How to Cover Outdoor Plants

Frost can kill outdoor plants quickly.

Cold snaps can happen almost anywhere that plants grow. Whether frost is an occasional threat in your area or simply a signal of the coming winter, quick action is needed to protect outdoor plantings. Frost creates ice crystals in the plant cells that will cut cell membranes and kill the plant. If you can't bring the plants in for the night, you still have options for protecting them from temperatures lower than 33 degrees F.

Things You'll Need

• Access to weather reports
• Plastic sheeting
• Landscaping cloth or blankets
• Lawn chairs or small tables
• Stones

Instructions

1. Listen to weather reports for predicted temperatures below freezing. Temperatures will not be dangerous until they reach 32 degrees F, especially if winds are calm and plantings are sheltered by a nearby heat source, such as a house.

2. Group container plants, the most vulnerable to a cold snap because their roots are above ground, close together near the house. Take containers that are on stands or tables and place them on the ground as well, or carry them indoors. Arrange lawn chairs or small tables around the outdoor grouping to create support for a tent structure.

3. Throw a blanket or landscape cloth over the supporting furniture. Cover the blanket with a plastic tarp that will touch the ground on all sides of the group of plants. Weigh down the edges with stones or bricks to keep the plastic from blowing away during the night. To prevent frost burn, make sure the plastic does not touch any of the plants' leaves.

4. Set your alarm for sunrise. Get up the next morning and remove the plastic and blanket as soon as temperatures reach the mid-30s. Sunlight on plastic will create tremendous heat inside the "tent" and fry the plants if not removed promptly.

5. Spread landscaping cloth or blankets over beds of plants in the ground, and weigh down edges with stones or bricks for securing. Remove in the morning when temperatures rise above 32 degrees F.

Tips & Warnings

• Water plants thoroughly the day before a frost is forecast. Dried-out plantings are more susceptible to cold. Wet soil will absorb heat during the day, and release it slowly during the night, increasing chances of survival.

• Understand that blankets and plastic sheeting will only provide a few degrees of frost protection. A deep frost lasting several days is likely to be a "killing frost," with no amount of coverage helping outdoor plants.

References

• Texas A&M University: Protecting Plants from Frosts and Freezes
• Cornell University: Understanding Frost
• University of California Davis: Frost Protection in the Garden

Resources

• USDA: Protection of Plants from Frost
• NASA: Climate Change Shifts Frost Seasons