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Cool Season Gardening

Cool Season Gardening

Estimated read time: 4-5 minutes

This archived news story is available only for your personal, non-commercial use. Information in the story may be outdated or superseded by additional information. Reading or replaying the story in its archived form does not constitute a republication of the story.

Larry A. Sagers Regional Horticultural Specialist Utah State University Extension Service Thanksgiving Point Office © All Rights Reserved

Some gardeners can hardly wait to get out and start planting. With changeable weather in the spring, many have a hard time deciding when to get started. Understanding plant growth and its relationship to microclimates enables you to start the gardening season several weeks earlier than would otherwise be possible.

Microclimates are climatic factors immediately around the plant. In our area, frost protection is the primary consideration, but increasing temperature is just as important. Wind protection also helps young plants grow much better. When considering devices and techniques to extend the gardening season, choose easy to use, durable materials that do not overheat young seedlings.

Natural heat from the soil is a very important climate modifying factor. Moist soil absorbs three times more heat during the day than dry soil providing four to six degrees frost protection for young plants.

Bare soil absorbs four times as much heat as soil covered with grass, weeds or an organic mulch and further increases frost protection. Well prepared seed beds also store more heat than rough soil. Just a few degrees difference in the microclimate can make the difference between the survival and death of the plant.

Soil stores heat very well. To protect plants, trap as much heat from the soil around the tender young plants as possible. The simplest plant protection devices are waxed paper hotcaps used by tomato growers for many years to get a week or two head start on the season.

Paper hats or plastic milk jugs or buckets serve the same purpose. One problem with hotcaps is they often become overheated during the day. Coverings left on in sunny weather need openings to vent out excess heat. If you use milk jugs, save the caps. On cold days, place the caps on the jugs in the late afternoon and then remove them the next morning to allow the heat to escape.

One ingenious device, the Wall of Water, provides frost protection by storing extra heat from the sun warming the water. Wall of Waters have an open top to allow the heat to escape so they do not overheat. Although they absorb heat from the sun and release it at night, the major reason for their success is that water releases significant amounts of heat when it freezes.

Since each Wall of Water holds 3 gallons of water, they can protect plants down to temperatures in the mild teens. More importantly, they provide additional heat so warm season plants grow better. Set out Wall of Waters at least a week prior to planting to allow the soil and the water to warm up to avoid shock to the plant. Other water type devices include milk jugs or pop bottles arranged in circular patterns around the plant.

Plastic mulches also work very well. Black plastic mulches raise soil temperatures about 3 degrees. Clear plastic mulches will raise soil temperatures up to 10 degrees. This enables gardeners to get a two to three week start on the growing season. Some of my most successful production has come with using clear plastic mulches and Wall of Waters to get plants off to an early season start.

Row covers are another important way to promote early plant growth. Clear plastic cloches can be made of glass, clear plastic or spun polyester. In many European countries, small glass, A frame structures enable them to ripen vegetables that could not otherwise be grown.

Clear plastic over a frame of wire hoops or concrete reinforcing mesh also works. Use clothes pins to hold the plastic in place and be sure to have a suitable way to vent the cloches on sunny days.

Spun polyester row covers are also popular for home gardeners. Remay is one of the many different brand names. It is available for home gardeners and is sold as Garden Blanket. The advantage of these row covers is that they are lightweight and allow both air and water to penetrate.

They will not overheat nor do they require significant modification of irrigation systems to use them. In addition to the above mentioned devices, proper use of transplants also help extend the garden season. Tomatoes and peppers are commonly transplanted, but many cool season crops such as lettuce, cabbage, broccoli and cauliflower also transplant well.

Difficult to transplant crops such as melons, squash and cucumbers can also be transplanted if done carefully and the plants are not too large.

Getting a jump on the garden season is not a difficult nor expensive process. It requires a basic understanding of how plants grow and how to trap and utilize the extra heat coming from the sun.

Careful attention to these details often makes the difference between an early producing, successful crop and crops that do almost nothing. In addition, early season production gives you special bragging rights on how early and how productive your own garden has become.

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