I will be growing lettuce hydroponically using an NFT system and HO 54w T5 6500k lights. I will be using an organic nutrient solution (AN Iguana Grow) as well.

I have ordered some certified organic seeds, and on the website it listed the maturity days.

For instance, the Gandhi Butterhead lettuce says "Matures in 70 days. (open pollinated seeds)"

Is that 70 days from seed to finish? How much time should I knock off for growing hydroponically over soil? How do I know when it is ready for harvest?


1 Answer 1


I don't know anything about hydroponics, so I can't answer the part of your question about "knocking off" time for growing hydroponically.

When seed packets say "matures in XX days", they're referring to the time you put it in the ground. For plants that are usually directly planted (e.g. corn, beans, carrots) this is the time between putting seed in soil and harvest. For plants that are usually transplanted (e.g. tomatoes), this is the time between transplanting to ground and harvest. I think lettuce usually falls in the former category (the seed packets usually tell you to direct-seed), even though transplanting is not uncommon. For hydroponics, "in the ground" is a bit different, but the principle is the same.

Lettuce is generally ready to harvest when it looks ready: you can harvest "baby" greens for salads when they are 3-4" tall, or you can wait until the head is formed (for head lettuce) or the leaves are full size (for leaf lettuce). In my experience it's better to harvest early than late, since letting it go too long will generally result in bitter flavor and runs the risk of bolting.

  • Thanks for the information! Almost ready to start, just waiting for my TDS meter to ensure proper nutrient levels!
    – Kray
    Sep 11, 2012 at 18:12

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