By Blake Jackson
University of Missouri Extension’s Frost/Freeze Probabilities Guide signals that gardeners should start considering ways to protect plants from frost, according to MU Extension state horticulture specialist David Trinklein.
Although near-freezing temperatures are not immediately expected, daily temperature averages are declining and daylight hours are shortening, says MU Extension state climatologist Zachary Leasor.
Frost and freeze timing varies across Missouri. Historical data show northern counties typically experience their first frost around October 11, central Missouri around October 20, and southern counties around November 1. In the Ozarks, frost often occurs earlier due to the region’s higher elevation.
“Certain species, especially tropical ones, suffer ‘chill injury’ at temperatures well above freezing. Most species in this category should not be exposed to temperatures lower than 45 degrees Fahrenheit,” Trinklein said. Many of these tropical plants are container-grown and should be brought indoors early in the fall if possible.
Trinklein notes that plant tissue moisture isn’t pure water and does not freeze at 32 degrees. Except for sensitive tropical species, most plants can tolerate temperatures as low as 28°F with minimal damage. Cool-season flowers and vegetables can withstand even lower temperatures depending on the species and acclimation.
Trinklein’s approach for fall plant protection differs from spring. “Be they ornamentals or food crops, they have served their purpose and provided enjoyment and food for the past growing season,” Trinklein said.
“However, in the spring, gardeners are protecting an investment they have made in plants that have yet to pay dividends. Therefore, more aggressive (expensive) measures are warranted.”
Fall protection focuses on preserving latent heat stored in the soil or container medium, often using insulating materials. “This process likely will result in only a couple of degrees difference from under the insulative material versus above it,” Trinklein said.
Products like floating row covers can help. Because soil contains more latent heat in fall than in spring, insulation is generally more effective, though it should be removed during the day to allow sunlight exposure.
Finally, Trinklein reminds gardeners to embrace the seasonal cycle: “To everything there is a season, and a time to every purpose … A time to plant, and time to pluck up that which is planted.” It’s time to prepare for winter and plan for the next growing season.
Photo Credit: pexels-greta-hoffman
Categories: Missouri, Crops, General