How to keep your garden growing

Working with numbers has always made my eyes cross, but when I read that a cold frame can capture the heat of the winter sun and change the temperature in a spot in my garden from a Zone 5 to a Zone 6, I decided to reexamine my aversion to numbers.*

Fall is a good time of year for planting cool-weather crops like spinach, kale, onions and beets. If they’re sheltered in a cold frame, they’re likely to continue to grow well into the winter. Fresh greens from your garden for Thanksgiving? It’s a possibility.

I talked to one of my Master Gardener friends, Pat Trimble, who utilized a cold frame for a number of years. She built it using left-over lumber and an old window. Pat said “For me, the risk of losing the crop negates a large investment in a commercial cold frame, and it is fun and a great thrill if you get a bowl of lettuce to eat on a frigid January day.

A cold frame relies on the sun as its only heat source. One of its beauties is in its mobility and Pat relocated hers several times. As is true of all real estate, the success of a cold frame depends on location, location, location. Pat says you have to know how the sun moves around your property to find the best site. She said the hardest part of using a cold frame was deciding where to put it.

To maximize solar absorption, the cold frame should be situated in an area facing south or southeast with good drainage. Placing the cold frame against a northerly wall or hedge will help protect it against the frigid winter winds.

Pat thinks the ventilation learning curve is not as steep as people might think. She said she normally spent at least part of a winter day walking around her garden, so opening and closing the box to adjust the temperature was not an inconvenience.

Although Pat put her cold frame on top of the soil, utilizing the earth’s insulating powers by sinking the box into the ground will also aid in protecting the delicate crops. I asked Pat if she used bags of leaves or straw bales for protection and she didn’t. She said, “I might have thrown a few weeds beside it, but no, my cold frames never had any additional insulation.”

If you garden in Blair County you realized long ago that we’re not in the sunshine capital of America. Winter cloud cover is a persistent condition here. You can engineer a little more light and a few more degrees of heat in a cold frame by painting the inside of the frame white. That will reflect a smidgen more sunlight and an additional degree or so onto your plants.

n The USDA Cold Hardiness temperatures are -20 to -10 degrees Fahrenheit for Zone 5, -10 to 0 for Zone 6.

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