December

In December, I have three cold frames under cultivation.

The fall spinach is the smallest, and I harvest heavily from it in December. I take the largest leaves and give the small leaves more time to grow.

The fall lettuce will not last the month, so I also harvest heavily from it.

The spinach inside the winter garden cold frame is thriving under the glass, but I avoid harvesting from it in December. I take only the largest leaves and the small starter leaves close to the ground. I want as many of these plants to be large and mature in January as possible. I exhaust the fall spinach and lettuce before turning to the winter spinach.

December has short days, and as the daylight decreases, the growth rate of the plants also slows down. The angle of the sun is too low to warm the interior high enough to harm the plants, so the glass covers stay on during December. If, however, the forecast calls for a gentle, cold rain, the covers come off. The rain will benefit the plants. I fertilize both spinach plantings lightly on December 15, but I skip the lettuce.

During December, the temperature works its way lower forcing several changes. I anticipate these changes by carefully noting the forecast. When a prolonged period of below-freezing temperatures is predicted, I harvest all the remaining fall lettuce and break down and store away the fall lettuce cold frame. I also turn the soil in preparation for spring planting. A serious bout of winter will soon transform the landscape.

I also break out the cold weather insulation covers and tarp to hold the covers in place. They are placed over the glass of the winter garden during the cold winter nights, and they come off during sunny days so the sun's light and warmth can penetrate the glass. When the nighttime low approaches 10 degrees, the insulation keeps the internal temperature above freezing, often over 40 degrees Fahrenheit. With the sun's warmth during the daytime, the temperature often climbs to 55 to 60 degrees. This is an ideal temperature range for spinach.