Leaf Lettuce: A Fresh Staple for Every Garden

Plant Characteristics

Leaf and heading lettuce differ in their growth habits. Rather than making heads, it forms loose-leaf rosettes.

• Lifecycle: Grows as an annual (but will bolt and produce seed in hot weather).
• Colors: It varies from light green to dark red and even to variegated leaves.
• Leaf Shape: Crinkled, ruffled, lobed or smooth depending on cultivar.
• Height: Typically 6–12 inches (15–30 cm).
• Growth Habit: Loose, leafy clusters with shallow root systems.
• Flavor: Mild, crunchy, and a little sweet. The red variety can have a touch of bitterness.

Uses

Leaf lettuce can be found in both the garden and at the dinner table.

• Culinary Staple: Fresh in salads, wraps, sandwiches, and garnishes. It is rarely cooked, as high heat causes the leaves to wilt quickly.
• Baby Greens: These are young leaves for a tender, nutrient-dense salad mix.
• Succession Planting: Succession planting is planting something that matures quickly so you can get a lot of harvests during the growing season.
• Ornamental Value: Certain varieties, the red and frilly types in particular look good in edible landscapes.
• Nutritional Benefits: The plants contain dietary fiber, low calories, vitamins and antioxidants that boost the immune system and are beneficial to bones.

Growing Conditions

Leaf lettuce is versatile but does best in the following situations.

• Soil: Best in fertile, well-drained soil high in organic matter with a pH of 6.0-7.0. Choose a high-quality soil mix from our Garden Soil & Potting Mixes selection.
• Watering: Requires consistent moisture. It has shallow roots, which means it dries out quickly, so people need to water it often. Mulching helps retain soil moisture.
• Light: Best in full sun (6+ hours daily), but will tolerate partial shade, especially in hot climates.
• Temperature: The target growing temperature is between 55-70°F (13-21°C). Higher temperatures cause the plant to bolt (shoot up a hastily formed flower stalk) and it produces bitter leaves. Using a Digital Temperature and Humidity Sensor Indoor Series 1000 can help you monitor conditions for optimal growth
• Spacing: Plant thin seedlings with a spacing of about 4 to 6 inches (10 to 15 cm).

Seed Morphology

The lettuce seed is small yet distinct compared to other seeds.

• Size: Between 2 and 3 mm long and very lightweight.
• Color: Usually tan, brown, or grey.
• Shape: Long, thin, flattened and slightly curved at one end.
• Surface: Smooth, which can aid in sowing fast or managing the seeds.

Germination Requirements

Under suitable conditions, lettuce seeds are fairly easy to germinate.

• Temperature: Seed germinates best at 60–70°F (15–21°C). Seeds will face difficulty germinating in soil that is more than 80°F (27°C).
• Light: Lettuce seeds are light-loving; they germinate more easily when planted near the surface of the ground and not very deep.
• Watering: Water should be kept regularly wet and never saturated when germinating.
• Soil Depth: Seeds should be planted ⅛–¼ inch (3–6 mm) in soil, gently pressing them with a fine cover of soil.
• Timeframe: Seeds typically germinate within 7 to 10 days.

Seed Viability and Vigor

Lettuce seeds are quite stable but need excellent storage conditions to keep their germination power.

• Germination Rate: Seeds are generally quite fresh, with a germination rate of 80–90%.
• Viability Period: Seeds are viable for 2–3 years if stored in a cool, dry location.

Vigor Testing: Gardeners can test seed lots by pre-sprouting a few seeds on a moist paper towel 2 to 4 days before planting.

Propagation and Sowing

Leaf lettuce is only grown from seed.

• Direct Sowing: Best sown in the garden as lettuce doesn’t transplant well when it is large. Sow immediately as the ground can be worked in early spring.
• Indoor Sowing: Seeds can be started indoors 3-4 weeks before the last frost and transplanted gently when young.
• Succession Planting: Sow fresh seed every 2 to 3 weeks for a continual supply all season long.
• Spacing: For baby greens, plant closely when plants are full size, thin seedlings to stand 4–6 inches apart. Row: 12–18 inches apart.
• Harvesting: Start picking outer leaves when 4–6 inches tall, or pick whole heads at full size.

Disease and Pest Resistance

Leaf lettuce is fairly low maintenance, but it is susceptible to a few common problems.

• Aphids: These insects feed on leaves, making them curl and spread diseases. Infestations can be controlled with neem oil or insecticidal soap, by using Seabright Laboratories Aphid/Whitefly Traps, 5 pack to catch and monitor pests.
• Slugs and Snails: A pest that is especially harmful to young plants. Copper tape, diatomaceous earth or hand-picking may prevent damage.
• Downy Mildew: A fungal disease that results in yellow spots on foliage. Do not water from overhead and allow for adequate air circulation.
• Lettuce Mosaic Virus: This virus, often spread by aphids, causes mottled leaves and stunted growth. Use resistant cultivars when possible.
• Bolting: Not a pest or disease, but bolting (early flowering) reduces leaf quality. Shade cloths and sowing at the right time can prevent this.

Storage and Handling

Store it properly to keep leaf lettuce fresh and seed viability.

• Harvest Handling: Harvest in the morning, the leaves are then the crispest. Don’t wash until ready to use them, so as not to spoil them.
• Refrigeration: Fresh leaves can be kept in a plastic bag or container in the refrigerator for 7–10 days.
• Seed Storage: Seeds should be stored in a cool, dark, dry place and used within a year.
• Shelf Life of Seeds: Properly conserved, seeds remain viable for 3 years.

Summary

Leaf lettuce is an easy and rewarding crop for most gardens. Its open, tender leaves are fast and easy to harvest, and its versatility allows it to be grown in small pots and large garden beds. People will be able to make fresh salads, sandwiches, and wraps with minimal effort directly out of their backyard.