Backyard Aquaponics
A place to discuss aquaponics

Does anyone know what the lowest water temperature lettuce will grow in? I'm not just curious on what the lettuce could handle, but more of what the lowest Temps it can thrive in. Thanks

I do not have your answer but a add on question.
This would be good info I would like to know the coldest and the warmest.

I was going to try to keep mine 70 F 21 C.

Lettuce is a cool-weather crop. According to bonnieplants.com, lettuce grows best between 45° F and 80° F.

The challenge with growing at 45° F in aquaponics is that your bacteria won't be very active at that temperature.

Bacteria growth rate is decreased by 75% at 46-50° F. No activity will occur at 39° F (4° C).

To my understanding, there's a difference between what the top of the plant and the root zone can handle. I read somewhere that lettuce can can Temps as low as 65F in the root zone... this seems pretty high to me, but I definitely overlooked the bacteria factor.

My goal is to loop out several 200' pex tubes at 10' deep. I'm not sure how many but the plan is to use as many as it takes to use the earth as a constant water cooler. If these lines loop out from and return to the trout tank, I think I can achieve their optimal temp range. Finding a happy bacteria for this temp range might prove to be impossible. I may have to implement some sort of exchange tank to buffer the water temperature between the DWC and fish tanks..

The bacteria that will grow in those conditions and process waste already exist and having your system at that temp will select for them so you just need to provide them a food source and enough time to get established.

Lettuce will grow at very low tempratures. My system has averaged 5c last week and the lettuce was still growing (although it was very slow)