Cold Frames –No Plants Should Begin Life Without One

Simple and Effective Home-Made Cold Frame

Cold frames are really nothing more than a simplified, self-contained smaller version of a green house. Regardless of whether you’re growing flowers or vegetables cold frames are probably the most useful garden structures you can have. A cold frames only heat source is the sun and as such, opening the lid by varying degrees is the only way to control internal temperatures. Some newer designs do include passive, solar-energy storage. Typically, cold frames range in height from 12 to 24 inches and will have either transparent or solid walls. Needless to say the lid is transparent.
A cold frame will allow you to:

As such, cold frames allow you to do a number of things in a relatively easy manner. Let’s face it, hardening off seedlings can be a real chore, but a cold frame makes it much easier. Furthermore, cold frames provide your plants with protection from strong winds; raise daytime and nighttime temperatures around your plants, and shelter frost sensitive vegetables or flowers. During sudden and unforeseen cold snaps cold frames can be covered with heavy cloth or burlap to provide additional protection and warmth.

While it’s possible to purchase cold frames, they can also be made fairly easily. In fact, a really simple cold frame could be made out of a wooden or plastic box with a transparent lid that can be raised. A more traditional method is to use an old glass window, build a timber framework that’s tall enough to clear the tallest plant you grow and then mount the window on top of this frame. You could even use concrete blocks or make a lightweight aluminium framework if you wished.

However, wooden cold frames are generally sturdier and definitely provide better insulation than metal ones. If you decide to make a wooden cold frame make sure you select a weather resistant wood such as western red cedar, cypress or even pressure-treated lumber. Plywood is another option although I wouldn’t recommend it unless you use a marine ply. When building or purchasing a cold frame keep in mind that some are constructed to grow plants in the box, while others are constructed to hold containers. It’s also a good idea to slope the lid of the frame from the back to the front.

Conventional cold frames are usually deigned to set level with, or just below the ground surface to provide protection and use the earth for additional insulation. Newer models tend to be constructed with a very high back and low front to help capture heat from the sun. They are insulated very well. Likewise, present day frames are often built to be completely above ground and covered in a plastic film. Regardless of the type you choose, your cold frames should be located in an area with a southern or south-easterly exposure to maximize solar radiation and with a slight slope to facilitate drainage. They should also be located in an area that is not subject to flooding. If you built or invested in an cold frame with a angled lid make sure that the highest part (back) of the frame faces the north and the lowest (front) part faxes the south.

As you can see cold frames can play a vital part in your gardening endeavors. They are relatively easy to build and if you’re not that handy with a hammer and nails they definitely make a long-term, very worthwhile, time saving investment. In addition to growing vegetables, cold frames are an excellent place to start new seeds in springtime or to care for cuttings in the fall and winter months of your favorite evergreen plants. In fact, the propagation of a wide variety of new plants can occur in a cold frame. If you have a short growing season a cold frame should allow you to plant seeds upwards of 2 months earlier than possible if you simply plant directly into your garden. Little wonder that cold frames are the most useful garden structures you can have.