Hoop-frame greenhouses are amazing! If you’ve been following my blog for long, you know I love my greenhouse. But as good as it is, I wanted to make it even better. I wanted to extended my growing season without adding a the cost of a heater. In 2009 I tried using milk jugs full of water to hold the heat and slowly release it through the cool of night. That worked pretty good. But what else might I try?
Well, here is what I did this spring: Now this probably isn’t a brand new idea. I’m sure someone has done it before, but its new for me. (And maybe for you too.) I decided to make a mini-greenhouse WITHIN my greenhouse.
It was fantastically easy (it took all of ten minutes to build it) – and completely inexpensive – I simply used materials that were leftover from other projects. Here, let me show you…
I just took six planks (1x6s – about 30 inches long that were leftover from my fence project last fall), and tucked the bottoms inside my planting bed frame. Then I screwed the tops together and attached a long 1×2 (8 ft long) that served as the peak of my greenhouse. It was absolutely simple. Then I just took and threw over some plastic like this…
Then I ran some tests to see just how much of a difference it would make at night. Remember this is with NO additional heat.
On the night of May 2, the overnight temperature got down to 3.1° celsius outside in my garden. The greenhouse was a little warmer, going down only to 4.8° celsius. But inside my mini-greenhouse within my greenhouse, the temperature stayed up at 7.4° celsius. That’s 4.3° warmer than outside with NO extra heat. That might not seem like a large number, but that makes a significant difference in your growing season. That little, inexpensive “greenhouse within a greenhouse” project, according to the weather almanac, could have just added 9 days to my growing season – for FREE!
And of course, if I had wanted to heat that little greenhouse, it would be much cheaper to heat that little space than to heat the whole greenhouse. So maybe I’m over-reacting, but I think this is way cool and will doing this project again next year – nine days earlier!