Does lettuce need full sunlight to thrive?
Written by
Benjamin Miller
Reviewed by
Prof. Martin Thorne, Ph.D.Light requirements for growing lettuce differ by type and the location's climate and environment. Crisphead types require about 6-8 hours of filtered sunlight each day, while looseleaf types are happy with only 4 hours of morning sunlight. For example, on my shaded fire escape in Brooklyn, I grow a leafy salad mix each week using Oakleaf and Buttercrunch. This shows that flexibility can exist with lettuce.
Sunlight Monitoring
- Use analog light meters for accuracy
- South-facing windows need 50% diffusion
- Rotate pots 90° daily for even exposure
Shade Solutions
- Aluminum foil reflectors boost low light
- Trellis-mounted shade cloth adjusts angle
- Companion plants filter harsh noon rays
Soil conditions enhance the effectiveness of light. I use a mixture of 40% compost and 60% vermiculite, which holds moisture during sunny conditions. To determine drainage, simply time how quickly 1 cup (240ml) of water drains, with the best timing being between 8 and 12 seconds. If it drains too slowly, add some perlite. If it drains too fast, add some coconut coir.
Watering is synced with the intensity of sunlight. I water in the morning to avoid midday evaporation - I set drip lines with timers for 7 AM. If experiencing a heat wave, I add 2-3 ice cubes (alone) at the base of a plant stem (not on the foliage). This will cool the base of the plant and the roots, without shocking the plant itself.
Preventing bolting involves controlling light and nutrients simultaneously. At the very first appearance of the flower stalk, I recommend you apply the kelp tea (1 tablespoon per gallon of water). You may also safely cut back the lower leaves to reorient energy for vegetative growth. My hybrid approach has been shown to delay seed production over shading alone by 18 days.
Read the full article: How to Grow Lettuce: Expert Tips for Every Gardener
