To protect outdoor plants from frost, the best cover to use is fabric rather than plastic. Fabric coverings, such as bed sheets, comforters, or horticultural fleece, are recommended because they allow moisture to escape while still protecting the plants from frost. They prevent freezing air from coming into direct contact with the moisture on the plant and capture the heat radiating from the ground. Additionally, fabric coverings are more breathable and provide insulation without the risk of damaging the plants. Its also important to erect tall stakes or forms around frost-sensitive plants to drape the covers over them and secure them without worrying about the coverings blowing away or damaging the branches.

When covering plants from frost, its essential to consider the type of plants and the severity of the frost. Different plants may require different methods of protection, and the choice of cover should be based on the specific needs of the plants. For example, young seedlings, tender perennials, half-hardy varieties, and tropical or subtropical plants such as palms and banana plants may require extra protection from frost.

In summary, using fabric coverings such as bed sheets, comforters, or horticultural fleece is the best way to protect outdoor plants from frost, as they allow moisture to escape while still providing insulation and protection from freezing air. Erecting tall stakes or forms around frost-sensitive plants to drape the covers over them and secure them is also important for effective protection.