What is the best material to cover plants for frost protection?
Written by
Benjamin Miller
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Choosing the proper covering material can make the difference between your plants surviving frost nights or not. Breathable fabrics such as frost cloths or burlap are your best choice. These truly keep the temperature in while allowing air flow. This prevents the deadly moisture build-up that can occur. Plastic alone probably does more harm than good.
Breathable fabrics function in a way similar to natural insulation principles. For example, frost cloth elevates temperatures under cover by typically 4-8°F. I've tested this myself in my garden. When frost fabric is secure, it can create a microclimate that prevents frost from forming around the leaves.
The physics of effective covers relies on the principles of heat retention and moisture. Fabrics that breathe allow water vapor to escape and prevent the entry of infrared radiation. Plastic seals in moisture, which then freezes when it comes into contact with the plant's surfaces. This ice directly damages cell structures.
Fabric Selection
- Choose medium-weight cloth rated for 4-8°F protection
- Ensure material spans entire plant without gaps
- Avoid colored fabrics that limit sunlight penetration
Installation Protocol
- Drape fabric over plants before dusk
- Secure edges with rocks or soil
- Create tent structure for air circulation
Plastic Modification
- Use only as outer layer over fabric
- Maintain 1-2 inch air gap above plants
- Remove completely during sunny days
Proper removal is just as important as proper installation. Remove covers in the morning by 9 am, when the temperatures start to warm up. Leaving the protection on too long puts undue heat stress on the plant. Fold the materials up neatly for reuse. Proper removal is just as important as proper installation. Take the covers off in the morning by
Combine coverings with other measures to protect against extreme cold. Place water jugs surrounded by plants for thermal mass. Use incandescent lights under coverings during hard freezes. These strategies offer additional degrees of protection when the temperature suddenly falls below expected levels.
Read the full article: How to Protect Plants from Frost Effectively
