Reference
An Overview of Season Extension Methods
The short answer
Gardeners extend the season with a ladder of simple covers. Floating row covers are lightweight fabric laid over plants or on hoops; cloches cover individual plants; cold frames are clear-topped boxes; and hoop houses (low tunnels or high tunnels) stretch plastic or fabric over hoops. Each traps solar heat or blocks wind to buy extra growing weeks in spring and fall.
In general, each added layer raises a plant's cold tolerance modestly, and combined methods can extend the season by several weeks. Choose based on how much protection, cost, and permanence you want, from cheap movable row covers to sturdier tunnels.
The main methods
- Floating row cover: lightweight fabric laid directly on plants or over hoops; cheap and easy to move
- Cloche: a clear cover over a single plant, such as a jar or a plastic dome
- Cold frame: a clear-topped, insulated box that traps solar heat
- Hoop house / low or high tunnel: plastic or fabric over hoops, creating an insulating air space above the plants
How much protection
Adding layers increases cold protection incrementally, and structures that hold an air space above the foliage protect better than fabric resting on the leaves. Combining methods can push the harvest several weeks longer at each end of the season.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- University of Minnesota Extension — Extending the growing season: start early, end later — Overview of row covers, cold frames, and tunnels for season extension.
- NC State Extension — Appendix E. Season Extenders and Greenhouses — Describes row covers, cloches, cold frames, and tunnels as season extenders.
- Oregon State University Extension — Lengthen growing season by building a coldframe or cloche — Cold frames and cloches trap heat to extend the growing season.