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Those of us who live in colder climates are eager to start gardening every year. Fortunately, there is a way to start gardening early, without waiting for the snow to disappear in the spring: cold frame gardening.
Those of us who live in cold regions monitor snow levels daily to anticipate when we can start growing again and are obviously unimpressed when temperatures stay low instead of warming up.
But with a cold setting, we can’t start gardening until it’s technically even spring. Here’s how:
What is the difference between a cold spring or autumn setting?
The easiest way to describe a cold frame is that it’s basically a mini greenhouse. They absorb heat from the sun during the day and then retain it overnight.
These cold frames can be constructed of plastic or glass and are perfect for extending your growing season. Using cold frames in the fall allows you to continue growing things that might have died as the cool weather approaches.
On the other hand, cold spring frames can be used to give you more growing time in early spring. It’s the same structure, but what differs is how you use them.
You may have seen cold frames in your neighbors yards and not recognized them for what they were. Usually they look like raised beds with lids on them. In fact, many people confuse them with compost or storage bins.
In my case, my cold frames are recycled IKEA bookcases with glass doors. I found them on the side of the road years ago and have been using them in my garden ever since. You can buy pre-made frames at a garden center or DIY them with materials you already have at home. Whichever way you go, they’re perfect for getting your garden started early.
You can either grow cold hardy crops in these frames or use them to harden off seedlings. I’ve done both and can’t recommend the process highly enough.
Not only does this allow you to grow more food most of the year, but it will help kick start the growing season. Generally, using a cold frame will allow you to grow and harden seedlings at least a month earlier than usual.
How to set up a cold spring frame
Two factors will determine which cold frame type(s) is best for you. One is space and the other is orientation.
Location is so important!
For example, the best location for a cold frame is facing south. This is because it will be exposed to the most light during the day.
Additionally, you will need to consider drainage, wind, and other factors. Look around for large tree branches that could fall in strong winds. The last thing you need is to have to pick up the broken glass of your lettuce after a storm.
What about water runoff? If you have a lot of snow around, it will melt. Try to avoid placing your cold frame in a low area that will collect melt water. This could damage your plants and swell your frame.
The size and shape
In terms of size, you will need to create a frame large enough to grow food, but not large enough to overshadow your garden. It should be small enough to comfortably reach, but not too bulky for one person to handle solo.
My preferred size for a cold frame is about 2 feet wide by 2 feet deep and about 6 feet long. If my frame is longer than 3 feet, I create at least two hinged glass tops for them. These smaller doors are much easier to lift and open than the longer ones.
The top can be tilted to help guide water and snow. If you tilt the structure, make sure that the bottom side is the side that faces the most sun. This way you increase the amount of sun the plants will receive.
The materials will depend on what you have available and how much you want to spend on your frame.
For example, I mentioned my hacked IKEA bookcase earlier, but I’ve also built some cool frames out of salvaged materials. Our porch was redone last summer and the 2×4 inch boards were great for reusing in cold frames, raised beds, etc.
Now remember you need something transparent or translucent to let the light in. We are lucky to have many abandoned farms in the area. As a result, we were able to salvage old windows from the timber at zero cost.
You can also find them at thrift stores or on buy/swap websites. Alternatively, you can use Plexiglas or greenhouse-grade plastic sheeting.
Draining and ventilation
I know many people who have accidentally drowned, smothered, or baked plants in their cold frames. Better to avoid doing any of the above things.
If you are using a pre-made box frame, be sure to drill drainage holes in the bottom. Otherwise, leave the bottom open. In terms of ventilation, you can either drill 1/2 inch holes in the sides, up, or open the frames regularly. This will allow trapped moisture to evaporate, while increasing airflow.
The type of flooring used for a cold frame is the same for any raised bed. Your best option is potting soil with extra drainage and water retention amendments. I like to use organic potting soil and then work with additional perlite, vermiculite and coir.
Spread a 2-inch layer of gravel or pebbles for drainage. Then add a few handfuls of twigs and straw to a depth of about 4 inches, followed by your potting soil. The twigs will add extra aeration and drainage, while the straw will help insulate the roots from surrounding cold.
Best Plants for Cold Gardening
Since spring temperatures will fluctuate quite a bit (and may stay cold for some time to come), your best options are short-season, cold-hardy species. These tolerate the cold better than the tropical varieties.
Some of the best options for your cold frame will include:
Just because a cold frame regains warmth doesn’t mean it won’t freeze. Depending on where you live, spring temperatures can still drop steadily. For example, here in Quebec, it can snow until June. As a result, your early gardening efforts could end up stalling.
If you started planting seedlings indoors and are hardening them off in your cold frame, expect them to be at least 5 inches tall. This should make them a bit more resilient in the event of a sudden cold snap.
Beware of overhanging icicles or anything else that could damage your frame. Also, try to keep large pets or livestock away from them. The plants inside will be tender and will not tolerate being trampled by your Pyrenees. Also, your pets can be seriously injured if they cut themselves while jumping through the glass coverings.
If you have noisy animals (watching you, goats), consider plexiglass instead of regular glass. It will be less likely to break if they jump on the frames.
Honestly, you can’t go wrong with a spring-loaded cold frame. In fact, having several for various purposes is absolutely ideal. While one incubates peas and early greens, another might harden off early tomato or pepper plants.
You can propagate cuttings of medicinal herbs to get a head start on this year’s medicine, or protect young berry bushes until they are large enough to transplant elsewhere.
Considering how easy they are to put together, there’s really no downside to having several at once. They’re great for utilizing space that would otherwise be wasted, and you’ll have more abundant, healthier plants as a result. You can’t lose here.
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