Does lettuce require full sunlight?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Lettuce grows well with 4-6 hours of morning sun but not with too much in the afternoon. Prolonged exposure to direct sunlight will result in bolting, and the leaves will become bitter. When crops hit temperatures over 75°F (24°C), I sometimes use shade cloth to protect summer crops. It is beneficial to expose the plants to gentle morning light and shelter them from strong midday light. This balance preserves texture and effectively extends the harvest window by a considerable amount.
Seasonal Adjustments
- Spring: Maximize sun exposure with 6+ hours during cool weather
- Summer: Provide afternoon shade using 40% shade cloth
- Fall: Return to full sun as temperatures cool below 70°F (21°C)
- Winter: South-facing locations for maximum light absorption
Variety-Specific Needs
- Looseleaf types: Tolerate partial shade better than heading varieties
- Romaine: Requires consistent light but benefits from filtered afternoon sun
- Butterhead: Needs protection from intense light to prevent leaf scorch
- Crisphead: Demands stable light conditions without sudden changes
Use 40% aluminet shade cloth set 12 inches above plants for good shade. This will lower the temperature by 10-15°F, while providing diffused light. Move container gardens in the afternoon to east-facing locations, or under dappled tree shade. These options help avoid heat stress and prevent productivity loss.
Keep a look out for the sun stress indicators on the plants themselves: curled edges of leaves, areas of bleaching, or rapid upward growth. These are signs that your plants require shade RIGHT NOW! Water deeply before 10am so that root zone can cool benefits and evaporative loss is minimized. Moisture in the soil also acts as a thermal buffer against strong sunlight.All of these practices work best together.
Regulate light exposure according to your respective climate. A garden in the south will require significantly more shade than a garden in the north. Coastal climate areas will be naturally fog-bound, while desert climates need the most assistance. Record daily light patterns with basic sun calendars. Your records will indicate the optimal timing for deploying shade.
Read the full article: When to Plant Lettuce: Ultimate Growing Guide
