Cold Frame Gardening 1: February

Jonathan watering coldframes
Jonathan watering coldframes

For several years now I have been experimenting with growing seedlings and plants in cold frames at Light Morning. The successes never cease to amaze me. From salads all winter to dried tomatoes in the summer, cold frames have kept my thumbs green (and sometimes shades of blue in January!) twelve months of the year.

People are sometimes surprised to find that after more than twenty-five years of intense gardening energy here, we still do not have a greenhouse. While I would like to have a greenhouse someday, I would not do without my cold frames for even a season. Not only are cold frames much cheaper and easier to build than greenhouses, they tend to be much more portable and therefore, in my opinion, more versatile.

It is this quality of mobility that has allowed me to develop a succession system that extends the season of various crops by about a month in the spring and in the fall. By successively rotating the cold frames to different beds and new crops (from hardier to more tender, and from January to June), I am able to keep virtually  four times the area of plants protected in one season than if using a permanent greenhouse structure.

In order to verify all this for yourself, of course, you’ll need to build a cold frame. We use a variation of Elliot Coleman’s design. (See his books, The New Organic Grower and Four Season Harvest, for ideas.)  I suggest first finding a cheap source of glazing material and designing your cold frame around them. We were fortunately gifted with some oversized tempered glass doors (61/2’ by 31/2’) that have proved to be excellent though heavy. I can barely manage carrying a single pane by myself. Sashes, though easy to come by, are headaches in my opinion, due to the ease of breakage and the annoyance and potential hazards of chipped paint. Be sure to design some thorough way of strapping down your glazing. (Rubber bungees work well.)  I have regretfully shattered several panes due to insufficient protection from strong winds.

I’ll assume that you already have a cold frame or two. (We have about a dozen. Watch out–they’re addictive!) Now let’s get out in the garden. Next time there is one of those mid-winter thaws you should be ready to plant some greens. In fact, I never stop sowing.  I plant successions of salad greens throughout the winter whenever I can (about once a month). Be sure the ground is well thawed, since working frozen ground damages soil structure.

All it takes is a little sunny weather to heat up the soil sufficiently for germination. I find things germinate in about twice the time they would under more ideal conditions. In the winter I sow thick stands of tightly-spaced rows of lettuce mixes and other mesclun-type greens. Harvested as baby greens, they are ready in about two months (also about twice the usual). I have found that the smaller plants are much less susceptible to freeze damage than mature heads. If you harvest an inch above the crown you should get three to four cuttings. This winter I am alternating rows of spinach with other greens so that the spinach can take over in March, once the salad greens are spent.

I actually hope to also start my first root crops and peas the next time I am able. I plant both dwarf and tall varieties of peas at the back of the cold frame to be trellised later, once the cold frame moves onto other crops. That leaves plenty of room for carrots, beets, and whatever else you like toward the front of the frame. You should get your first tender samplings of these by May if they’re sown by early February. We start our onion seedlings at about this time, too, and transplant them into garden beds in April.

As I mentioned at the beginning, this is also the time I start my early tomatoes, as well as broccoli, cauliflower, cabbage, head lettuce, peppers, eggplants, and basil. Germinated indoors, these will eventually get potted up and moved to a cold frame (insulated with hay and blankets) in March. There they continue to grow until warmer weather, when more cold frame space frees up for their protection. I will describe how this works next month. For now, if you want those early fruits, get the seeds started!

I strongly recommend the Territorial Seed Company catalogue as a good source for certain seeds and for information on over-wintering crops in general. They even have a separate winter gardening catalogue. They have been a wonderful source for early determinate tomatoes (often bred by Dr. James Baggett, my hero), which are perfect for cold frames. My favorite is “Siletz,” though the more commonly available “Oregon Spring” is also good. This year I am trying a new Baggett creation called “Legend.” It’s supposed to be the first late-blight resistant tomato. Both are open-pollinated to boot!

Finally, I cannot conclude without saying a few good words about spinach. Whether you have a cold frame or not, this is a crop that all gardeners in this area should grow. For the past two years we have been eating fresh spinach salads from plants growing in the garden without any protection! Started in September, spinach gets to mature just enough to hold plenty of delicious sugary sweet leaves to fill bowlfuls of salad throughout the winter.

Though some leaves may get slightly discolored and limp with extreme temperatures, it invariably rebounds with warmer weather and will even grow some, given a string of mild days. Come March, these same plants will go crazy before bolting and will give you many pots of steamed greens.

Well, that’s all for now. Happy gardening!