Lettuce using the floating raft method

[Kangaroo1943]

I am growing lettuce in a styrene tray and using the lid as the floating raft. I am growing outside under my roof eaves but still getting lots of sun, heat , and not completely away from rain wind etc.
The results so far are good even with today's temperature of 32C.
This is using the Kratky method with no pumps air stone etc.

[rainbowgardener]

Can't argue with results. I would have thought 32 deg (= 90 F) is too hot for lettuce and your location too sunny in that heat. And I never understand Kratky method and why it isn't just stagnant water (other people have written in here about it).

But your lettuce looks great!

Do you worry about growing in styrofoam, especially in that heat? "It was observed that temperature played a major role in the leaching of styrene monomer [and other aromatic compounds] from Styrofoam cups" https://www.ncbi.nlm.nih.gov/pubmed/17915704

At least some plants are used in phyto-remediation to help clean air or water of toxic chemicals, because they can uptake them. "One pot of Chlorophytum in 200 square foot room is enough to perform as an air filter, which releases oxygen and absorbs carcinogens like formaldehyde and styrene. ...Ivy is the most effective indoor plant in absorbing formaldehyde. It also absorbs harmful substances like benzene [and styrene]. In 24 hours, ivy can absorb 90% of indoor benzene." https://thisgreenearth.wordpress.com/20 ... r-quality/

[Kangaroo1943]

I grow most of my plants either DWC , Drip system, and Ebb and flow all with the same success, this lettuce experiment is growing alongside my DWC with Silver Beet, and Chinese vegetables.
Brisbane is in the subtropics and this is our hot and stormy time of the year.
I have not lost one plant in all this year. I start my seedlings in soil and wash off all excess soil and plant into expanded clay and sometimes in rockwool for smaller seedlings, but the lettuce I listed is growing in perlite with the bottom of the roots just touching the nutrients.

[imafan26]

Heat usually causes lettuce to bolt. Even heat resistant lettuce will bolt sooner in the heat. You usually have the biggest problem when the the lettuce starts to head up that is when you get the problems with tip burn and bolting. Just watch the lettuce and harvest a little early. We did have better results by shading but growing in morning sun and afternoon shade will help that.

Lettuce is a low nutrient requirement plant. Kratky method works fairly well with that. We used to change the solution weekly because we used the bottle method and the evaporation caused the solution to evaporate too fast. With the floating raft there should not be that problem.

[Kangaroo1943]

Thanks for your input, we had another scorcher yesterday and my plants which are growing beside a brick wall looked a little sad , I put a shade cloth over these 5 trays and they look good.
The lettuce is looking good with no tip burn and has not bolted yet and I am ready to harvest using the outside leaves first.
The styrene tray nutrient level has dropped about 3" in the last week and the roots are already well into the nutrient mix.
It would appear that the styrene allows the nutrients to keep cool so possibly that is why my plants are doing well.
My DWC trays growing alongside are really depleting in nutrients with this hot weather, and I have to keep topping up and refreshing much more often.

[imafan26]

tip burn usually starts when you see the lettuce trying to head up. Harvesting the outer leaves is a good idea.

we used net pots on the rafts. The lettuce was grown in oasis plugs and the plugs put in the empty net pot. Holes in the styrofoam was drilled with a hole saw. The cups fit in the holes and the styrofoam was a double layer so only about 1/2 inch of the bottom of the cups actually was in the water. That left the air gap that was needed for the aerial roots to form.