Trying to keep things growing in the winter
Hi. I have a coldframe I built over one of my garden beds which is basically an a-frame with clear plastic draped over it. Last year I planted it in September and my plants grew a little but by November had pretty much stopped growing and they didn't start growing again until early March (and took off in April). I planted around the same time this year (when space opened up in September from a harvest of summer grown crops). I'm looking into ways to potentially get the stuff to grow a little more this year. It currently has carrots, arugula and radishes with some mache being started indoors that I will plant out there soon. I have mulched some leaves from a honeylocust tree around the plants hoping that this will help keep the soil slightly warmer.
My first question is could the lack of growth last year just be due to less light during the winter months? The coldframe is in our sunniest spot which gets about 3/4 of a days light, with that much light is it possible that it is only enough to keep the plants alive and there is no way they will grow even with warmer temperatures?
If the issue is really about keeping the plants warm what else can I do to warm it up without electricity? I was thinking about trying a manure heated hotbed next year.
For this year I was thinking about painting milk jugs black and putting them in there to absorb heat during the day and release it at night. I was wondering how well this actually works?
The other question I have about the milk jugs is if there is a hard freeze at night and the water in the jugs freezes does it then work against you and cool the coldframe during the day or is this unlikely to happen in the relatively mild climate of western oregon?
I'm really just trying to explore all my options to maintain a small winter garden that will actually produce in the middle of the winter rather than having to wait until spring for the plants to grow.