Spring and fall are seasons where gardeners worry about protecting tender plants from frost or inclement weather. Very often, a coldframe is the answer. Coldframes may be simple or elaborate, and this article includes links to information about structures across the spectrum, but no matter what they look like or how they are made, they all protect plants from a few degrees of excess cold, from wind, and from pelting rain or hail or heaven forbid that last freak spring snow we call the "onion snow".
Now, let's be very clear on one thing. COLDframes are called COLDframes because they are not heated. A coldframe with heat would be called a HOTbed; we'll look at those later in this article. And for the record, a greenhouse can be either cool or warm, but that is another story and conservatories are not in the scope of this article, either.
So let's accept that you'll need a coldframe whether you are contemplating starting flowers and vegetables from seeds or concentrating mainly on producing some nice sturdy vegetable transplants. Those tender baby plants need to go into a coldframe to "harden off" or become "conditioned" prior to being planted out in the garden.
(In case you are wondering which vegetables are easy to start indoors and will need that trip through the coldframe and which vegetables are not usually started inside, here's a handy vegetable starting/transplanting ease chart.) For instance, stringbean seeds are usually planted in the ground in the garden where they are to grow rather than started early indoors.
Coldframes (and hotbeds) can also be used for some serious season extending, for instance to grow lettuce and other extra early crops outside the normal season.
And just in case you need still more justification for why you need a coldframe, it can be used to force those spring blooming bulbs, too.
Home coldframes can be very simple as in this photo, or even simpler -- and eminently portable -- as in this coldframe made from a recycled tire. (Don't miss out on some more fun with old tires).
