Let There Be Light! Winter Gardening in Somerville

by Kristin DelViscio

Farming through all four seasons requires little more than planning ahead. The faint of heart might be discouraged by Somerville’s average winter low temperature (22 degrees Fahrenheit, putting us in plant hardiness zone 6.) Not the Groundwork Somerville Green Team! They took winter by the horns and constructed low tunnel homemade hoop houses over three raised beds in an effort to extend season production through the coldest months of the year. Even though our first frost is quickly approaching, it hasn’t yet arrived: if you haven’t thought about season extension, it’s not too late! With still a week left, you may want to “cover crop” your garden, so pick a seed and sow.

The best cover crop for this region, this late in the season, is rye. Winter rye, in particular, is hearty with an extensive root system. It can grow in soils with a low pH and can withstand cool temperatures. Looking out on rye’s bright green leaves will definitely help keep the winter blues away as well. On the farm, the Green Team scattered rye throughout ten raised beds in addition to planting spinach, mâche, and kale. We’ll try to sneak in a few rows of carrots too.

Two challenges that we face at the South Street Farm include the amount of sunlight and a source of easily accessible water. Although the lot that we grow on is large (416 sq ft) sunlight reaches 4 of the 13 raised beds throughout the day, as a tall metal corrugated fence borders the garden. Neither obstacle is insurmountable, and we’re working around them.

We rely on sunlight, of course, to make the crops grow, but in the winter it’s also a crucial source of heat! By locating the sunniest spots- the spots that collect the most light and heat- we can harness this energy with row cover above the beds. The row cover that we’re using is called Agribon 19, which is made of spun bonded polypropylene fabric. This particular fabric allows 85% of light to penetrate the cloth. Almost ideal, the cloth also provides protection from wind and frost, allowing temperatures within the beds to sustain seedlings, transplants, and soon-to-be full grown crops.

After draping the cloth over the beds (making sure to cut a few extra feet on each end of the bed in order to ensure full coverage) pull the cloth taut and secure it. Use a pipe clip, clothespin- or any other tool you find appropriate for attaching cloth to the hoop frame of the hoop house- tautness is key to preventing cloth collapse from rain or snow. We’ll also add a layer of plastic sheeting before the first snow, and that might be a good idea for you. A single layer of plastic allows light to penetrate while providing a warm blanket for our plants. A film of moisture often coats the underside surface of the plastic row cover. This moisture reflects back heat waves radiating from the soil during the day, which helps to keep the air within the house warmer at night.

As for a source of water? We have great neighbors! We use a tap across the street which requires extending a series of hoses over a road. Considering that the our green farm was once a post-industrial brown field, having access to any water allows this farm to be possible. However, to mitigate any water dependence, the Green Team has already built a rain roof catchment system right on the lot with two full barrels to supplement our current water situation. In any case, winter rye doesn’t require much water after germination. Our winter crops won’t need as much water as their summer counterparts, and we won’t give them as much- thereby avoiding any chance of mildew.

The crops we’re growing this winter have proven to be vigorous and delicious. Two leafy greens in particular that can withstand and even thrive in cooler temperatures are spinach and mâche. Spinach is particularly unique because the sugars within the leaves act as natural antifreeze. Eliot Coleman, renowned winter farmer, has shown that sweet carrots, baby leaf mesclun mixes, spinach, mâche, and leeks (to name just a few) are reliable winter farming crops. If all goes well, come early spring time, when grocery stores are devoid of local leafy greens, the Green Team will be able to proudly reap their harvests.

To supplement our hoop houses, the Green Team has begun planning and construction of cold frames! Out of reclaimed aluminum framed storm windows (found for free on craigslist!) and untreated wood lying unused around the farm, the team will not just construct (and learn how to construct) these frames but also internalize the principles behind the angled design. The frames will be used as much for hardening off start plants in the spring as for winter gardening, and providing a space to grow our seedlings for summer crops.

Yet another project in the works is the building of a more stable greenhouse on the South Street Farm. Hurricane Sandy blew away our opaque plastic greenhouse, which could’ve been a blessing in disguise. The former greenhouse, although aesthetically pleasing, was made of material too thick for light to really effectively penetrate, hindering its full potential. With all of our reclaimed storm windows, after the cold frames, we’ll set to designing a small, effective greenhouse with glass windows instead of plastic. If you’re ever in the area post-winter solstice, come and check us out! And next summer as you’re harvesting sweet tomatoes and hearty chard, consider winter season extension farming!

For more resources on season extension:

Coleman, Eliot. The Winter Harvest Handbook. River Junction, VT: Chelsea Green Publishing, 2009.

Coleman, Eliot. Four-Season Harvest. River Junction, VT: Chelsea Green Publishing, 1992.

For hoop house equipment and seeds:

Or, you can use PVC piping for hoops like us, purchased from Home Depot at 1.50/10 ft.


  1. Leslie on November 15, 2012 at 3:44 pm

    Do you have to lift up the plastic AND the row covers in order to water, or do you simply life up the plastic sheet and water through the polypropelene fabric? How much and how often do you water?

  2. Groundwork Somerville on November 16, 2012 at 7:13 pm

    Hi Leslie,
    Yes, you should lift both plastic and row cover to water or add fertilizer. You can position the clips that secure both row cover/plastic to the piping more towards the apex of the hoop so it’s easier to roll up the material and access the bed on the side. Depending on the weather really. If it’s dry, a couple days a week. You can also check the moisture of the soil and if it’s damp, you can hold off. You don’t want the crops to completely dry out though so make sure you monitor the moisture every couple of days regardless of weather.