from transplanting seedlings. The days to maturity depends on the lettuce variety. Some types are faster growing while heirloom varieties may take longer.
Here are the general days to maturity for different types of romaine lettuce:
|Days to Maturity
Factor in an additional 2-3 weeks if growing romaine lettuce from seed rather than established seedlings. Romaine lettuce can be harvested as baby greens within 30-45 days for a cut-and-come-again crop.
Proper spacing allows air circulation and prevents overcrowding. For full size heads, space romaine lettuce plants 8-12 inches apart in rows 12-18 inches apart. Baby lettuce can be grown more densely with 4-6 inches between plants.
Recommended spacing for romaine lettuce:
- Full size – 12 inches apart in rows 15 inches apart
- Semi-heads – 8 inches apart in rows 12 inches apart
- Baby leaf – 4-6 inches apart in rows 6-12 inches apart
To maximize space, plant quick growing crops like radishes or spinach between the lettuce rows. Just make sure to leave enough room for the lettuce to reach full size.
Growing From Seed
Starting romaine lettuce from seed is simple. Sow seeds 1⁄4 inch deep in pots or trays 6-8 weeks before your last frost date. Keep the starting mix moist and provide plenty of light. Temperatures between 60-70°F are ideal for germination which takes 7-10 days. Once seedlings have 3-4 true leaves, transplant them outside 12-18 inches apart.
Here are some tips for starting romaine lettuce from seed:
- Sow 1⁄4 inch deep
- Keep soil moist not soggy
- Grow at 60-75°F
- Use full spectrum grow lights
- Thin overcrowded seedlings
- Harden off before transplanting
Starting seeds indoors gives you a head start on the growing season. Just make sure seedlings are properly hardened off before transplanting outdoors.
Growing From Transplants
For faster harvests, start with nursery-grown romaine lettuce transplants. Look for stocky seedlings with 4-6 true leaves. Transplant them 12-18 inches apart into the garden after the last frost. Water transplants after setting them in the ground and provide shade if temperatures rise above 75°F.
Follow these tips when planting romaine transplants:
- Select healthy, green transplants
- Harden off before planting
- Set transplants slightly deeper than growing in tray
- Water thoroughly after transplanting
- Protect from hot sun for 1 week
Getting a jump start with transplants allows you to skip the indoor seed starting. Just take care not to disturb the roots when transplanting.
Romaine lettuce grows well in containers at least 12 inches deep. Use a potting mix formulated for vegetables, with extra perlite or vermiculite added to improve drainage. Fertilize more frequently in containers since they have less nutrients. Place containers in full sun.
Here are some tips for growing romaine in containers:
- Use containers at least 12 inches deep
- Use potting mix for veggies
- Improve drainage with perlite or vermiculite
- Allow 6-12 inches between plants
- Water when soil dries out
- Fertilize every 2-3 weeks
With proper care, you can grow romaine lettuce successfully on a patio, balcony, or any small space. Just make sure the containers have adequate drainage.
Common Pests and Diseases
Romaine lettuce is prone to several pests and diseases. Here are some of the most common issues and how to manage them:
Slugs feed on young seedlings and can decimate lettuce plants overnight. Control with diatomaceous earth or other slug bait products. Remove any boards, stones, or debris that provide hiding spots.
These small sucking insects cluster on young lettuce, distorting leaves and transmitting disease. Knock aphids off with strong blasts of water and spray neem oil or insecticidal soap.
Tiny black flea beetles chew numerous small holes in lettuce leaves. Use floating row covers to exclude the beetles and treat with neem oil if infestation is severe.
This fungal disease causes yellowish spots on upper leaf surfaces. Lower leaves develop white fungal growth. Improve air circulation and avoid wetting foliage. Spray copper fungicide if disease is present.
A bacterial disease that quickly rots the bottom of lettuce heads. Prevent by rotating planting sites and avoiding overhead watering. Clean up crop debris promptly after harvest.
Check lettuce frequently for any signs of pest damage or disease. Address issues promptly to protect plants and avoid spreading problems.
Harvest romaine lettuce once the heads fill out, usually 50-75 days from planting. Cut the heads with a sharp knife 1-2 inches above the soil, in the early morning when crisp. Harvest individual leaves from the outside as needed so the center continues growing.
Follow these romaine lettuce harvesting tips:
- Harvest in the morning when coolest
- Cut lettuce heads 1-2 inches above soil
- Use a sharp knife for clean cuts
- Handle carefully to avoid bruising
- Chill immediately after picking
Romaine can also be grown as a cut-and-come-again crop, harvesting outer leaves when they reach 4-6 inches tall. Leave the center in place and it will continue producing more leaves.
Storing the Harvest
Romaine lettuce will only store for 5-7 days when kept refrigerated. To extend shelf life, wash heads in cool water and dry thoroughly before storing in plastic bags in the fridge. Do not wash lettuce until ready to use.
Tips for storing romaine lettuce:
- Refrigerate immediately at 32-35°F
- Do not wash until ready to use
- Store in plastic bag with dry paper towel
- Use within 5-7 days
- Avoid storing near ethylene producing fruits
For best quality and texture, use harvested romaine within a few days. Outer leaves or individual leaves will store longer than whole heads.
Preserving the Harvest
Romaine lettuce does not preserve well compared to other lettuce varieties. It has high water content and delicate leaves. Here are some possible options for preserving romaine:
- Freezing – Blanch leaves then freeze in airtight bags up to 6 months.
- Dehydrating – Dry at 115°F until brittle and store in airtight containers.
- Canning – Hot pack blanched leaves in glass jars with a salty brine solution.
- Pickling – Pickle leaves or quarters in a brine. Refrigerate up to 3 months.
Freezing and dehydrating are the easiest methods for preserving fresh romaine lettuce to enjoy out of season. Canning works but is more time consuming.
Romaine lettuce provides vitamin C, potassium, and fiber. Here are some of the best ways to enjoy its crunchy leaves:
- Caesar salad
- Salad mixes
- Wraps and sandwiches
- Burgers and tacos
- Juicing and smoothies
- Pickled lettuce stems
The upright leaves and crisp texture of romaine lettuce make it perfect for Caesar salads. It also adds a nice crunch to wraps, burgers, tacos, and more. Get creative with this versatile lettuce!
With its deep green leaves and crisp texture, romaine lettuce is a tasty addition to salads and sandwiches. By providing the right growing conditions, this cool season crop can be easily cultivated in any vegetable garden or container. Romaine thrives with plenty of sun, nutrient-rich soil, even moisture, and cool temperatures. Give it the care it needs and enjoy fresh harvests in your backyard.