How to Grow Lettuce in Canada: Complete Guide

Why Grow Lettuce in Canada?

Lettuce is one of the easiest and most productive crops for Canadian gardens. It thrives in cool weather, which means our spring and fall shoulders -- the seasons that challenge warm-weather crops -- are exactly when lettuce performs best. A well-planned lettuce patch can supply salad greens from early May through late October in most parts of the country.

Unlike store-bought lettuce that has often travelled thousands of kilometres, homegrown lettuce is crisp, flavourful, and nutrient-dense. You can grow varieties you will never find in a grocery store -- red oakleaf, speckled butterhead, frilly lollo rossa -- turning every salad into something special.

When to Plant Lettuce

Lettuce is cold-tolerant and can handle light frost. This makes it one of the first crops you can plant in spring and one of the last producing in fall.

Spring planting:

• British Columbia (coastal): Direct sow outdoors as early as mid-March
• Southern Ontario (Zones 5-6): Direct sow or transplant mid to late April
• Prairies (Zones 3-4): Direct sow or transplant early to mid-May
• Quebec and Maritimes (Zones 4-5): Direct sow or transplant late April to early May

Fall planting: Sow a second round 8 to 10 weeks before your average first fall frost date. Lettuce planted in late July or August will produce well into October, especially under row cover.

Refer to our frost date tool for precise dates in your area.

Starting Seeds vs Direct Sowing

Lettuce works well both ways, and the best Canadian gardeners do both throughout the season.

Direct sowing is the simplest approach. Scatter seeds thinly and cover with no more than 6 mm (1/4 inch) of fine soil. Lettuce seeds need some light to germinate, so do not bury them deeply. Seeds germinate in 4 to 10 days when soil temperature is 10 to 20 C (50 to 68 F). Note that lettuce seeds go dormant in soil above 25 C (77 F), which is why midsummer sowings often fail.

Indoor seed starting gives you a head start of 3 to 4 weeks. Use 128-cell flats for leaf lettuce or 72-cell flats for head types. Transplant seedlings outdoors when they have 3 to 4 true leaves. This method is especially useful for the first spring planting and for maintaining a continuous harvest through succession planting.

Succession planting is the key to a steady lettuce supply. Sow a new batch every 2 to 3 weeks from early spring until midsummer, then resume in late summer for fall harvests.

Spacing in 30-Inch Beds

Lettuce is a high-density crop in biointensive beds. Multiple rows across the bed maximize your harvest from a small area.

With 4 rows and 8-inch in-row spacing, you get about 6 plants per bed foot (1.5 per row per foot). A 12-foot bed holds roughly 72 lettuce plants. That is a tremendous amount of salad from a small space. For baby leaf lettuce harvested young, you can sow even more densely and cut leaves when they reach 10 to 15 cm (4 to 6 inches).

Growing Tips

Soil. Lettuce has shallow roots and prefers loose, moisture-retentive soil rich in organic matter. Work in compost before planting. A pH of 6.0 to 7.0 is ideal.

Watering. Keep soil consistently moist but not waterlogged. Lettuce wilts quickly in dry conditions and becomes bitter. Water in the morning so foliage dries before evening, reducing the risk of fungal diseases. Drip irrigation is ideal.

Preventing bolting. Bolting (going to seed) is triggered by heat, long days, and drought stress. To delay bolting in summer: choose bolt-resistant varieties, provide afternoon shade using taller crops or shade cloth, keep soil moist, and mulch to keep roots cool.

Recommended varieties for Canadian gardens:

• Leaf: Black Seeded Simpson, Red Sails, Salad Bowl, Tango
• Butterhead: Buttercrunch, Skyphos, Mirlo
• Romaine: Jericho (heat tolerant), Parris Island Cos, Winter Density (cold hardy)
• Oakleaf: Red Oak, Garrison

Available from West Coast Seeds, William Dam Seeds, Halifax Seed, and Vesey's.

Harvesting

Cut-and-come-again: For leaf lettuce, harvest outer leaves when they reach 10 to 15 cm (4 to 6 inches), leaving the growing centre intact. The plant will continue producing new leaves for weeks.

Full head harvest: For butterhead and romaine, wait until the head feels firm when gently squeezed. Cut at the base with a sharp knife. Some varieties will regrow a smaller second head if you leave 2 to 3 cm of stem above the soil.

Harvest in the cool of the morning for the crispest leaves. Immediately plunge harvested lettuce into cold water to remove field heat, then spin dry and refrigerate.

Storage: Washed and dried lettuce keeps in the refrigerator for 5 to 7 days in a sealed container with a paper towel to absorb excess moisture.

Common Problems

Slugs. The number one lettuce pest in Canadian gardens. They feed at night, leaving ragged holes in leaves. Use beer traps, copper tape around beds, or iron phosphate slug bait (safe for organic gardens). Watering in the morning rather than evening reduces slug-friendly dampness overnight.

Aphids. Small insects that cluster on leaf undersides and in the folds of heading lettuce. Blast them off with water, use insecticidal soap, or encourage ladybugs. Severe infestations can stunt growth and make heads unmarketable.

Tip burn. Brown, papery edges on inner leaves of heading lettuce. Caused by calcium deficiency related to irregular watering, not a lack of calcium in the soil. Maintain consistent moisture and avoid letting beds dry out between waterings.

Plan Your Lettuce Beds

Our free garden calculator will help you map out succession planting dates for continuous lettuce harvests throughout the season. For tips on bed setup, seed starting schedules, and crop rotation, visit our getting started guide.