The Magic of Coldframes

If you garden in a cold-weather climate, one of the nicest things to have this time of year is a coldframe.  In many iterations, a coldframe is essentially a miniature greenhouse used to "harden off" seedlings before planting into the ground or to extend the growing season.  Commercial kits are available, but in our opinion it's better to scavenge the materials and design your own to get the most flexibility at the lowest cost (and prevent those old windows from going to the landfill!)  We were originally going to use this post as an excuse to show off our developing Google Sketchup skills, but then we realized that we designed the whole thing around the particular windows we scavenged, the dimensions of our front deck, the height of the window looking over the front deck, and the pots we wanted to fit inside.  That is to say, the highly specific dimensions we used for our situation would likely be completely arbitrary for yours.  Instead, we decided to show you our design and point out a couple design features we incorporated to facilitate moving big (heavy) pots in and out of the coldframe, as well as a few lessons we learned that we'll improve the next time around.

Here it is all brand-spankin' new and closed up early during its first spring.  We scavenged the windows for free from Craigslist, although admittedly the wood and hardware is new. We didn't worry too much about the angle of the roof relative to the sun; we just wanted to make sure the back wall fit under the window in the house and the front wall had enough room for our potted plants.  If you look close, there's a sprig of swiss chard poking up just left of center.

And here's Katie a minute later, holding it open to show all it's degrees of articulation.  The 'barn doors' on the front make it a lot easier to get big pots, like whiskey half-barrels, in and out without having to lift them up over the front.  Note that the 'Z' piece has it's low end on the same side as the hinges--that makes the door less likely to sag as time goes on.  If you want to make doors on the front, it will help to have a flat space in front of the coldframe.  Also, don't worry--Katie didn't stand there all summer.  Normally we prop the windows open with sticks on warmer days, although there are probably better ways to vent it (see below).

A couple months later it's looking a little fuller.  The two whiskey half-barrels fit nicely across the back. When the weather gets nice enough that the windows are no longer needed, we take them off and tuck them underneath.  If the coldframe is going under a roof line, having the row of windows in the back can help disperse the water running off during a heavy rain.  The whiskey barrels have potatoes (left) and garlic (right) in them.  Note that the window by the potatoes has a crack in it--we found out the hard way that it's important to have a secure way to hold the windows open.  Just propping the windows open with sticks doesn't really hold them against strong winds or clumsy Jakes.  We're planning to attach an 'adjustable' stick to the 'removable' windows that we can secure to the frame between the 'removable' and 'fixed' windows.  We'll write it about soon.

When we harvested the potatoes in the fall, we planted some swiss chard seedlings in their place.  As an experiment, we also had some swiss chard growing in the square foot garden without protection from the coldframe.  This picture is from the following March (a few weeks ago).  The chard outside the coldframe froze off, but the stuff inside is flourishing.  Fresh greens from the deck in March?  Yes, please!

Some of the garlic we didn't eat as greens last year also over-wintered well and is looking quite robust.  (We didn't try any garlic outside, but if he had, it definitely wouldn't be this far along.)  We're looking forward to some luscious bulbs in a few weeks!  We also had some potted strawberries that came through the winter in the coldframe, which we moved outside last week.

One thing we should have done right away is to protect the wood on the coldframe with some kind of finish or paint.  We didn't get around to it, and although it makes this picture of the chard we harvested last week look extra rustic, we'll probably have to replace the wood on the coldframe sooner because of it.

Do you have a coldframe?  Did you incorporate any unique design features?  Tell us about it in the comments section below!