Shalom - may want to consider 1" foam insullation boards they have at the box stores - cut to shape , use a couple/ few layers for bouancy, cut holes for plant pots and you can adjust the height of the plant above the water, cover bare spots with spray adhesive and cover with pea grave,l dirt, dried moss, etc., to get the affect you want. couple smaller layers on the underside for bouancy, they will float and if large enough not tip over when the plants get grown. I don't have a way to calculate how much is needed for the bouancy - you're on your own for that.
By adjusting the height of the plant pot it gives the ability to use numerous land plants, depending on how much water they can stand - On the watergarden forum, there's a thread with a picture of a beautiful island.
I currently, have 3 floating islands,made them from light grating, cut to size, wire tied pieces together to get the shape wanted.. Laid them flat and sprayed great stuff on the bottom for bouancy, when dried turn it over spraying the top side, and as the foam expanded I stuck pea gravel sand into the great stuff. Once the foam was dried, cut it with a knife where needed. Nature and air pollution also contributed to darking the foam. I did cut the holes in the grating before foaming-used a pair of wire nippers
I have impatiens, marigolds, creeping jew, hosta, 5star ground cover, bluestars, and a burgandy colored plant I think is Auselonea(?)
McKool
