I am beginning to plan this year's seed starting schedule. I plan to re-build a basement light stand set-up similar to the one I used to have. Many of those seedlings will then move out to my hoop house, but in March, it sometimes still gets too cold in there. My solution? I will put my cold frames inside the hoop house for extra protection.
This will be done in a similar way that I used to put seedlings in the cold frame out in the garden in April and May. Thinking about my cold frames reminded me that I should write about the benefits of cold frames.
Not every gardener can have a greenhouse, but they all should utilize at least one cold frame. I consider the cold frame the single best garden investment, but many people don't know about them.
I want to start with showing you one of my basic cold frames.
So what exactly is a coldframe and why should you have one?
A cold frame is essentially a bottomless box with a covering of glass or clear plastic sheeting. These coverings are called "lights" because they collect the warm sunshine to heat up the plants contained inside the frame. This "box" can be placed directly over a portion of your garden bed to protect plants that are growing in the ground. You also can simply use your cold frame to place potted plants inside. The "lights" are constructed on the top of the frame at an angle - usually somewhere between a slight angle to a 45 degree angle, facing south to maximize mid-winter sun.
I consider a cold frame the gardener's single best investment because it enables you to extend the growing season for several months. In many areas, a cold frame will aid you in growing cold-season greens all winter long. The more months I can provide my family with healthy organic vegetables, the more money I save!
The cold frame is not a new invention. It dates back to the beginning of cultivated farming. It is very versatile because you can build it to suit your space and your needs. It can be any length as long as you can get the tops to fit. Many times you can construct one out of recycled or reclaimed materials such as old storm windows. My first cold frame was made from an old shower door. I do have to pause here to issue a warning however. Keep in mind that if you use glass as the "lights" that it can become dangerous if someone steps or falls onto it. I switched to using greenhouse style plastic sheeting when I had small children "helping" in the garden. Always remember, safety first.
So how does the cold frame work?
It protects plants from wind and freezing. When the lid is closed, it creates a micro-climate with the temperature being higher than the outside temperature. Granted, the difference may only be 5 or 10 degrees different in the winter, but that is significant when you also cut down the wind and the moisture that leads to freezing.
So what are the primary uses for a cold frame?
- In the spring, you can start cool-season vegetables earlier.
- In the fall, you can keep cool season crops growing longer.
- In winter, you can keep root vegetables and cold tolerant greens from freezing. This gives you an extended harvest!
- In the spring you can use your cold frame to harden off flower and vegetable plants that you started from seed indoors. This is another way to save money. You don't have to buy your plants from a garden center.
- In spring and early summer, your cold frame can be your nursery for growing new seedlings.
If cold frames are so good, why doesn't everyone use them?
Mainly I would have to say it is because they haven't fully considered the benefit of having them in the garden. Another reason could be because of the extra work it takes. Yes, they do require some extra work. The drawback with using coldframes is that you have to constantly be aware of the weather outside. A coldframe needs to be vented if there is direct sunshine on it or if the temperature significantly rises. The power that we rely on to keep the veggies warm can quickly become powerful enough to cook those veggies.
This is not as much a problem in the middle of winter, but you have to be careful in the spring and fall. If you can't be ready to open or close the frame based on the changing weather, you can purchase an Automatic Vent Opener that will do it for you. I would love to have one, but we have always watched to venting needs ourselves. I do admit however that in the Spring I am always wondering how the plants in the cold frame are doing. If we get an unusually hot and sunny day, we take the top off entirely. It can actually be fun trying to figure out what the weather will do. The venting requirements vary depending upon the season. On most days there are no problems at all. Even when it gets tricky, the benefits still outweigh the hassles.
I strongly encourage you to use a cold frame to help you grow more food for an extended period. If you have used them in the past, but haven't lately - now is a good time to re-consider them. If you have never used them before - now is a good time to make yourself a small frame. You can see a very simple design on my post Step by Step How to build a Cold Frame.
If you are like me and it is winter where you are, building a coldframe while it is snowing outside will make you almost forget the cold and long for warm gardening ahead!