Cold frames are a great way to get the jump on the growing season with your seedlings, without a big outlay of cash. Recently we built a bunch out of re-purposed glass doors and hardwood frames, and they’re working a treat.
Since our last frost is in November, September is still full of icy mornings, which is not good for seedlings. After researching various cold frame designs, we settled on this design based on time, funds and Michael’s previous experience… 
Michael has situated the cold frames just above the bottom dam. It’s a sheltered, north-facing place, relatively flat, and just up from the market garden. Cold frames need to be placed near the daily work as they generally need to be covered at night and opened up a crack during the day so they don’t cook your seedlings.
We’re all pretty happy with this simple design. We didn’t go with strawbale as the surrounding housing as mice love strawbales, and mice and seedlings (as discussed here) do not mix!
The cold frames can also be moved if needed, and should last us many years.
I’m sorry I dont have a picture of the testing process of defining which glass to use, however. One of the parameters for making these was to ensure the glass we used was toughened or laminated, as a big, big sheet of broken glass is obviously not a good thing.
But how exactly do you tell if your recycled glass door is toughened glass? In short, you drop a rock on it.
After smashing several glass doors from our shed stash of building materials, we found several that would fit the bill and last the distance. Huzzah for no big shards of broken glass, should someone drop the lid while opening or closing the cold frames…
The size of a standard glass door also happily fits our bread trays of soil blocked seedlings perfectly. So it’s off into Spring we go, with a jump on the season that will allow us to be harvesting good food sooner…
Dawn Chorus Educational Initiative http://dawnchoruseducationalinitiative.org.uk/
has a number of glass doors & has considerd doing this but working with young children, we have health & safety concerns. However, I would be interested to hear if you have tried it with bevelled glass, used in many doors, as I suspect that, appart from being a problem to clean, they may magnify & burn plants or they may further amplify sunshine in the right conditions.
If safety is an issue you may wish to use a heavy clear tape and criscross the window with it. This will reduce the danger if the glass is broken.
We only used toughened or laminated glass (as explained in the post) for that reason, so we don’t have to worry about breaking… 🙂
Thank you SO much for yet again pointing out a simple way to address a garden problem.
I know you guys are working with a stash of doors you already had, but where would be a good place to start looking for used or discarded glass doors? Or even windows. Thank you!
Claire we got some of them from tip shops, and scrap yards?
what a fantastic idea with the bread crates. so easy to carry around a lot of those little seedling trays!!!
And, if you didn’t have all those little seedling trays, you could just line a bread crate with shade cloth and fill with seed raising mix or your own compost and plant straight into it.
I was curious whether you transplant all your seedlings or just let them grow as is? Seems like they are too cramped to let grow as is.
I notice you’ve lined this with clear plastic, and wondered if you had considered using black instead, as an extra warming factor?
Another milkwood post with a simple idea which is really useful. You guys are awesome
“After smashing several glass doors from our shed stash of building materials…”
haha i love you guys! i can imagine that would have been a fun afternoon of research.
awesome post, kirsten.
bel.
Thank you! I shall start my hunting ^-^ Oh and a happy almost springyness to you guys 🙂
Hey Kirsten nice post 🙂
you have more information on the straw bale design? (and if mouses love strawbale so much how are your strawbale houses surviving the mouse invasion or are they not getting in there?)
also why did you have the plastic sheet in there? for making it more airtight?
thanks and keep it up great stuff!
I was just thinking of doing this myself so decided to have a google… My thought though was to repurpose some old ute canopy window gas struts to prevent the possibility of dropping the doors. Just my 2c
Yep, you could definitely do that!
love the idea if using old bread crates for the seedlings! to make the frame can you use any timber?
I’d avoid treated pine but otherwise, yes 🙂