A greenhouse...kindof.

Found a 8'x8' smoked plastic skylight on craigslist last year.  I haven't gotten around to using it for a greenhouse top, but wanted to share how well it's doing on it's own.  We've been in the single digits on and off for weeks, it's January 21'st and 10F degrees out.  The snow is about 8-10" thick, and there are green plants underneath this skylight.  It IS double pane plexi and smoked, which heats more in the day if it's not snow-covered.  In the summer everything under it dies...and I mean everything, but in the winter...I could see starting some early lettuces under it in maybe mid-February.  There are also MANY more 2'x2' and 4'x4' of this exact type on craigslist every now and then, usually around $50-$100.  I scored mine for $50 because who else will use something like this second hand?!  :O)  Anyway, here's some pics...

What a brilliant idea !

It looks like your sky light will work great for a cold frame,  or as a Hot bed cover.  I did a small hot bed some years ago with single pain glass windows that I was given.  I dug down about 2' and put in some horse poop for heat and sifted back the top soil.  The sides were simply bales of straw.  I piled the rest of the unused dirt around the Bales.  Because your glass is so big you will want an easy way to ventilate the heat out as you get toward spring.  Otherwise you will cook your tender plants.  Some easy way to get into the plants to water and to pick when it gets to be time sould also be in your design for the cold frame.  Since you have 8' to work with I would suggest making a door at the back of the frame,  8' X 8' is pretty large to try and lift each time you want in there to water,  pick, plant work,  etc.  Good luck with your project. 

I did that too with bales and old windows for seedlings in pots.



Then when I'd removed the little pots I planted some pumpkins in the bales under the oak. They did really well and so did the raspberries next to the bales.



I like GPtech skylight idea though because it's strong. I have four dogs and fifty chickens in the garden who get everywhere and the skylight looks like a safer option than the windows.

That set up looks Great Irene.  I only used bales on 3 sides and angled my glass down to the earth on the south side.  I felt I got a little better light and more heat that way.  I had dug down into the ground about 2' so I wasn't worried about the plants growing up and touching the glass.  I was working full time then and had a problem with the thing over heating during the day while I was away though.  So that is why I said you should have an easy way to ventilate the unit once things get warner outside.  Otherwise you will end up cooking alot of tender plants.  That is what I ended up doing,  live a learn,  I dont make mistakes,  I have learning experiences.   

I would like to Thank the Moderators for removing that inappropriate last post.  Iknow that we all want to keep to the topics,  and its Great to see that we have some good people in charge of this group.  Thanks again everyone.    Doug

I've been think of doing something just like this. I was planning on using cement blocks but the hay looks easier and will be a better insulator. This year when I was taking apart the halloween decoration made of hay, corn stalks and such, I noticed some seeds had sprouted under the hay while it was below freezing.

Now to find an old bubble skylight or 2. 

"skylight" in st. louis craigslist, just for reference...the links will go bad after 2/2011 though;    http://stlouis.craigslist.org/mat/2154979832.html ;   http://stlouis.craigslist.org/for/2134316760.html

That's very awesome! I've also seen something similar done with an overturned fish or reptile tank (as long as it's got a clear bottom. What's great is you can even possibly get them for free from anybody tossing out an old tank. Even if somebody is discarding one because it's not watertight anymore, it'll likely do just fine at holding in the warmth and condensation 

great idea..

years ago one of our  neighbors stored his pick up topper on top of a shed frame as a roof..so the topper was made of nearly all windows and a lot of light came into the little tiny shed from the windows..he used it kinda as a cold frame..

also lots of people use USED windows in frames for coldframes placing them over bales of hay as a roof..

i would LOVE to have one of those large ones like you have ..esp double pane..but doubt if i could find one in our area..very cool