Fresh salad greens whenever you want them, no garden required. Lettuce is one of the easiest vegetables to grow indoors - it's fast, compact, and tolerates lower light than most edibles.
This guide covers everything from variety selection to harvest techniques for a continuous supply of homegrown salad.
Why Lettuce Thrives Indoors
Lettuce has several advantages as an indoor crop:
- Shade tolerant - Grows with less light than tomatoes or peppers
- Fast growing - Baby leaves ready in 3-4 weeks
- Compact - Shallow roots suit containers perfectly
- Cool loving - Indoor temperatures are ideal
- Cut-and-come-again - Harvest repeatedly from one planting
Best Lettuce Varieties for Indoors
Loose-Leaf Lettuce
The easiest type to grow indoors. Pick individual leaves as needed while the plant keeps producing. Varieties like 'Salad Bowl', 'Red Sails', and 'Oak Leaf' are reliable performers. Ready to harvest in 4-6 weeks.
Butterhead/Bibb Lettuce
Soft, tender leaves with a mild, sweet flavour. Forms loose heads but can be harvested leaf-by-leaf. 'Buttercrunch' and 'Tom Thumb' are compact varieties perfect for containers.
Romaine Lettuce
Upright growth habit makes good use of vertical space. Can harvest outer leaves or wait for full hearts. Takes slightly longer (6-8 weeks) but worth it for the crunchy texture.
Mesclun Mixes
Blends of baby lettuces and other salad greens. Harvest young at 3-4 weeks for tender, diverse salads. Perfect for cut-and-come-again growing.
Light Requirements
Lettuce is more forgiving than most vegetables, but light still matters:
Natural Light
- Ideal: South-facing window with 10-12 hours of light
- Acceptable: East or west window with 6-8 hours
- Marginal: North-facing - growth will be slow
Grow Lights
In winter or low-light situations, supplemental lighting transforms results. Position lights 15-20cm above plants and run for 12-14 hours daily. LED grow lights are efficient and produce minimal heat.
Container and Soil
Container Size
Lettuce has shallow roots - 15cm depth is sufficient. Wide, shallow containers work better than deep pots. Ensure drainage holes to prevent waterlogging.
Soil Mix
Use quality potting compost mixed with perlite for drainage. Lettuce likes rich soil - add slow-release fertiliser at planting or use compost-enriched mix.
Watering Lettuce
Consistent moisture is the key to crisp, sweet lettuce. Irregular watering causes bitter, tough leaves.
How Much and How Often
- Keep soil consistently moist but not waterlogged
- Check daily in warm conditions, every 2-3 days in cool
- Water when top 2cm of soil feels dry
- Water at soil level to keep leaves dry and prevent disease
Self-watering containers are ideal for lettuce - they provide the steady moisture lettuce craves without the risk of overwatering.
Temperature
Lettuce prefers cool conditions - one reason it does well indoors away from summer heat:
- Ideal: 15-20°C (60-68°F)
- Acceptable: 10-24°C (50-75°F)
- Too hot: Above 24°C triggers bolting
Keep plants away from heat sources like radiators and hot windows. A slightly cool room produces the best lettuce.
Succession Planting
For continuous harvest, don't plant all your seeds at once. Sow small amounts every 2-3 weeks. As one planting matures, the next is coming up behind it.
Sample Schedule
- Week 1: Sow first batch
- Week 3: Sow second batch
- Week 5: Harvest first batch, sow third batch
- Continue the cycle...
Harvesting Techniques
Cut-and-Come-Again
The most productive method for indoor growing. Cut outer leaves when they reach 10-15cm, leaving the centre to continue growing. One plant can provide harvests for 6-8 weeks before it needs replacing.
Baby Leaf Harvest
Cut entire plants when leaves are 5-8cm long, about 3-4 weeks after sowing. Dense sowing works well for this method - scatter seeds thickly and harvest the whole crop young.
Full Head Harvest
For butterhead or romaine, let plants mature fully (6-8 weeks) and cut the entire head at the base. Plants won't regrow after this type of harvest.
Common Problems
Bolting (Going to Seed)
Cause: Heat or stress triggers flowering
Solution: Keep cool, harvest before flowering, grow bolt-resistant varieties
Bitter Taste
Cause: Heat, irregular watering, or harvesting too late
Solution: Maintain consistent moisture, harvest young, keep cool
Leggy, Stretched Growth
Cause: Insufficient light
Solution: Move to brighter location or add grow lights
Tip Burn (Brown Leaf Edges)
Cause: Calcium deficiency or irregular watering
Solution: Maintain even moisture, add calcium if persistent
Aphids
Cause: Common indoor pest
Solution: Blast off with water, use insecticidal soap if needed
Starting from Seed
Lettuce is best grown from seed rather than transplants - it's fast, cheap, and gives you variety choice.
Sowing
- Sprinkle seeds on moist compost surface
- Press lightly but don't bury - lettuce needs light to germinate
- Keep moist with a spray bottle
- Germination: 7-10 days at 15-20°C
Thinning
Once seedlings have 2-3 true leaves, thin to 10-15cm apart for leaf lettuce, 20cm for heading types. Eat the thinnings as microgreens.
Perfect for Growing Lettuce
Garden Stack self-watering planters deliver the consistent moisture lettuce needs for sweet, crisp leaves. No more bitter greens from irregular watering - just fresh salads whenever you want them.
See Garden Stack