Dose of physics: Clear containers will warm soil fastest. When using black containers, the container absorbs the suns light & turns it to heat. Some of it is conducted to the soil, but more is lost via radiant transfer to air surrounding the container walls, then dissipated by convection. Clear containers, on the other hand, allow (a portion of) the light to pass through the container where it strikes soil before turning to heat. The container walls then act more as an insulator than a radiator. The difference in temperatures can be very pronounced, varying by as much as 30* F. or more (my estimation), even under normal growing conditions. Container shape also has a big impact on solar gain. A practical application of the principle is tinted glass in a car. Tinted glass represents the darker container, & clear glass of course the clear. Are you warmer in the car with clear glass or tinted glass? Answer - clear. The tinted glass absorbs light before it can strike an object inside the car & be turned to heat. The heat is then lost to the outside air, as above, instead of heating the car. So from warm to cool: clear - black - through increasingly lighter containers until you get to white, the second coolest. Coolest would be a container with a reflective surface - mirror-like or coated with aluminum foil. You didn't hi-jack the thread. It's still on topic, even if Esme didn't realize it when asking question originally. ;o) Al

TIN CANS, GUYS, TIN CANS. I have one of those can openers that leave a smooth edge. Around the OUTSIDE at the bottom (so the water can get in when I bottom water), I put 3 or 4 holes with a big nail (balance the can on a cushion and bang away)... they are GREAT... Then, when you're done transplanting outside, recycle the cans. They're sturdy and grrrreat! Best, Homegrown

It's so coincidental you would post this...I was just reading a bamboo Web site today, and they recommended a 2" layer of styrofoam inside a pot to insulate varieties that were not hardy in your zone. I don't know about bubble wrap, but same principle.

Here's a bit more info to give you a better idea. Zone 5B, Cold winters, hot summers (rarely humid but like this year...humid and hot summer!) My walls will be 2x6 with either dense fiberglass or mineral wool insulation (products readily available locally). My current debate among my thoughts is trying to decide about the WRB (MY HOUSEWRAP) and at what tier/level/plane to install it (Or even two). Windows are not permanent, and in a forever home (God willing), windows will need to be replaced in the same lifetime I live. Therefor, I don't want to choose some method that would hinder future upgrades/replacement. (Such as installing foam over a flange so it must be cut out, or installing a type of flashing that requires more of the foam wall or window box to be torn out to replace the next time around. I am debating between a quality house wrap to prevent moisture and also act as an *air* barrier not a *vapor* barrier. Basically, on a cool winter day with 50 MPH Wind, I don't want that wind (air) easily permeating through the house because I will a.) not be sealing the joints of foam b.) possibly not even taping the foam joints c.)not going to use any internal poly as a air or vapor barrier. I am not sealing the foam joints because foam shrinks and expands and those joints will not stay tight forever. If I have the luxury, I will install (2) layers of 1" thick versus (1) layer of 2" thick to provide staggered joints and prevent air from moving inwards that much more. There is a wealth of information on greenbuildingadvisor, but it seems to boil down to personal preference on two things. One being that I can opt for innie (windows set towards the OSB wall sheathing layer) or outie (windows that are at the most exterior plane as possible). And we all know that flashing a window opening is important for multiple reasons, and that the standard way includes integrating your house wrap (WRB) into the rough opening with multiple methods. I would like to use a flexible peel & stick flashing that will seal to/against the house wrap. My concerns for those who have rigid foam on the exterior are a.)where did you locate a house wrap (Or WRB)? and b.)in what fashion did you set your windows? It varies by foam thickness, but generally 1.5"+ of foam requires framing out a window frame/buck for window support whereas under 1.5" doesn't seem to need the additional support. And of course the other option is the fasten the window like standard construction, on the sheathing level right against the sheathing (osb in my situation) and into the studs. This would then mean I would either use the WRB at the same time to detail the window opening, or perhaps not. But also means I would have to design a custom flashing to cover the exposed foam around the window, since the window is set inside from the foam and siding. I am surprised house wrap (a WRB) seems to not be the norm. It is here...and it is something I do not want to overlook. My understanding is that in new construction with rigid on the outside, builders extend the window opening (like you said Mushcreek) to the same thickness as the foam, therefore that foam will not have an exposed edge. I read on GBA that instead people build plywood boxes for the windows the thickness of the foam + 3/4" and then use a 1x3 or 1x4 flat around the window opening fastened thru the foam into the window opening studs. Then the window flange is fastened to this flat 1x3 or 1x4 frame, and it also brings the window out the extra 3/4" so that 3/4" firing strips can be used to install siding. I do not think house wrap *over* the extended window frame would be as effective as if I just installed the windows flush with the foam level, allowing my flexible sticky flashing tape to easily fold over the opening and adhere to the foam. ---starting to think I should just not be so concerned about this detail. Turning my hair grey.