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Improvised DIY cold frame

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Hi everyone!

With winter fast approaching, I was thinking about the best way to protect my outdoor CPs from the worst of the weather.

I have an unused single pane of glass . It was originally part of the window in the shed but the frame was damaged and later replaced and this piece of glass got left behind with no purpose (it's just a normal glass, approx. 5 mm thick, I'm guessing it's not hardened or anything as the other pane broke into several large jagged pieces). Could that be used to make a improvised cold frame? I have a large plastic box (the kind local council gives people to put their recyclables into for collection). It's cracked but still in strong.

The glass pane would fit inside the box. I was thinking putting compost at the bottom (partly for insulation, party for extra weight so the box doesn't blow away in strong wind), then placing my CPs in their pots in the water tray on top of the compost. A few bricks along the front on the inside of the box to sit the glass on, the back end of the glass leaning against the wall behind the box (I'll probably have to tie it down with a string or something so it doesn't move when it's windy). There will be gaps on both sided of the glass for air circulation.

I just want to protect the plants from the worst of the winter rain/wind/snow. There are 7 pots (1x darlingtonia, 1x sarracenia purpurea ssp. purpurea, 3x VFTs, 2x drosera binata) and none of the plants are taller than 20 cm.

Will this do?


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Hi Bluedog,

Sorry this one slipped through the net (~8

Have you gone ahead with this plan?

How cold do you normally expect it to get where you are in the winter? The Sara purp purp will have no problems, it grows naturally way up into Canada. The Darlingtonia, to my knowledge and experience is hardy, and so are the VFTs. I'm not sure about the D. binata, I think it dies back but the roots survive and sprout the following spring.  Your setup sounds reasonable, good ventilation is important because if the sun gets on them under glass the temperature will rocket. I'm not sure if it's all necessary though. submerging the pots in compost is a good idea to give the roots protection, and VFTs don't like windy conditions. They won't need to stand in water through the winter, just so long as they don't get dry.

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yes, I got it set up in early November. 

So far this winter we had a week of constant frost in mid-December (around -4 C at night and barely above zero during the day, the top inch of soil in plant pots left on the patio was frozen solid) but the CPs in this cold frame were still frost free. Every now and then there is the odd frosty night but nothing too serious. Overheating is not an issue either. Even with the sun shining the temperature inside doesn't go above 15 C and humidity is around 70-85% (it only gets around 4 hours of direct sunlight at this time of the year). Generally, the temperature inside the cold frame is 5 C higher than outside.

S. Purpurea and Darlingtonia look good with a bit of die back of the oldest pitchers, VFTs are definitely dormant as no new leaves produced since October and old ones are turning black. Both D. Binatas have died back (but the stray Utric is still green). I did water the plants twice since the set up day, but there is no standing water. There is no sign of mould/fungus. I did remove all dead leaves/pitchers prior to putting the plants in to improve air movement.

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