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Cold Frame

Posted by tinako on October 3, 2012

Not wanting to say goodbye to my garden in the fall, I’ve been building a cold frame to go onto my new raised bed.  You don’t at all need a raised bed for a cold frame, and as a matter of fact it might make the soil a little colder or dryer over the winter, but I was just sick of dealing with the clay here (back story).

My mom had a cold frame once, but I think she used it differently than I’m going to.  I think she just used it to give seedlings some extra protection and lengthen the tomato season a bit.

But I’m going for it.  I bought a book called Four Season Harvest by Eliot Coleman.  Here’s the web site for their farm.  This book is great, with interesting stories but also crammed with data, such as last planting dates based on your zone and what you’re covering your crops with.  They garden in Maine, one zone north of me, which makes me hopeful.  Even though nothing much grows in the middle of winter, they’re able to harvest year ’round.

So.  Based on the recommendations in the book, I went shopping.  There were several things I couldn’t find locally despite a lot of trying.  I bought some Phosphate Rock from Wayfair, 28 lbs. for $30 total.  All these prices include shipping.  I bought Greensand from Gardner’s Supply, 5 lbs. for about $15.  Those two are all the soil amendment they recommend beyond compost, and I figured I didn’t want to have the discouragement of bad results from poor soil my first year.  I’ll need 2.5 lbs. per season, probably twice a year.  I appreciated that both the recommended products were vegan so I didn’t have to figure out a substitute.  In looking at the local garden or hardware stores, all the fertilizer stuff is these mixes you don’t know what it is, or it’s all blood and bones and fish and stuff.  It struck me as “processed food” like muffin mixes and frozen burritos.  There’s always a problem or a mystery in a mix; just sell me the ingredients I want and let me do my own thing.  So I had to buy online.

I also bought an automatic venting arm from ACF Greenhouse Supply for $60.  This will lift up (open) the “light” (clear cover) on the cold frame when it gets too warm.  It works just by heat expansion, no electricity.  And I ordered some obscure seeds from Bountiful Gardens: $8.25 for a packet each of Claytonia (Miner’s Lettuce, Montia Perfoliata), Corn Salad (Mâche, Valerianella locusta), and Tatsoi.  All are really good at standing up to winter.  I put on the phosphate and greensand and planted the seeds as soon as they came in.

My cold frame waiting on the lawn.  It looks turquoise here but is actually a dark grey green.

My cold frame is almost done.  I followed the plan in the book.  The lumber is plain Douglas Fir; I bought a 16 foot 2 x 12 and an eight foot 2 x 8 and had Home Depot cut them down to two seven footers and two four footers, to match my raised bed.  I think that was $35.   My husband helped me cut the short side pieces so they slant from 12″ (back) down to 8″ (front).  And he helped me rip a scrap 2 x 4 into the three braces, and then cut gaps in the front and back for the braces to rest in.  Even though the book said not to bother, I painted it with leftover house trim paint both to make it last longer and to make it more heat absorbent.  And I screwed it all together this morning.  Ta-da!

Now for the lights (the clear covers).  The best is probably glass, and you make wooden frames for them.  But I wanted this project to be something doable in a short time period, so I planned on something simpler.  I kept my eye out for discarded storm windows, but no luck.  So I figured I’d use plexiglass, but Holy Smokes, the price!  Why is a 2 x 4 sheet of plastic over fifty bucks??  I was going to need four!  Plus nothing was the right size.  I’d already made the raised bed 7′ x 4’3″ (including the overlapping ends), and unfortunately 4′ is the max on most stuff, with 3′ being more common.  D’oh!  Hope was draining away in the back aisle of Lowes when a guy went whistling past me pushing a cart of those flimsy corrugated plastic roofing panels.  They were available in crystal-clear: eight footers were $20, twelve-footers $30!  Unfortunately the whistling customer had nabbed the last of what I needed, but I’ll forgive him.  They should be in soon.  I’ll post again when I have them and the venting arm installed.

4 Responses to “Cold Frame”

  1. Excellent post! Thanks for the details! I had been eying that same book and may now get it. The corrugated roofing panels are great – I had some over a small portion of my first house back in the UK and it worked like a charm for years. They can be pretty tough to cut though; have one of the folks at Home Depot cut the panel down to size for you (that way if it cracks it’s their loss!).

    • tinako said

      Thanks for the tip. We cut one on a radial arm saw. My husband thought to run masking tape such that we cut down the middle of it. Worked but maybe we were lucky. Or maybe that saw worked because it pushes down instead of up like a table saw. I had bought their last eight-footer thinking at the time I was spanning four feet (forgot the thickness of the front and back boards) and then cut it figuring I’d put a crosspiece at the top or bottom but today realized that wouldn’t work well, and my best bet is to go back and get a twelve footer, have them cut it to two 4’4″ lengths, and adhesive leftover scraps to the ends of the ones we already cut to four feet. I’m aiming to have the lights cover the wood so they protect it a bit.

      I thought you were someplace warm.

      • Good plan!

        You’re right! I transferred to Arizona with my last job but have lived several other places previously. Where I lived in England temperatures rarely dipped below freezing or above 75, so it was possible to grow a lot of things.

  2. […] VRG « Cold Frame […]

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