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DIY :: Strawbale Coldframe |
9 Comments |
| By Aaron Newton in Education, Green Living, How To | October 18, 2006 | ||
I recently overheard Albert Bates of The Farm make mention of using strawbale walls in greenhouses. Typically strawbale construction treats the straw walls with a lime and clay plaster to create a breathable, weather and bug resistant barrier. If not the bales rot. However when the bales begin to breakdown the process gives off heat. Mr. Bates leaves the strawbale greenhouse walls untreated so that they will decompose over the winter and give off heat to keep the plants warm. The following spring the partially decomposed walls are used to mulch the garden. I scaled down the idea a bit and built myself a strawbale cold frame. Here’s how to do it.
Step One: Stop and pick up old windows being discarded in someone’s trash. (Maybe this is a good time to replace the drafty windows in your very own home)
Step Two: Create a frame using the bales and partially fill it with soil and/or compost.
Step Three: Place your recycled windows over the frame and add plants.
Step Four: Use cat to test for structural integrity and quality of workmanship.
Be sure to prop open your windows during those last warm days of autumn. You don’t want to cook your plants. What an easy way to extend your growing season.
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Steve Balogh said,
What veggies will you continuing to grow into late fall?
aaron newton said,
I’ll be growing mostly lettuce and spinach in the cold frame. I have plans to experiment with a tomato to see if I can use the cold frame to produce those in the late fall or early winter. I also have cabbage, kale, collards, onions, garlic and potatoes growing outside. We can do that here in the south. I might put a couple of the veggies on that last list in the cold frame to see how they do.
michael said,
I would love to try this up here in Ithaca, but I’m not sure how well they would survive during those -14 nights. I wonder if integrating the windows with a ’snug’ fit might protect the plants a little more.
Another neat idea would be to plant some skunk cabbage in with the other plants. Skunk Cabbage is one of nature’s more interesting plant because it gives off heat. From an article,
“Skunk cabbages can bloom inside a snowbank and create their own ice caves. “You can break through the snow and look into these fantastic spaces,” Seymour says.
In experiments at air temperatures around 15°C, the inner core averaged some 9° higher. When the air temperature dropped to –15°C though, the fingerlike projections reached temperatures 30° higher than the air. “Some mammals can’t even do that well,” says Seymour.”
So maybe, some skunk cabbage mixed in would help regulate the inside temp of the bale during those really cold winter nights….
Douglas Barnes said,
This sounds like a great energy saver. The bales serve their purpose here, then are ready for early spring mulching. Great stuff!
Like in Ithica, we Canadians need to worry about cold weather. I don’t know how well things would do in the dead of winter, but in late fall/early spring, plastic could completely cover the bales and be tucked under the base of the bales. And the skunk cabbage idea sounds like a great one as well.
aaron newton said,
Black plastic on the inside of the cold frame can help raise the temperature as well. For those of you in really cold climates however this is more of a way to get started early or extend the season a bit. It might not be a way to successfully grow lettuce in Antarctica in the middle of winter. I suggest trying some form of season extension and then trying to push a little further into the cold season each year- an annual challenge.
Matt said,
Man, I love strawbales. I don’t know why they aren’t used for more things.
Albert Bates said,
I stumbled on this discussion later, in January, and would add my 2 cents.
We also use bales for cold frames and they work well, but I would caution you about a couple considerations. One is that they use up a lot of space, so greenhouses are one thing (we use 40 bales for ours and change out the wall every 2 yrs on avg, tho we have gone longer) but 6-bale coldframes are another.
A second thing is that in the process of decomposition the straw draws nitrogen from the soil, which it will eventually give back when applied as composted mulch, but when it is fresh and structural you need to be careful to protect growing plants nearby. Make sure you have plenty of good compost supplying nitrogen to the plants, and preferably some biodynamic preps or EM to activate the exchange.
And look for my new book, The Post Petroleum Survival Guide and Cookbook: Recipes for Changing Times, in a book store near you. Just asking at the counter enough times will mean they will stock it on the shelves and help me out. It has a recipe for building the straw greenhouse.
-albert
Jen said,
Fantastic ideas and advice all the way round! I think I’ll give it a go this year just to extend the season and then try to push limits a bit down the road.
Dirt Cheap Gardening » Growing through the winter without a budget said,
[...] Other frugal possibilities for protecting tender crops from frost are plastic soda bottles, and cold frames made with old windows and straw bales. [...]