As I was beginning the write up describing the NFT - nutrient film technique I realized that quite possibly it would make more sense to come through this door first. I jumped from "Kratky" onto the NFT path back in 2016. I didn't try this until the summer of 2019. This is a very effective and low effort method. Lots of container options and other than the grow deck about as inexpensive as it can be. I now have two of these in a hoop house during the warm weather months.
The key to this approach is Buffer capacity. Your system has considerably more water/nutrient capacity verses the number of plants being grown. Once started it requires little attention for a number of weeks. Unlike a small "Kratky" setup with limited reservoir capacity any large container can be made into a raft. It will require an air pump to oxygenate the system. The photo is nearly self explanatory. It is capable of growing massive lettuce here on Kodiak.
Only three things needed with a raft system… A large container, from here on the pond. Airpump and air stones. The raft. This is simple to make from a sheet of 1" blue insulation board available at most home centers. Here in Kodiak, Spenards sells it but it is frequently out of stock. Use a hole saw and punch 2- 3/4" holes with a hole saw. Try to leave 5 or so inches between the holes. Air flow Air flow Air flow.
A dandy, cultivar Cherokee from Johnny's Seeds grown summer 2020 in the smaller of our two hoop house raft systems. The beauty here is these are off the ground. The only slug issues we had was when a long tendril of New Zealand spinach reached over from a raised bed and created a bridge. Cut out the bridge and the problem stopped.
I'm holding that at arms length to take this picture. I don't keep track of the details as much with these in the hoop house as I do monitoring the NFT on the inside but in general it takes about a week longer to grow the large frame cultivars outside as it does to grow say Oakleaf or Batavian on the inside. One thing for sure though the raft system is my choice for growing the Butterhead varieties. More space between the plant and a deep well for their large root systems. I struggle growing the butterhead inside. Lots of losses to grey mold. Out in the hoop house in the floating raft rarely have any issues. The same applies to the small frame Romaine varieties.
Our two rafts. The large orange one holds 55 gallons of water the smaller white one is around 40 gallons. Pictured here with some Arugula, Lolla Rosa, Muir and a Butterhead variety called Flandria
Our newest addition is a 25 gallon raft inside added in the fall of 2020. Yes lights here for sure. This is spaced for nine cells. I would not try to squeeze more plants in, the airspace between the plants is a good thing. So far it has seen few issues. I have learned a critical item with the raft systems and will detail more shortly
I generally hold the seedlings for an additional period in the germination tray. I want their first adult leaves larger and I want plenty of roots before putting them in the net pot. Similar to holding seedlings for the NFT at what I will soon describe as My "Kindergarten" phase under the NFT description. The image below is an example. The roots are much more developed and with the second adult leaf set well developed.
3181 Mill Bay Rd. #1 Kodiak Alaska 99615