Hi lhhgbh,

On my web site from Australia, I use coarse sand as a medium for supporting hydroponic plants.

If you save each page of my web site as its own name, onto your computer, all in the one directory, you will be able to navigate from page to page in a flash, when you are off-line.

Cheers,
Jimr007
Australia.

Here is a link that might be useful: Simple Sand Hydroponics

If they are flimsy they probably need light. Hopefully they are not damping off, but it is hard to tell from a description. If you are seriously concerned, you can post a picture. They should not need too much support at the size you describe. I put my tomatoes in at about 6 inches. I have a setup where I can use garden wire. I get 3 rolls for $1.00, so, for me, it is a cheap method.