I am trying to rebuild my AP system.
I have converted to a raft growbed using hydroton clay pebbles for media. To start seeds, I have placed the pots in a plastic shoebox with water, covered to keep the media moist.
So far I have placed seed for Basil, Oregano, Parsley, Dill, Romaine lettuce, Spinach, and a fancy mix lettuce. The only seeds to germinate were the mix so far.
My question: Can all of the above plants be seeded straight to the hydroton, or do I need to start elsewhere and transfer seedlings?
I've never used hydroton but direct seed into gravel a lot.
It has been my experience that small seeds directly sowed into hydroton get washed down with the Flood/Drain cycle.
I use rockwool to put the little seeds into. You can put the rockwool directly into the hydroton buried about 1/2 way so that they will wick moisture but wont let the little seeds get washed away. Just soak the rockwool first as per instructions. The plant can grow to maturity right in the rockwool.
Large seeds like Melon seeds go direct with no washing away issues.
I usually start my smaller seeds in a seed starter mix (traditional dirt/compost and seed tray) then transfer the seedlings into the hydroton grow bed when they are about 2 inches tall. Small seeds just get flushed down the siphon when direct seeded.
I've had good luck sowing lettuce-ish seeds directly into the hydrogen. Spinach too. But cilantro and basil seeds never came up.