February 23, 2020

Cold Frames and Cover Crops Keep Garden Growing

Hairy vetch, Vicia villosa

Hairy vetch, Vicia villosa | Credit: Wikimedia Commons - Dawn Endico (CCA-SA 2.0 Generic)

• By Janine Pineo •

Snow in May does not a happy gardener make, but it hasn’t stopped me from getting a little jump on the vegetable garden.

One blustery day in late April, when I was desperate for some promise of spring, I wandered up to a small plot near the gardening shed and decided it was the perfect moment to set up my nearly new plastic cold frame.

I turned the soil, added some composted manure and secured the cold frame to the ground (it’s so light it tends to blow away).

When the temperature hit 24 degrees the next night, I checked the thermometer inside the cold frame. The 34-degree reading told me we were in business.

April 22 was planting day. After adding a milk jug filled with water as a heat source — solar charged, so to speak — I sowed spinach, Chinese cabbage, kale, brussels sprouts and six varieties of lettuce. These plants are a bit more tolerant of the cold and benefit from early plantings in spring. As an experiment, I poked in a few nasturtium seeds, which are definitely more tender.

One week later, it snowed. Fear kept me from the cold frame’s vicinity; I didn’t want to know.

The next day, I decided to tally up the damage.

Let’s just say spring had sprung.

Another week, another milk jug and yet another day of clouds spitting slush, and the nasturtiums appeared. If all continues to go well and I remember to vent the cold frame on sunny days — when the temperature can soar to 100 degrees — I expect to have greens a month earlier than usual and a nice display of nasturtiums in June. The brussels sprouts are a new vegetable for me, so who knows what they’ll do and when?

I am amazed I didn’t try gardening with a cold frame before now. Part of my hesitance was in finding a well-drained spot that was sunny and accessible; in fact, the plot in use now was planted with tulips and still has a few sprouting here and there.

The other part was that I didn’t want anything in the big vegetable garden because it disturbs my plowing and planting plans.

This year, however, it would disrupt more than that because the garden is the site for my first experimental crop of “green manure.”

This endeavor is meant to keep the soil in good health by providing food for hungry microorganisms, supplying nutrients for succeeding crops and fixing the soil with all-important nitrogen so necessary for happy plants.

With those noble thoughts in mind last October, I broadcast several pounds of winter rye and hairy vetch and raked them into the topsoil. Within a matter of days, the rye had sprouted, with the vetch not far behind.

The real test of my seed sowing came this spring: How much of either variety survived?

Given the ice sheets that covered the ground most of the winter, I was surprised to find just one casualty, the hairy vetch.

Vicia villosa has been touted as one of the best legumes for fixing nitrogen (which only legumes do) and, as the hardiest of annual legumes, the main reasons I bought it. My mistake may have been in the time of year I planted it — mid-October. Most seed sources recommend late summer to early fall planting, but I may not have given the hairy vetch long enough to establish strong roots before the ground froze. Then again, it may have been the winterlong blanket of ice.

My plan for the hairy vetch this year is to plant some of it a little earlier. As the potatoes are harvested, I’ll sow vetch in the growing patch of unused garden.

The winter rye, on the other hand, came through the winter mostly unscathed, although it hasn’t grown rapidly during this cold spring.

Winter rye, or Secale cereale, is considered the hardiest of the annual grasses and is recommended as a companion plant for hairy vetch because it provides support for the vetch’s vines. Winter rye protects the soil from erosion through the winter and improves the soil structure when plowed under in spring. It can be planted any time in the fall.

For gardeners with small plots where every inch counts, trying green manures can be as difficult as rotating crops. In my own garden, I try to keep as many of the plants protected from the frost for as long as possible each fall, which cuts down on the time available to establish the hardy green manures. Last fall, it meant some sections of the garden weren’t planted at all, but if my crop rotation works this year, those neglected sections will have a cold-season cover crop of hairy vetch and winter rye come autumn.

Those gardeners willing to give up a section of garden space during the summer can plant warm-season cover crops that are sown in spring and turned in during the summer months (cold season ones also will work). Many of these are available and include white and red clovers, buckwheat, oats, alfalfa, and fava beans.

First published in the Bangor Daily News in May 1997.