Lettuce in hot weather?

[David J]

I'm awed by the lettuce growing I see in the pages of the AP websites. Many AP'ers are in hot climates in Australia. Can you grow lettuce on a raft system when the outside temps are 38 degrees? What are the temperature ranges for growing lettuce in an AP system?

[Hotrodmike]

David
It's more the type of lettuce than the AP system . There are different strains and types for your situation . There are ones bred just for greenhouses and there are ones for cold and hot weather . I have even found heat tolerant head lettuce .
Have A Kind Day
Mike

[Murray]

The open leaf types are much better to grow than the old "Iceberg" Evidently they have much more food value as well.
Try some different types, there will be an open leaf type that will grow well for you.
I get best results with "Oakleaf" green and red. Also "Red Butter" goes well also.
But you do get better results all round in winter than summer

Green Oakleaf in photo below.

[David J]

Thanks Mike and Murray,

Murray's DVD talks about harvesting a rotating crop with a 4 week growing cycle. What variety of lettuce is that, and is it 4 weeks from seeding or transplant? Does lettuce grow faster in a raft system?

[Murray]

Lettuce is fairly predictable in it's growing cycle. There are small variations from lettuce type to lettuce type and summer to winter, but generally it is 28 days from seed to seedling and 28 days from seedling to mature plant. A well organised grower can get 13 rotations a year.

So, in your seedling raising area you will work on a 4 week cycle and in your grow out system you will work on a 4 week cycle.

Lettuce grows great in a regular gravel grow bed, and it grows fantastically well in floating raft.
We have documented trials showing that lettuce grows around 10% faster in floating raft than in regular grow beds.

[bigdaddy]

Hi folks,

I'm growing cos lettuce and butternut crunch,both in an cottage stones and also cottage stones topped with about 100 mm of expanded clay,in a brand new grow bed.I've found the cos lettuce falls over in the expanded clay, particularly when it rains and gets windy, but is just fine in the cottage pebbles,It's freezing here right now,and they are doing OK.I'll probably harvest them in 2 or 3 weeks.
don't forget I have a brand new system so it will take a while for it to mature.
I think the lettuce grows quicker in my cottage stones,but not by much,so far.

I aim to grow lettuce in the summer but that is probably 6 months away to being able to tell if the lettuce can handle our aggressive summers.

Cheers.

[DaveOponic]

I grow lettuce in the tropics. It's always a challenge. i now have an undercover, tube lit growbed with fans to cool the plants. I have grown it in an NFT system here hydroponically with some success. I don't play with fertilisers anymore though. All depends on the variety I think. The curly lettuces grow well here. It's something I don't grow much of because we don't need to. there is a big Hydro. farm here run by Thai operators and they grow it in floating raft with evaporative trickle cooling using huge fans that circulate cooler air around the plants.