Howdy, Bill!

May I suggest that you make a trial bed--even planting it with dried beans or peas from the grocery store, if you want to be really cheap, heh. You could also leave it unplanted, for "worst-case" scenarios where beds have no roots to hold them together. Be sure the mix is well-watered-at least until the damp-sponge stage, so it settles in snugly.

Now leave it to weather, or simulate the weather conditions with a sprinkler and hose. See what happens.

I think even a 2x2 bed would give you an idea of what you can expect. You should be able to reclaim (or corral) at least most of your mix....

Also consider using expanded shale instead of vermiculite for better soil retention and stability over time. Coir fiber, or even finely shredded composting leaves, might be better than 1/3 peat moss, too.

If you need side support, consider planting very short herbs that are not offended by Floridian conditions. Imagine, all the garlic chives a body could ever need.... Heh. In a raised bed, thyme might even be happy. Other ideas include low border flowers (grown from seed, not chemically treated bedding plants)--although you have to think about bees and such, too.

All the best, and please report on how it goes. We're all "rooting" for you.

Personally, i wouldn't on a slope. Nature has a way of leveling things out. Shiuld I do a bed like this, I would use at least a 2 x 4 frame to keep the erosion contained.

Jacque,

I wish I could find a local source for expanded shale or coir.

I took your advice and went out and made a very small trial bed. I made a small mound (2'X 2', 8" high)and shaped it with a flat top and sloped sides. I patted it down a little, then poured water from a watering can onto it--and watched the soil mix wash away. Even when I had everything level, it wants to flatten out, as Rain says. I suppose if the bed were bigger and more established and had some garlic chives planted around it, it would stay in place, but. . . I think I'm going to go with cinder block sides. I'm going with the Mel's mix because I've had such bad experience trying to grow veggies in this sand, and now I'm a bit paranoid I guess about getting the sand mixed up in my growing mix and vice versa. If I were working with the sand, ammending it, I wouldn't care so much about a little washing away and I think the mound technique would work pretty well, though.

Thanks for your help. Please let me know if you (or any of you out there) knows where I can find expanded shale and especially coir.

Bill