Lettuce in a greenhouse is not just a summer crop, with the right choice of varieties you can have fresh leaves 10-11 months a year. The calendar below guides you through all the months and tells you what to plant when.
Winter crops (November, February)
A winter greenhouse does not have to be heated, if you choose frost-resistant varieties, you can harvest lettuce at -2°C outside. The best choices:
- Valerianella, withstands up to -10°C, sow Sep-Oct, harvest Dec-Mar
- Red winter lettuce, slow growth, but very resistant
- "Polar" spinach, sow Aug-Sep for winter harvest
- Wild arugula, survives even under snow
Spring crops (March, May)
Spring is the peak season for lettuce, growth is fast, but beware of late spring frosts. Sow in the greenhouse from mid-February, outdoors up to mid-March:
- Buttercrunch, crunchy heads, sow Feb-Apr
- Lettuce, all season, best in spring
- Endive, bitter taste, maturation 8-10 weeks
- Red radish, slow, but rich in antioxidants
For continuous harvest: sow every 2 weeks in small quantities, not all at once.
Summer crops (June, August)
In the summer, the biggest challenge is heat, at 25°C+ lettuce "goes to seed" (produces seeds, becomes bitter). Solution:
- Heat-resistant varieties: "Sangria", "Lollo Rosso", "Black Seeded Simpson"
- Shading: 30-50% mesh over the greenhouse roof in July-August
- Mulching the soil, straw or paper bag retains moisture
- Watering early in the morning or late in the evening
Autumn crops (September, October)
The second golden season for lettuce. Cooling means faster growth and fewer pests. Ideal varieties for Sep-Oct sowing:
- Endive "Bubikopf"
- Lettuce "Zalim"
- Radicchio "Castelfranco"
- Chinese broccoli
For an extended season, we recommend reading the article Autumn preparation of the greenhouse.
General tips for lettuce crops
Three key tips for success:
"Lettuce has shallow roots. Wet soil is not a problem, but dry soil in heat means immediate decay. Mulching is a must.", gardener Janez K., Maribor
- Rotation: do not plant lettuce in the same place more than 2 years in a row
- Composting: add 3-5 cm of compost before the season
- Group planting: lettuce + radish + carrot = optimal use of soil
With proper planning of varieties, a family of 4 can cover all their lettuce needs from 8 m² of greenhouse.
Start growing lettuce
A smaller greenhouse of 6-12 m² is enough for year-round self-sufficiency in lettuce. Check out our hobby models.
Greenhouses for hobby gardeners