The thermometer is still stuck at below my comfort level, my plants are shivering in the cold, and I am still focused on gardening on the inside.
Last week's column on building a low-cost cold frame pointed out that you could make a cold frame into a hotbed by providing heat inside the structure.
While adding heat increases the cost, it also extends the growing season.
Whenever anyone asks me what they should build, I ask them what they want it to do. If you want to try and grow plants during the winter, adding a heat source is essential. Our cold winter nights show no mercy to plants when temperatures drop below critical levels.
If you plan to start seeds indoors and use the cold frames in April and May to harden off those plants, a cold frame may work fine. Tomatoes or marigolds are ready to set out in six weeks, so a cold frame is warm enough grow those transplants.
Heating hotbeds and cold frames is not the only temperature-control issue. Preventing plants from overheating is critical, as far more plants die from overheating than from getting too cold.
Structures for plants are small and need minimal heat to keep them from freezing. Look for areas along the south side of a heated building to harvest some of that waste heat.
An overlooked growing space is a large window well on newer homes. These are conveniently tended from inside a basement room. They already have the sides built, so you just need to add a cover over the top to make your hotbed using the heat from the home.
Originally, rotting manure heated hotbeds. To build a hotbed, you dug a deep hole and then built the hotbed over it. The hole was filled with horse manure, and as the manure rotted, it gave off heat.
I built my first hotbed using scrap lumber and a discarded window pane. It worked well but had obvious drawbacks. I had ample horse manure just over the back fence, but most people do not.
Other drawbacks were the smell and decomposition rate. Once the manure decomposed, it no longer gave off heat. You had to remove the plants, dig out the old manure and refill it with fresh manure. That was not exactly a pleasant task on a cold winter day.
More convenient fuels include electricity, natural gas or propane. Since most hotbeds are very small, natural gas and propane are not the best choices because of the cost of the heaters and getting the fuel to the site. Large heaters quickly cook the plants inside the hotbeds.
That leaves electricity as the easiest source. Remember that electricity and wet conditions can be fatal. All wiring needs to be done through a ground fault interrupt breaker. Make certain your setup is done to code and is safe.
The easiest and most uniform heating comes from heating cables encased in vinyl or metal. These are buried in the soil, and the plants are grown in containers or directly in the heated soil. Heat mats on top of the soil also work well. Either of these devices provide bottom heat, which is critical when germinating seeds or rooting cuttings.
The danger of overheating the soil is minimal because the cable has thermostats to provide a specific temperature. Avoid pipe heat tapes or roof heating cables. These are not designed to be buried, and the temperatures settings are usually not suited for good plant growing.
Light bulbs are also good to keep the plants above freezing, but they do not warm the soil. Controlling the light with a thermostat is expensive because the thermostat has to be suitable for a wet location.
If you are going to use the light bulb on a few cold nights, use a weatherproof on and off switch. Put the bulb in a protective enclosure or it will break if a drop of water condenses onto the hot bulb. Small electrical heaters could work, but they overheat and are not safe for wet locations.
Pay attention to the temperatures inside your hotbed. Right now, you could grow lettuce, spinach and other salad crops, some herbs and other cool season crops with very little additional heat.
Later on, you can start vegetable and flower transplants. Just remember to keep the temperature consistent with the needs of the plants you are growing.
Don't overlook rooting cuttings from many woody plants. Starting willows, privet, grapes and other plants is easily done if you provide the right temperatures. You can also get an early start on some perennials if you want to propagate new ones for yourself or to share.
Having that little bit of green, a few blooms or a tasty winter salad makes the work worthwhile. Hopefully during this new year you can be a happier and more productive gardener, regardless of the season.
Larry A. Sagers is a horticulture specialist for the Utah State University Extension Service at Thanksgiving Point.