Why Do I Need A Cold Frame?
A cold frame is used to help get an earlier start with cold weather seedlings in the early spring. The cold frame allows you to harden off those seedlings a week or two earlier than normal. You are trying to have your seedlings become as cold tolerant as possible in the event there is an unexpected freeze after the plants have gone into the ground. It is a handy tool but not essential to the beginning gardener.
Choosing A Cold Frame
There are dozens of designs for homemade cold frames as there are dozens of coldframes available commercially. In most cases, a beginning vegetable gardener will try one and within two years have another that works that way he or she wants. So start with a basic model.
In Yardener’s Toolshed we offer a number of coldframes sold via Amazon.com.
Setting Up A Cold Frame
You want your coldframe to face south or southeast. You can set the cold frame down on the surface of the soil. It helps to pile some straw or mulch around the edges to help insulate it a bit. Some folks in the fall will dig a six inch ditch in which to set the cold frame in the spring, giving it a bit more insulation.
Ideally you put your cold frame out at least two weeks before you plan to use it so the soil inside the cold frame can be thawed.
Using The Cold Frame
You set seedlings in the cold frame during the day and at first you bring them inside at night, usually an hour before sunset. As the soil temperatures and air temperatures approach being okay to plant cold weather seedlings into the garden, you can leave the seedlings in the frame over night. We always had an old quilt that we put over the cold frame and night since the plants did not need any light and any additional insulation was appreciated.
Thermometer Is Essential
You need to have a very good handle on the temperature inside your cold frame at all times. A minimum – maximum thermometer is the best way to go.
Ventilation – A closed cold frame can heat up very quickly on a sunny day. So usually by late morning, you will have to lift the cover a few inches and support it in some fashion to let that heat out still keeping the inside of the cold frame warm enough to help the seedlings grow. On cloudy days you usually can leave the cover closed.
When the cold weather seedlings are all planted in the garden, you can wait a few weeks and then use the cold frame to help harden off your warm weather seedlings such as tomatoes, peppers, and cukes.
In the summer you can open up the cold frame and cover it with shade cloth. It makes an ideal seed starting vehicle for starting seedlings while protection them from insects and inclement weather.