As we near the end of summer, frost will soon be here to greet us when we awaken.
You’ve toiled all spring and summer in the garden and hate to see the growing season end.
Don’t give up on your growing adventures too soon; you can still produce tasty vegetables, beautiful flowering plants and gorgeous foliage. Let’s explore a variety of ways we can extend the life of our gardens.
There are two types of fall frosts, advective and radiation.
Advective frosts occur when a cold front moves into the area. Temperatures may drop significantly below critical levels; therefore it is questionable as to whether your protection methods will stave off a true killing frost.
Radiation frosts occur on calm clear nights that lack cloud cover to hold in heat. Radiation frosts at the beginning and end of the growing season are typically only a few degrees below critical levels, making crop protection worth your while.
The suggestions provided here will be critical for addressing radiation frosts and may help when the first cold fronts move in.
Based on an average of fall frost dates in Pagosa Springs, we expect a 50-percent chance of frost by Sept. 9. By covering your growing beds with the methods provided, you have the potential of extending your growing season into early October, which is well past the fall equinox of Sept. 22.
Soil, warmed by the sun in the daytime, is the source of heat for frost protection at night. Moist, smooth soil absorbs more heat. To trap heat from the soil around young vegetables at night, place a covering that is low to the ground and spreading. To recharge the heat source for the next night, any covering must allow sunlight to shine through to the soil or must be removed in the daytime.
Grandma’s old method of covering the garden with blankets and sheets works well as long as the fabric remains dry. If the fabric absorbs water, evaporative cooling can lead to colder temperatures adjacent to the blanket. To recharge the heat stored in the soil, be sure to remove the blankets and sheets during the daytime. Covering the flowering plants on your deck and earth boxes full of tomatoes on a chilly, clear night will extend their life and your enjoyment for yet another day.
Floating row covers are lightweight fabrics that lay directly over crops. Because they transmit light, they provide crop protection over an extended period of time without having to be removed. They provide 2-4 degrees of front protection, protect tender plants from cold winds and screen out some insects. If you have plants that need to be pollinated by insects, you will have to remember to remove the covers during the day so that pollination can occur.
Floating row covers are popular in commercial vegetable production where crops planted in large blocks are easily covered. Cool season vegetables that are hardy, such as broccoli, cabbage, kohlrabi, kale, carrots, onions, potatoes, lettuce and spinach usually fair well under a floating row. Many brands and fabric styles are commercially available.
If you decide to use plastic to cover your growing bed, remember that it must be held up off the plants. Therefore, you will need to use plastic in conjunction with some sort of frame, otherwise plants will freeze anywhere they come in contact with the plastic. An easy “cold frame” structure for a growing bed is made with 4 millimeter clear plastic (polyethylene film) draped over a concrete reinforcing mesh. The structure can be easily opened during warm days and closed for cold nights. This structure also works well with a 4-foot wide, raised bed garden system. A plastic covered frame typically provides 3 to 6 degrees of frost protection.
Concrete-reinforcing mesh is available at most hardware and lumber stores. This stiff wire mesh typically comes 5 feet wide in 50 or 100 foot rolls. In trials, the low and spreading shape was ideal for trapping heat from the soil during a frosty night.
Cover the frame with clear, 4-mil polyethylene plastic. Be sure to staple the plastic to the sides of the wood box. In soil bed applications, bury the plastic a few inches along the sides. Hold the plastic onto the frame with small, yet sturdy clips, available at most hardware stores. Clothes pins will not be able to withstand the wind. Hold the plastic closed at the ends with some rocks or bricks.
On cool days, open the top a crack to prevent excessive heat build-up. On a warm day, the plastic should be completely opened to allow plants full exposure to the outdoors. On freezing nights, be sure to close the cover completely. On stormy days with full cloud cover and no direct sun, the cover may remain closed. Not only will the covers provide frost protection, they also increase growing temperatures and provide protection from cold winds.
On extra-cold nights, placing an aluminum space blanket over the plastic on the frame significantly adds to the frost protection. With the aluminized side placed down (towards the plants) a space blanket reflects 99 percent of the heat. They are readily available where camping gear is sold.
In trials done in Fort Collins, topping a plastic-covered, concrete mesh cold frame with a space blanket prevented freezing when outside temperatures dipped to zero following a sunny spring day. The space blanket must be removed each day to recharge the soil’s stored heat.
For a fun and festive alternative, consider adding Christmas tree lights inside the cold frame. In another set of Fort Collins trials, one 25-light string of C-7 (midsize) Christmas lights per frame unit (4 feet wide by 5 feet long) gave 6 to over 18 degrees frost protection. Lights were hung on the frame under the plastic and turned on at dusk and off at dawn. Christmas lights work better than a single, large light bulb in the center by eliminating cold corners and edges.
What happens if you try using Christmas lights and a space blanket? Well they ran that trial in Fort Collins too for those super gardeners. One 25-light string of C-7 (mid-size) Christmas lights per frame unit (4 feet wide by 5 feet long) with a space blanket on top gave 18 to over 30 degrees of frost protection in Fort Collins trials.
Information provided by David E. Whiting, Extension consumer horticulturist, Department of Horticulture and Landscape Architecture, Colorado State University. Colorado State University, U.S. Department of Agriculture, and Colorado Counties cooperating. CSU Extension programs are available to all without discrimination.
Colorado Energy Master Program
Various Colorado State University Extension offices across the state — including Archuleta County — are now offering a new Colorado Energy Master program to educate Coloradans and support volunteers interested in energy issues. Participants can take one or more three-week courses: 1) Energy Today, 2) Energy Efficiency; and 3) Renewable Energy.
Courses are taught by University, utility and Extension staff and include hands-on learning experiences and short field trips. They are targeted for home and small business owners interested in saving energy and money, educators, realtors, recent college graduates and retirees. Each course has been approved for nine hours of Continuing Education Units (CEUs) by the U.S. Green Building Certification Institute and four to nine hours of CEUs through the Colorado Association of Realtors.
The cost of each course is $65, or $195 for all three courses. Aspiring Colorado Energy Master Volunteers take all three courses at a reduced cost of $35 per course or $105 for all three courses. Certified Colorado Energy Masters can volunteer in a number of ways — from conducting basic home energy assessments to educating neighbors and friends.
Registration for fall courses ends Sept. 4. For more information and to register, please visit www.ext.colostate.edu/energymaster. Interested participants may also contact Extension Director Liz Haynes at 264-5931 or Liz.Haynes@Colostate.edu<mailto:Liz.Haynes@Colostate.edu>.
If you have a disability for which you seek an accommodation, contact the Extension Office no less than five days before classes begin.
Sept. 3 — Office closed for Labor Day.
Sept. 4 — Return from State Fair with exhibits.
Sept. 5 — 4-Hers Collect State Fair exhibits.
Sept. 6 — Colorado Energy Master Program, 6 p.m.
Learn more about our upcoming events on our webpage at www.archuleta.colostate.edu.