Protecting Plants During Cold Weather

Greetings Happy Gardeners and Happy New Year! It's been a busy month since my last post. I hope everyone has been having a successful winter planting season. I am looking forward to the upcoming new year and the spring/summer planting season, it's hard to believe that in only a month tomatoes will be in the ground!

Today I would like to talk about how to protect your garden from extreme cold temperatures.  Over the last few years the Southwest has experienced an extraordinarily high occurrence of record low temperatures in addition to the record setting heat we have been experiencing during the summer months.  It can only be speculated as to what is causing our winters to be colder and summers to be hotter, but as desert gardeners we must be able to adapt to these wide fluctuations of daily temperatures.

Winter gardens are planted with types of plants that are not just tolerant to colder temperatures but actually benefit from a light frost. Occasional dips  to 32 degrees improve the taste of leafy greens and are generally no cause for concern. However, when daily temps hover in the 30's and dip to the low 20's at night, and do so for an extended period of time like they did this past week, we must take additional precautions to protect the garden.

When I first began gardening I would cover my plants whenever I got cold. It was not uncommon for me to cover plants around 40 degrees. I know now that this was going way overboard.  At this point, I only protect my plants when temps approach the "hard freezing" point of  below 28 degrees and generally I do it only if the temps are going to stay below that level for more than a few hours. If temps have been warm but suddenly dip into the low 30's, I may also protect plants in that situation since they may not have adjusted to the sudden drop in temperature.

Although I personally have had a full bloom sunflower in my front yard in February, I would not recommend that you waste time trying to keep plants going that just aren't made for cold weather. If you have a warm space inside, and at least 6 hours of direct sunlight, it is possible to keep your tomatoes and peppers through the winter, but this requires a lot of effort on the part of the gardener. It is generally better to start off anew next spring. I know I am probably stating the obvious to some, but we were all new to gardening once!

Of the winter vegetables most commonly planted in Tucson, beets, Brussels sprouts, carrots, collards, kale, parsley and spinach are the most cold tolerant. Certain varieties of kale are even known to grow through the harsh Siberian winters! Temperatures between 31-26 degrees will not kill broccoli, cabbage, cauliflower, chard, lettuce, mustard, onion, radish, or turnips, but the plants will begin to experience leaf burn.  Peas are the least cold tolerant winter crop, and will begin to die near the freezing point of 32 degrees.

If only a few precautions are taken, it is possible for garden plants to survive temperature dips into the teens and maybe even lower. Brr! The following techniques for protecting your garden can be also used on any landscape plants or citrus trees that may be sensitive to frost damage. Mulching your plants is essential for conserving water in the desert, but mulch also acts as an insulator protecting the roots from the cold. The water conserved also has an added benefit since water also acts as an insulator. In fact, it is a smart idea to water your garden a day or two before a frost is expected. The water will better hold the heat of the day and will create a warm micro-climate when combined with a cover at night. You may also consider misting your plants lightly before sunset. The frozen water will create an igloo effect insulating leaves from the colder outside air.

Covering plants is often the first and only method gardeners use to protect their plants. While a great step, all to often it is done inadequately. Sheets and frost cloth must completely cover the plants to ground level in order to be effective. While draping covers on top of the plants does work, it is more effective to utilize a frame around the plants so the frost protection can be put up and taken down efficiently.

Sheets should be taken down promptly in the morning, especially if they are opaque, but frost cloth can be left up all day for those too lazy to do this burdensome chore. Both sheets and frost cloth can be doubled up for added protection. One last note on covers, never use plastic to cover your plants.  It will trap cold air and actually cause more harm.

A permanent covered garden for starting plants is called a cold frame.  A cold frame is an enclosed box with a hinged lid that allows light in but will trap heat. Cold frames are an excellent way for starting plants from seed outdoors if you lack the light and space for doing so indoors. There are many online plans for building cold frames, and many can be made from recycled materials for very little cost.

Most of us, not my neighbors, but most of us have taken down and put away our X-mas lights. If you're a smart gardener you'll keep a few extra strands handy for cold nights. X-mas lights, especially the older kind with large bulbs put off a large amount of heat.  Running a few strands through your garden bed combined with the other methods discussed will keep your garden toasty warm all night.

For me, I think tonight I'll try a large mug of hot coca and a warm cat. Until next time,


Happy Gardening!