boxcar, The foam is waterproof, so if you lay it under crushed stone with no place to drain; it won't. However, if you have the patience to fiddle with the crushed stone, grading and packing it firmly to the center or one end and can dig out a drywell, you could lay the foam over it, leaving the top of the drywell open from the foam, then more stone on top, and the water would drain to the drywell. But it would result in a much nicer and easier to keep clean floor, not to mention tracking the stuff, to just overlay the foam with concrete patio blocks or bricks. As long as the crushed stone is well and truly packed, the foam really will support the bricks or blocks, that will lay easily and could be butted tightly to avoid the need to fill between them. You could even broom mortar into any cracks, wet it and when it dried, would have a really solid floor. BTW, just in case you aren't familiar with drywells- They are just holes dug down to below frost line, lined in the old days with mortared brick or stones and now, plastic liners that can be bought for the purpose. Or, you can use a length of fairly wide plastic culvert pipe. You could also use the same heavy plastic channel drain as I did, except that instead of the section with the drain drop leading to a sump pit, it would go directly into a drywell. There are a number of options, but for any drywell, always- the deeper the better, then fill it with large stones to the top of the liner and either set a made for the purpose cap or channel drain drop section over it, or top it off with with 1/2 inch hardward cloth and lay a piece of window screening over that, to prevent anything other than water from seeping into it. I drain my GH with a channel drain that connects to a sump pit, fitted with a sump pump, that empties the pit to a 150 ft. long line, but I fitted out my GH out to serve as a tropical fish hatchery, so often need to dump hundreds of gallons of water at a time, and have a large utility sink out there too, with H & C water, so it's a different GH use and set-up than most. I also laid OSB over the foam, then topped that with 3/4 inch concrete board, but that was because I wanted a glazed quarry tile floor and it requires far more elaborate under pinnings than do patio blocks or bricks. The tile also lines the kneewall, but there too, my needs were different. All you really need for a GH in which you only grow plants, is a means to drain off excess water from the plants and avoid too much dampness that might cause fungus on them as well as the interior walls of the GH, although the ability to hose down a concrete block or brick floor with cold water is a nice extra, for keeping the GH clean and help cool it on hot days. It really all depends on HOW you want to use your GH, and WHEN in relation to your climate, and how much time, effort and money you are willing/able to spend to fit it out for your own maximum use and enjoyment. After all, a garden GH is really only for pleasure, because unless you are feeding an army of kids, for what it costs to build and maintain one, it's cheaper to shop for veggies at Whole Foods and buy started plants at any nursery. So by all means, put a lot of thought and effort into your foundation and if, after you have the GH you need to back off on the fittings until your wallet recoups; do so and in the end, you will have what you really want. We spent an entire season preparing the foundation for my GH and by the time we actually got to erecting it, all we had time for before winter set in was to install the heater, but as anxious as I was to use it, patience paid off. (Of course, we are also a pair of arthritic old poops, so everything takes us longer now.)

garnetmoth yes I'm very excited about doing this and also have been reading. I bought some DVD's and books online but have been so busy trying to get things setup. Not sure if you read this in any post but I have a bunch of rescued farm amimals that need pens and to be moved. That means certificates, blah blah, vets, etc. What a pain! THEN there's the greenhouse. I'm sure I'll get more active with this the end of the year right after Dec 15th when we cut off shipping for the year. Nov-Dec is our most busy time. I plan on taking a few weeks just to plow into aquaculture. I'll use the water for my citrus but also starting up organic herbs. In fact I am hoping to make all my citrus organic one day. That would mean that they come directly from the grove 1 gallon newly grafted then potted into CHC, water with fresh spring water and fish poop and grown organically until they are ot the door. I was in the fish market today buying flounder and saw a fish I need to try next trip and if I like it I might try growing it. Have you ever heard of North Carolina Red Trout? It looked a little like salmon. Ok so with help from some sweethearts who email me I'm putting the greenhouse north and south. I'm having a dirt guy grade a raised platform, cover with rock and that's where the first greenhouse goes. It's going to be plum full too. I'll take and post pictures soon.

With help & experience of my fellow GW friends, I have ruled out 2 of my three choices above. I am now thinking about either getting the SpringHouse model or one of the small PlantHouse, StarterHouse, SeedHouse or Plant Tower models on This Page. I would so so much rather have the SpringHouse & it appears to have great reviews compared to what were my other two choices above. No one on here, so far, has said anything bad about their experiences with it. It appears to be better constructed than the "First Choice" & "Yet Another Choice" linked ones above in my original post. So, please let me know your final opinions on my newest choices. =) Keeping in mind, I not only want it for the early season seed starting (which is about all i'd be able to do in the smaller ones), but also for Winter tropicals storage, non-hardy plant storage & kind of a workshop of sorts for propagation, etc.. Thanks! - Steve

yes they will, anything above absolute zero will radiate heat :) Plants perception of heat is a different to humans but if you sit in a hot tub outside in the winter surrounded by snow you wont feel cold. A lot of plants will push through the snow when they germinate, if the soil is too cold they wont germinate :) http://gardenandgreenhouse.net/index.php/past-issues-mainmenu-18/21-2008-garden-greenhouse/january-february-2008/146-using-bottom-heat