Protecting plants from frost can be quite easy. Twenty minutes of work on an evening when frost is expected will save many plants. The secret is having the materials you will need on hand and ready - burlap, micropore plastic (row cover sheet or weedblock), insulating blanket, shredded or bark mulch, and Cloud Cover antitranspirant.
Make sure plants are well watered. The air temperature above moist soil is about 5 degrees warmer than
over a dry soil. Spray your plants liberally with Cloud Cover. It slows the rate at which plants lose water to the surrounding air, preventing drying and wilting.
Move container plants under an eave or put them in the garage. If you choose not to move them, protect them like in-ground plants as follows: Cover the sensitive plants with a porous, lightweight covering. Freezing air flows over the cover and the unfrozen soil beneath buffers the cold. Beneath the covering, air temperatures may be 8 degrees warmer the first night of frost and 5 degrees warmer on succeeding nights. You can safely leave the covers on for one or two cool days. Remove the covers if the days warm up and re-cover at night should the threat of frost continue. If using non-porous vinyl or plastic sheeting must be supported so it does not touch the foliage (they have a tendency to supercool the plants and will freeze them.)
If you have already applied a mulch around your plants, it’s simple to heap the mulch closer to the main stem of the plant for added insulation. (Be sure to remove the added mulch from around the crown after the frost is over.)
Read our full handout on frost protection and frost recovery here.
