Plan now to extend the growing season

By Jean English | Sep 18, 2011
Photo by: Jean English Extend the growing season for Swiss chard and many other crops by building a cold frame or making low hoops to cover the crops in the fall.

With a little planning and perhaps some construction now, you can have greens from your own garden all winter and spring. A cold frame; some low hoops covered with row cover and, later, with plastic; a low-tech hoop house, or even windowsills full of potted greens can keep the crops coming.

A cold frame is a bottomless box that sits on garden soil. It can be as long as you want; four-feet by eight-feet is a good size to start with. The back of the box should be about 12 inches high and the front about eight inches. Site the box so that it’s conveniently close to the house; so that it isn’t sitting in a wet spot; and so that the slope faces south and the box gets as much fall and winter sun as possible. A clear cover can be made from recycled windows, from plastic stretched over a wooden frame, or from Plexiglas. Good construction directions appear here, thanks to Eliot Coleman: http://images.taunton.com/enewsletters/vg/kg04-cold-frame-plan.pdf.

Another option is to bend hoops from 10-foot-long, half-inch metal conduit, and stick them in the ground about 10 inches deep or in a wooden frame. Set the hoops about five feet from one another. Johnny’s Selected Seeds sells hoop benders (johnnyseeds.com/c-597-quick-hoops-low-tunnels.aspx) that make low tunnels that are four feet or six feet in diameter to cover one or two garden beds, respectively.

The $59 item is a great tool for community groups or libraries to buy and share. The hoops are covered with a fabric row cover early in the fall, and that row cover is covered with a second layer of greenhouse plastic around mid-November. The row cover and plastic are held down with bags of sand or with rocks placed at each hoop.

For more information, see “Extend the Growing Season with Coleman’s Double-Covered Low Tunnels” at mofga.org/Default.aspx?tabid=844; and “Use Low Tunnels to Grow Veggies in Winter: Quick Hoops” at motherearthnews.com/Organic-Gardening/Low-Tunnels-Quick-Hoops.aspx.

Johnny’s also sells a pipe bender to make a low tunnel; you can walk in this one — a treat in Maine’s long winter. You might even grow hardy crops in cold frames or low hoop structures inside one of these low tunnels for extra protection from the cold.

Be sure to vent your structure when the temperature inside it gets to 60 degrees; otherwise you can cook your crops.

Johnny’s suggests sowing the following crops in August and September so that they’re established before the day length drops to below 10 hours (around Nov. 5 in Maine); after that, they won’t grow much. Those with an asterisk can usually be harvested all winter (if the cold frame or low hoop structure isn’t covered too deep in snow):

• Basil

• Beets

• Broccoli

• Cabbage

• Carrots*

• Cauliflower

• Cilantro*

• Collards*

• Endive

• Escarole

• Kale*

• Kohlrabi

• Lettuce*

• Radicchio

• Radishes

• Salad mixes

• Spinach*

• Swiss chard

• Turnips

Here are other suggestions compiled from other sources. You can see that opportunities exist for playing around with crops and planting dates.

Sow in mid-July:

• Dandelion

• Endive

• Escarole

• Parsley

• Radicchio

• Scallions*

Sow August 1:

• Carrots*

• Kale*

• Swiss chard (for March, April, May harvest)

Sow in mid-August to early September:

• Arugula

• Cilantro*

• Claytonia*

• Collards*

• Kale*

• Lettuce

• Mache (corn salad)*

• Mustard greens*

• ‘Olympic’ onions (from Johnny’s; for June harvest)

• Spinach*

• Lettuce

• Minutina*

• Mizuna

• Radish

• Sorrel

• Spinach*

• Tatsoi*

• Turnip greens*

Sow any time in fall or winter (for early spring harvests):

• Arugula

• Claytonia

• Lettuce

• Mache

• Radish

• Spinach

Sow in mid-November:

• Carrots (to germinate in March)

You can also dig plants, such as Swiss chard and kale, from one spot in the garden and transplant them to your coldframe or hoop structure; or place the season-extending structure over existing vegetables.

In the spring, use these structures to grow early potatoes, kale and other crops.

A small space that is covered during the coldest months can save hundreds of dollars on grocery bills. And many of the crops that are exposed to cold temperatures, such as spinach and carrots, taste best after they’ve been naturally chilled.

Jean English lives in Lincolnville.

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