Well the general rule in container gardening is that the containers must have some form of drainage. Otherwise the water collects in the bottom, you get ponding of the water, bacterial growth, and root rot. I can't really picture containers made from "wire forms and concrete". That would be quite unusual IME but I would be worried about that weight on the field interfering with drainage in the field. Given all the drainage problems and shallow drain fields one reads about in many parts of Florida, especially with sandy soil, I'd be very reluctant to alter my septic drain field at all. And there are literally thousands of lightweight containers with drainage holes available for gardeners to use that can be easily moved and adjusted for sun exposure without creating problems for the filed. Unlike in-ground gardening Container Gardening has its own set of unique needs so I'd suggest some in-depth reading over on the Container Gardening forum here. Dave

I, too, plant even more than you--- 12 plants in a 4 x 6 bed. That's only 2 sq feet per plant, but it works. It works because my soil is dug very deeply (18") It is heavily composted, and I am religious about tying them up in a basket weave pattern of support (google it). Yes, it is a jungle by the end of the season, but I can reach everything, and my tomatoes are never sunscalded because there is more than enough shade from all the leaves!! Gardening is about experimenting with what works for you! You have had advice from both sides of the aisle on this one, so plant them, and then you will know how comfortable you are doing the same thing next year!!

Thank you for the follow up post (laceyvail) but I don't feel like that answered my question. I know its late but gardening is about trial & error? Most of the "Greens" I am planning on planting can survive on less than 10 hours of daylight. In Mass, I still have 10 hours of daylight until mid November and then I never have less than 9 hours even up to the winter solstice so although I agree that my greens will not be their best I do believe they will grow, even getting them in this late. I could get lucky and not see a heavy prolonged freeze for some time. Its a roll of the dice I'm willing to try for a few seeds in trays. What I'm not willing to roll the dice on is ruining my 2015 Garlic crop. So back to my original question: Can I plant on top of my newly seeded garlic? or (to ask a different way), will the roots of leafy greens adversely affect my 2015 Garlic crop, which is planted at a depth of 6-8 inches? Looking forward to hearing from the GW community. Thanks again in advance.

When I checked yesterday the corners of the bed where black with ants, all in the crevasses where the cedar boards meet. The soil was crawling and I'm not exaggerating, its like the bed IS an ant hill. This morning my husband says he's figured-out what they're going bananas over: He whipped the corners with mineral oil to prevent the wood from splitting. I had tried to see whether they liked fatty or sugary treats and they definitely loved the sugar and ignored the peanut butter. But there's surely something in that oil that they like. A lot.