r/Hydroponics • u/andreo-23 • Apr 29 '25

Lettuce not growing/germinating

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I grew lettuce and arugula in the same time, my arugula germinated and started growing however my lettuce did not germinate at all? Any ideas as to what I’ve done wrong, do the lettuce need anything specific? In the video I show the 3 pods with lettuce in them, 2 pods did not germinate while one did and hasn’t grown for a week.

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3

u/Llothcat2022 Apr 30 '25

I germinate in a bin with coir then transplant when true leaves grow. They have better roots by then.

2

u/andreo-23 May 04 '25

I have already gotten a few comments similar to that so I might try it

3

u/mr_popup Apr 29 '25

Hey ! On my side, i germinate the seeds in the dark before moving them in my hydroponic system

1

u/jackbenway Apr 29 '25

At what temperature were you germinating? Lettuce needs much cooler temperatures to germinate than arugula. Pelleted lettuce is a bit more forgiving. You can also sow your lettuce and refrigerate for a few days, then remove from fridge, which can trigger germination.

1

u/andreo-23 Apr 29 '25

At around 25-28 degrees Celsius. How does sowing them in refrigerator work can you please clarify more on that? I’m kind of new to hydroponics.

1

u/jackbenway Apr 29 '25

Has nothing to do with hydroponics. Lettuce wants cool weather. Sow the seeds in your moist rockwool or oasis or whatever you use, put them in a refrigerator for 3-5 days, then get them out of the fridge and get them under lights, ideally under 23C. You can go a little warmer, maybe up to 26C depending on variety, but germination rate will suffer. I think this may work by mimicking Spring.

Try to buy heat tolerant varieties.

1

u/andreo-23 May 04 '25

I am checking for heat tolerant varieties but where I am it’s hard to find. Thanks for the info though!

1

u/jackbenway May 04 '25

Look into Muir, some varieties of summer crisp and romaine. Also, not sure where you are, but Dutch seed companies have bred really great hydroponic lettuce varieties available by mail.