What’s a die-hard gardener to do in the middle of winter, when the ground, outside, is still too cold to plant anything? Start growing in a cold frame!
A cold frame is used to protect young plants from the outside elements and cold weather. It functions like a mini-greenhouse and is a great way to get a head start on or extend the growing season.
A couple of weeks ago, I started some seeds of cool weather vegetables: broccoli, cauliflower, cabbage, and kale.
Some have developed their second set of leaves, and because they are starting to take up too much room indoors, I’ve decided to re-pot them into larger containers and take them outside to continue growing inside the safety of a cold frame.
Cold frames are very easy and inexpensive to construct. All you need is some scrap lumber, nails, old windows, and a little effort to put it together. I’m always on the lookout for free scrap lumber and windows and pick them up every opportunity I get, and store them in my backyard…I don’t think you can ever have too many cold frames in the garden!
The first step in construction is to build the wooden frame. A simple box is all that’s needed. It doesn’t even need a floor.
Once it’s been constructed, place it into an area of the garden where it’s sure to capture a lot of sun. Typically, cold frames are placed on the south side of buildings, where they’ll get plenty of sun and can also take advantage of the radiant heat coming off of the building.
I’ve placed mine out in the open, at the end of one of my garden rows, away from any trees or other large structures that might block the sun. At the bottom of the frame, I’ve shoveled in some fresh chicken manure and kitchen scraps. As they break down, and decay, they’ll give off heat, helping the plants stay a little warmer at night.
On top of the compost, I added a layer of almond hulls for extra insulation.
For windows, I’m using an old cabinet door, with a missing middle pane (which is actually quite helpful, as you’ll see in a moment), and another, smaller framed window that fits perfectly over the missing window section.
Now, the cold frame is ready for the plants! I snuggle them into the almond hulls, and place the windows on top…
Many cold frame kits or plans are constructed to allow for the window to slope towards the south, so that it can capture the maximum amount of sun. Mine lays completely flat, and I think it works just fine.
Now back to that middle window section that you may have been wondering about…Because the middle window of the original door is missing, when it’s warm outside, I simply lay the other window, on top, at an angle. This allows fresh, cool air to enter into the frame, keeping the plants from over heating, while still protecting the tender plants from any harsh winds that may be swirling about. When the temperature drops, I simply move the window back into place and leave it until the outside temperature climbs back up again.
As the plants grow taller, I’ll need to transfer them into another, larger, cold frame.
I love using cold frames to get a head start on my spring garden, growing seedlings that will later be transplanted into open ground. It’s another great way for a die-hard gardener to stay busy, and continue gardening, even in the dead of winter.