To protect outdoor plants from frost, there are several methods and materials that can be used. Here are some options:

1. Fabric Coverings: A fabric covering is best because it will allow moisture to escape while still protecting your plants from frost. Fabric coverings will prevent the freezing air from coming into direct contact with the moisture on the plant while also capturing the heat that is radiating from the ground. Bed sheets or comforters work best for covering large plants and shrubs. Newspaper can be used on low-growing foliage, but it can often be difficult to get it to stay in place.

2. Horticultural Fleece: Horticultural fleece is useful for larger garden plants and shrubs. It is a permeable material that is lightweight, breathable, and insulating. You can also use blankets or bubble wrap to create a protective cover.

3. Plastic: Plastic can be used to cover a structure like a frame or stakes around the plants, as long as the plastic will not be touching the plant in any way. However, plastic is not recommended as a direct cover for plants because it can trap moisture and cause damage to the plant.

4. Mulch: A thick layer of mulch, such as shredded bark or compost, can help insulate tender plants. Cover the entire plant with mulch the night before a frost to help protect it.

5. Watering: Watering plants in the morning can help support any protective measures you take. Wet soil retains more heat than dry soil, so watering the soil thoroughly (except around succulents) can help hold heat at the soil level.

6. Cloches: Cloches are bell-shaped covers made from glass or plastic that can be placed over the plants. They are useful for protecting seedlings and smaller plants from frost. You can buy cloches or even make your own out of recycled objects.

When covering plants for frost protection, it is important to anchor the edges down to capture heat from the soil and hold it around the plants, and to some extent, keep frost from settling on the foliage. The more layers of cover, the better the insulation provided. So, you can feel free to cover valuable or tender plants under more than one cover, especially during longer or deeper freezes. It is also recommended to cover plants until temperatures are back into the upper 40’s to 50’s, and to cover them as early as possible and before nightfall.