I know there are dioxins (a known carcinogen) found in all PVC-based materials, which includes composite decking. Personally, I would not be comfortable using it in my garden.

This past spring we built some planters 2 feet off of the ground, 6 inches deep. I used a mix very similar to Mel's Mix. The compost I added was 3 different brands of "box-store" humus-n-manure type products. I used a double measure of the various "composts" (calling them compost is a compliment they don't deserve) than I did of either vermiculite or peat. As our reliable friend Violet recommends, I mulched heavily. I wish I had used or purchased more high-quality compost! It seems as though my garden is suffering from a severe nutrient deficiency as a result of store-bought compost only. If there is one area I would suggest you concentrate your efforts, find some good, healthy, nutritious organic material to add to your mix. I now wish I hadn't used any peat. I mean, it's void of nutrients, it seems it's only value is moisture retention and, compost performs that task better (I believe) plus, "real" compost has nutients in it. We are experiencing record heat, here near New Orleans. My mix is not at all drying out quickly. I'd have to look at our temps the past few weeks but, I think we got into the mid-to-high 90's every day for 3 weeks. If drying-out were "MY" main concern, I'd add more vermiculite. But again, I believe a generous amount of good compost will do all you're asking.

Well said justaguy2. I suggest not screwing and unscrewing if you don't have to. You'll increase longevity if you just leave as is. The frame won't be that heavy at all. As for holes, not sure, maybe someone will have a suggestion. Off the top of my head I'd say an ice pick or something that wouldn't turn into a "rip" if that would even happen, maybe Xs would be fine with a knife. If you do line with no bottom, consider corner drainage instead of directly in the bottom center area. Maybe you could even build the box, line the box, fill with soil, and then drill some holes in the sides along the bottom. Just an idea... Sounds like all you need to do is get started!

Well, I'm glad I asked. I was very unsure about a whole bed of tom's. I think istead I can fit a 16' long box and just do the back tom's and then I will have room up front for other stuff. The middle of the box will get about 9 hours of direct sun and the oppisite ends about 7 hours. I won't be able to do as many, but I'm hoping next summer we can also get the other side of our yard fenced. My one neighbor on the other side (the side that gets a little more sun, GRRRRRRR) has a habit of mowing way over onto our yard when we are not home among other things and I could fit another 16'x4' box over there too, not next summer, but maybe the following one if we can fence next summer. As for the hanging tom's, I do think that's really neat, but have no place to hang and my hubby doesn't like the look of pots or buckets. I did buckets last year with some peppers so I could line the driveway with them thinking they would like the bounce back of heat off the asphalt, but my hubby hated the look of them.