Lettuce is the quintessential aeroponic crop. It's fast (21-25 days from seed to harvest), productive (cut-and-come-again for months), and the taste difference versus supermarket lettuce is dramatic. Here's how to grow it perfectly.
Choosing Your Variety
Different lettuce varieties have different characteristics. For Indian home growers, we recommend starting with:
Butterhead (Butter lettuce): Compact, tender, mild flavour. Ideal for small ports. Tolerates slightly warmer temperatures better than other varieties.
Red Oak Leaf: Loose-leaf variety, fast-growing, beautiful deep red colour. Excellent cut-and-come-again performance. Popular in restaurants.
Romaine (Cos): Taller, crispier, holds up better in salads. Takes slightly longer (25-30 days) but produces more per plant.
For your first grow, plant 2-3 varieties to discover what your family prefers.
Germination
Place 1 lettuce seed per starter plug. Soak plugs for 5 minutes, insert seed to 5mm depth. Keep in a warm, dark location (24-28°C). Lettuce germinates in 2-4 days — faster than most seeds.
Once the sprout is 1-2cm tall and you can see the first true leaves forming (the second set of leaves, after the initial seed leaves), it's ready to transplant.
Nutrient Requirements
Lettuce is a light feeder. For seedlings: 400-600 ppm. For growing lettuce: 600-900 ppm. Keep pH at 6.0-6.5 (slightly higher end of the optimal range works well for lettuce).
Change the reservoir every 2-3 weeks. Lettuce that's getting too many nutrients will show brown leaf tips — dilute the solution if you see this.
Harvesting
Lettuce is best harvested using the cut-and-come-again method:
1. Once the plant has 8-10 outer leaves, use clean scissors to cut the outer 3-4 leaves at the base. 2. Leave the inner crown untouched — this is where new growth comes from. 3. Harvest every 5-7 days once established. 4. A single plant can produce harvests for 2-3 months before it eventually bolts (goes to seed).
Signs of Bolting
When lettuce is about to bolt, it sends up a tall central flower stalk and the leaves become bitter. This is triggered by heat and long days. Prevent or delay bolting by keeping the tower in a cooler location during summer, harvesting frequently, and choosing bolt-resistant varieties.
Once a plant has bolted, remove it and replant to keep yields consistent.
Troubleshooting
Yellowing lower leaves: Normal for older leaves, but if new leaves are yellowing, check pH (target 6.0-6.5) and nutrient concentration.
Slimy or mushy roots: Root rot from low oxygen. Check pump timer is working and that reservoir isn't overfull.
Slow growth despite green leaves: Check light levels. Lettuce needs 6-8 hours minimum.