Gardening

With May now under way, the season for cold frame gardening is drawing to a close. I keep my peppers and tomatoes warm on colder nights by closing the glass, but more often than not the glass stays completely off to allow unexpected thunderstorms to water the plants. More and more, the frames start getting in the way, though they are still very much appreciated when the threat of frost is issued on the radio.

By the middle of the month I am eager to get the cold frames off of my solanums and onto my cucurbits. I find that winter squash and melons especially enjoy the extra heat for germination and good growth until June’s blazing temperatures make the cold frames altogether superfluous. In spite of the cold frame, I will still put some hooped row covers over the young plants to slow down the squash bugs and cucumber beetles. It is nice to have the boxes hide the otherwise unsightly white gashes in the landscape.

By the end of May it is time to really start finding an out-of-the-way home for my cold frames. Not too out of the way, however, since I have found that cold frames make suitable solar dryers for fruits and vegetables. Sliced tomatoes, laid on screens, will dry in two or three sunny days! The heat trapped by the glass pumps the moisture right out of the vented crack I leave at the top. The glass also acts as a convenient barrier to rain and dew; no need to ever transfer the drying racks indoors.

This year I may even try curing my onions and garlic in the cold frames. It will probably be necessary to find something to shade the bulbs from direct sunlight. With careful monitoring, I hope that the cold frame might simulate the conditions of the awkward-to-reach attic where I usually cure my alliums.

Last year I tried to cure our sweet potatoes in the cold frames (they need warm humid conditions to encourage sweetening and storability) and had moderate success. I may have removed them from the frames a little too early, however, for the tubers never got their full flavor.

Before concluding this series of articles on spring cold frame gardening, I will share my revised timeline for next year’s sowings and plantings as a brief review and reference guide.

January (early)–Start Crucifers (Broccoli, Cauliflower, Cabbage)and lettuce seedlings. / Sow Salad Greens direct in cold frames.

January (middle)–Start Solanums (Peppers and Tomatoes) & Basil.

February (early)–Prick out Crucifers into small pots and put in an insulated seedling cold frame. / Sow Peas and root crops direct in cold frames.

February (middle)–Prick out Solanums into small pots.

February (late)–Re-pot Crucifers into larger pots.

March (middle)–Plant out Crucifers into cold frames. / Re-pot Solanums into larger pots.

March (late)–Sow Cucumbers and Summer Squash in large pots.

April (middle)–Plant out Solanums, Cucumbers and Summer Squash into cold frames. / Sow Melons and Winter Squash in large pots.

May (early)–Plant out Melons and Winter Squash into cold frames. / Sow more Melons and Winter Squash direct in cold frames.

Similar magic can be had by extending the season for fall crops with cold frames. This makes year-round gardening possible in our county. Quite the trick, especially if you can manage to do so without burning out!

By starting a late crop of tomatoes in June, I am able to get fruits to mature in cold frames in October and November. Special keeping varieties, like Burpee’s “Longkeeper,” will continue to ripen in storage well into January. A well-timed crop of lettuce will head up and be protected from the first heavy frosts of October and November, while baby salad greens can be direct seeded almost anytime, sometimes surviving even the coldest nights of winter.

Another nice addition to the winter cold frame garden is cooking greens like kale and spinach. These will provide infrequent meals throughout the winter and will then produce abundantly in March and April when warmer weather arrives. This past winter I learned that beets make a hardier substitute for chard in the cold frame. They are really the same vegetable, genetically, with the added bonus of having their roots, as well as their tops, be edible!

I hope that you have enjoyed and will benefit from the information shared in these articles, and that someday you will share with me your own cold frame experiences and discoveries.

Happy Gardening!

Jonathan weeding cold frame

April is a busy and exciting time, especially when gardening with cold frames. While convincing signs of spring are just beginning to emerge outdoors, summer is well under way under the glass. With temperatures consistently 70° or above by day, and the danger of frost essentially gone, almost anything can be grown in the frames by mid April.

By early April, my broccoli and cauliflower plants will be pushing against the glass, exposing them to frost and sunburn. To avoid this, I have built extension boxes that essentially raise the height of my cold frames. By the middle of April, those plants are getting little benefit from the extra heat and protection of the cold frames and I carefully find the proper timing to remove the frames and let the young plants fend for themselves.

I eagerly look forward to the day when I plant out my tomatoes, peppers, and basil into the freed-up cold frames from my liberated crucifers. I again aim for the middle of a warm spell. Started in January, the tomatoes are usually bursting out of their pots, some of them with flowers blooming.

I will plant those tomatoes as deep as I can to encourage extra rooting from the stem, making sure to leave the flowers above ground for the possibility of some early fruits in May. Since determinate varieties of tomatoes have a bushing habit and do not vine like their indeterminate cousins, my cold frame plants don’t need trellising. However, the plants do have a tendency to flop over, so to prevent the fruit rot this encourages I have learned to put a hoop tunnel made from fencing for the plants to grow through, giving extra support for the luscious, pendant fruits.

This year I am growing twice as many cold frame peppers as last year. If you have ever struggled, as I have, with getting peppers to flower and fruit in the summer, cold frames may be your solution. I probably got more fruit, in one quarter the area, from my cold frame peppers than I did from the main-crop plants I started outdoors, all due to one month of extra, early protection.

The early-started plants, moreover, were spread out through the whole season and had plenty of time and fruit for early red peppers, unlike the regular plants that were mostly foliage all summer, with an excess of unripe fruits just before frost. Once again, a good example of how concentrated energy and attention can pay for itself multifold!

If you don’t have early tomatoes or peppers to plant, don’t fret. It is still not too late to start some fast-growing cucumbers and summer squash in pots to be planted out later this month. Kept in a warm, bright location, the large seeds will germinate quickly and will need to be planted out into cold frames before the roots crowd the pot, since cucurbits are not that fond of being transplanted in the first place. In fact, by mid April you could even direct seed those plants right into a free cold frame if you prefer.

Being such powerful tools of growth and transformation, cold frames do not come without certain costs and dangers. They will need constant monitoring, especially at first while getting the hang of it. Expect to learn the hard way, since all it takes is a couple of hours of midday sun without venting to find the foliage of your tender plants burnt to a crisp. Transpiration is also extreme in the greenhouse environment, so frequent watering is necessary. Opening the cold frames completely for soaking rains is ideal.

If you do find your plants burnt or withering, don’t give up. I have been amazed at how quickly well-rooted plants (much like their human counterparts) can regenerate themselves. Nevertheless, I hang onto any extra seedlings I have, in order to fill in holes caused by pests or problems. There is nothing more satisfying than a full house of plants.

It is also helpful to have family, friends, and neighbors who are supportive of your cold frame initiative. Otherwise, being tied down to cold frame maintenance will start feeling like a confining chore and not like the labor of love it was meant to be. Those early cauliflowers and tomatoes make flavorful rewards and compensation for the hard work of yourself and others.

Moreover, any mistakes and shortcomings will ripen into lessons for next year’s experiments. Already this year I have regretted my early broccoli transplant that left my tender kale and chard unsheltered. Shocked by a sudden drop in nighttime temperature, they lost most of their foliage to frost and windburn and have taken three weeks to recover. In the May article, I will share my revised timeline for next year’s sowings and plantings. Until then, happy gardening!

Jonathan moving cold frame

As the spring equinox draws near, the cold frame gardener finds it easy to stay busy. With greens, peas, and root crops already sprouted, it is a good time to look for holes in the rows of plants (often due to rodents) to re-sow. Be sure to keep the frames vented on sunny days and well watered. You can even remove the glazing entirely to catch any warm spring rains.

Now that your confidence in cold frames is swelling, you can begin to focus on your transplant seedlings. Assuming that you have already started your broccoli, lettuce, tomatoes, and other such delights, it is important to get these seedlings into containers in order to sustain the seedlings until transplant time. I tend to be short on space and will use small, 2 1/2″ pots with the option of re-potting into larger ones as needed. Though this is more work, I find it easier to keep a smaller area well protected and watered when the weather outdoors is still harsh.

Most seedlings need to be pricked out into pots about two weeks after germination, once true leaves have emerged and before the seedlings get too crowded and leggy. If (like me) you are without a greenhouse, your potted seedlings can get by with a cold frame that is well insulated with straw or leaves. A blanket and tarp also help reduce heat loss through the glazing on cold nights.

It is important to keep a watchful eye on the seedlings after they have been transplanted (bare rooted) into pots. Shading from direct sunlight is often necessary for the first few days. Lacking the buffer of a large soil mass, potted seedlings tend to be even more sensitive to extremes. Venting the cold frame is often necessary by mid-morning on sunny days in the 50’s. And all it takes is one frozen night to permanently shock a potted seedling’s root system.

Caring for seedlings in a cold frame in March is a delicate and demanding art. Guided only by a thermometer, observation, and intuition, the dedicated gardener must ensure that the seedlings survive and ultimately thrive through the extremes of temperamental Spring weather.

Why does the eager cold frame gardener bother to take on such a challenging task? Of course, there is the obvious explanation of early produce. What a shame to wait until July or even August for tomatoes when June and often May are already sunny and hot.

Another reason for all the labor that goes into extending the growing season is that it reduces the need for labor- intensive food preserving. Since the quality and nutritional value of fresh produce is incomparable, the cold frame gardener is doubly rewarded.

Moreover, cold frames reduce the temptation to purchase non-local produce whose real environmental cost is hidden. And any surplus from the cold frames can be bartered or sold to neighbors for a premium.

But there are other, less tangible benefits as well. I have found plants to be good reflections of our spiritual selves, with many parallels between caring for early seedlings and caring for one’s soul. Living in the somewhat protective environment of this community and this county, I often feel like a sheltered seedling. The warmth coaxes me to grow and evolve, but there is also the risk of being blasted by extreme conditions or negligent care. Like seedlings, we must trust in the coming season. When we are transplanted into the garden, and our roots are finally free to stretch deep into the Earth, our ripening fruit shall serve as signs of what is possible for the human species.

So by mid to late March you can begin to think about transplanting your hardier plants into cold frame protected garden soil where they ultimately belong. One of the main benefits of having individually potted seedlings is that there is virtually no transplant shock. Nevertheless, it is helpful to time the transplant during a period of mild weather and to warm the soil by moving the cold frames into place a few days prior to transplanting. You should hopefully be able to safely steal cold frames from the peas, root crops, and greens that you sowed last month.

Because my cold frames are precious real estate, I tend to pack them with plants that use extra compost and premium garden soil. When transplanting, I will crowd broccoli and cauliflower in staggered rows with 15″ spacing, even squeezing in some quick-growing lettuce in spare corners, to be harvested before their larger neighbors take over.

Less hardier crops like tomatoes, peppers, and basil will need to remain potted a month longer, until the cold frame housing your broccoli and lettuce frees up in April. The tomatoes especially may need quart-size pots before long to tide them over until then. More on the care of these warm weather crops and the maturing plants in your cold frames next month.