Lettuce

Growing Lettuce in Zone 3b

A complete, zone-3b timeline for Lettuce — when to start, transplant, and harvest, tuned to this zone's typical frost dates (International Falls, MN; Fargo, ND).

May 17Last spring frost
September 23First fall frost
about 129 daysGrowing season
−40 to −30°FWinter low

Your planting timeline

  1. Direct sowonce soil warms, around May 17
  2. Harvestabout 30–70 days from transplant

Best varieties for zone 3b

Lean on fast, cold-hardy loose-leaf types like Black-Seeded Simpson, Red Sails, and Winter Density that mature quickly in the short, cool season.

Growing notes

Lettuce has shallow roots and high water content, so it wants steady, even moisture — roughly 1 to 1.5 inches per week, delivered as light, frequent waterings rather than occasional soakings. Let the bed dry out and growth stalls while the leaves turn tough and bitter and bolting speeds up. Water at the base in the morning so foliage dries quickly, which discourages downy mildew and rot in the dense, tender leaves. A thin mulch of straw conserves moisture and keeps soil cool around the roots. Container and raised-bed lettuce dries fastest and may need watering daily in warm weather. Consistency is everything: erratic wet-then-dry swings produce bitter, stringy leaves.

Recommended supplies

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