Heat tolerance in lettuce indicates proven enhanced tolerance to tipburn and bolting under heat stress (day and night), while still maintaining the desired head shape. Faster speed of growth is another trait that comes with many heat-tolerant lettuces. Regardless of the variety, even the most heat tolerant lettuce varieties may not be able to handle extreme heat; cultural methods must be utilized to produce a healthy lettuce crop in the heat. Note: we have selected the varieties here in reference to heat experienced during the "summer" growing slot (day/night heat). For some varieties (especially those with closed heads) this will not translate to "spring/fall" (cool-to-hot or hot-to-cool transition). For more recommendations on lettuce planting slots, see our Lettuce Succession Planting Program.
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Truchas
Organic Pelleted Lettuce Seed
Compact, filled-out mini heads that are dark red even in the North.
Salanova® Hydroponic Green Sweet Crisp
Pelleted Lettuce Seed
High-yielding, crispy green leaf with excellent shelf-life.
New Red Fire
Organic Lettuce Seed
Uniform red leaf with heat tolerance and heavy heads of frilly leaves.
Breen
Organic Pelleted Lettuce Seed
Early producer of truly compact mini heads with bronze-red color.
Red Cross
Organic Pelleted Lettuce Seed
Large and fancy, heat tolerant red butterhead for stunning display.