Protect Against Freezing Temperatures In The Veg Garden
What is Frost:
Frost occurs when the air temperature approaches freezing, 32°F/0°C. Frost is not always present with freezing temperatures. There are different kinds of frost that cause varying degrees of damage to plants.
Hoarfrost forms on cold, clear nights and is the most recognizable form of frost. This frost is the most recognizable with its fragile ice crystals seen on plant leaves, stems and items exposed to the cold air temperatures.
Rime is a type of frost that happens when water is deposited via dew, fog or watering hose which then freezes. Rime has a glazed appearance.
Black frost doesn’t actually form frost but regardless plants are damaged by freezing temperatures. You will see black leaves and stems.
How do different freezing temperatures affect plants:
Light Frost/Light Freeze: 32° or below for a couple of hours, ice forms on outside of plant but does not affect the cellular structure. This frost will harm tender plants, warm season plants, such as tomatoes, eggplant, squash, peppers, but it can enhance the flavor of many cool season crops such as beets, radish, broccoli, greens, etc…
Hard Frost/Moderate Freeze: 25°-28° for several hours. Plants affected with these temperatures will have damage to blossoms and foliage. The cellular structure of the plant will be damaged but cold, hardy plants will continue to grow.
Severe Freeze/Killing Frost or Freeze: Below 25° for several hours – usually caused by an arctic front. The first and last frost date for a region usually refers to a killing frost. The cellular structure of tender plants is damaged and will not recuperate.
Steps to Protect Plants During Freeze
Water plants thoroughly to prevent desiccation (drying). Water acts as an insulator to soil and plant cells. Make sure to water only the roots, not the leaves.
Mulch with wheat straw, pine straw or leaf litter. A 3” layer of mulch can provide insulation to protect tender annuals or perennials. If seedlings are just sprouting, cover the entire plant with a blanket of mulch to give it extra protection until the temperatures rise above freezing in the morning.
Cover with a frost blanket before the freezing temperatures to trap the heat around the plants. Remove when temperatures are above freezing. Support fabric from touching plants by using hoops.
Cover small plants with pots or buckets after insulating.