Backyard Aquaponics
A place to discuss aquaponics

Hey there, just wondering if anyone has had the problem with their lettuces not forming hearts?? i think it may be that they are not growing fast enough?? What sort of time are you guys growing a lettuce from seed or seedling in??
I am running to separate systems 1 older than the other but only by a couple months. I am growing in gravel in both F&D and CF and also growing in DWC but all seem to be same. Maybe its just that time of year?? I am Gold Coast QLD.

I find that mine tends to bolt in summer in Perth and don't form any hearts. Also tend to be quite bitter.

In winter it is 8 weeks from sowing to harvest in the DWC.

I find mine do the same .The only ones that are any good are oakleaf if you like them .

Are they getting too much sun?

They may have early on but now have 60% shade cloth over them so now they are fine but not still no hearts.

I'm pretty sure it's the weather that's doing it.

Try a few different varieties. There is no shortage of lettuce out there.

Here are some pics from this morning. They look health but just no hearts. There are 4 varieties of lettuce in these pics and a pac choy, but only 1 variety has no heart, the other 3 all have hearts. 1 normal iceberg variety, 1 baby iceberg variety and 1 cos variety.

And here a pic with the shade over it.

And here a pic with the shade over it.

Hi Kitacooch,you will find it's temperature related,what is your water temp ? Ideal for lettuce is 22 c this will help,for myself because of our temps through the hot season,we had 38c yesterday and I think similar today,I had to hunt through varieties that are resistant to bolting, Grand Rapids and Green Oak are our choice. Green oak formed beautiful tight hearts last year in the cold season. Cold season is 10c first thing to 28ish afternoons,my water temp is between 22- 25 at the moment.

The Cos are the only ones that grow well for me. Still have to catch them before they go to seed in the heat.

Thanks guys, not sure of my water temps but it is pretty warm in the green house so i think it is temp based, i guess i will find out as it cools down. My cos are struggling also, they are bolting before forming hearts. Def going to have to get good shade sorted for next summer.

Commercial Hydroponic production keep there nutrient mix at 22c they cool if it goes above this and heat if it drops,air temps are maintained at 24c during the day 19c at night. They have found that if they reduce there water temp to 20c the lettuce will take a air temp higher than 24c.
Iam struggling now coming into the hot season water temp is now reaching 25.5 in the afternoon,air temp yesterday was 34c and its going to get hotter,we were over in the East the other day and it topped 37c.

Thanks dasboot handy to know those temps, i will start monitoring this week when i get some thermometers in place. Am sure at least the air temps are well over 22c during the day, i was sweating my arse of while doing some work in there.

I agree with the water temps probably being the culprit. Some lettuces form much better heads than others so it also may be a variety issue. Something like a Bibb or butter head will head up much better than an oak leaf.