Greenhouse shelves are a crucial component of a fully functional greenhouse. A typical house will require several different types of greenhouse shelves because different shelving is needed for plant growing spaces than is required for work surfaces and general storage. When shopping for greenhouse shelving, a consumer should consider the materials from which shelves are constructed, whether the shelf system is mobile or permanently mounted, and what function the shelf is intended to serve.
Shelving in greenhouses is generally constructed out of either metal of plastic. Plastic shelving has several advantages. It is impervious to water, which is a major advantage in a greenhouse environment. Plastic shelving is also generally quite light, which makes it easy to install and move. Although modern plastic greenhouse shelving is quite durable, it is not as strong as metal shelving, which is more suitable when load-bearing capacity is needed.
Solid-metal shelving is made out of metal plates supported by a frame structure. Metal greenhouse shelves are also frequently made out of wire or expanded metal. Wire shelves are constructed by welding durable metal wire into a solid cage and are sometimes coated to resist corrosion. Expanded metal shelves are made of sheet metal that has been expanded, or stretched in such a way that it has diamond-shaped holes throughout the sheet. It is then held in place with a metal frame. Aluminum expanded metal shelves offer an excellent balance between moisture-resistance, weight, and strength.
When choosing greenhouse shelves, consider the function of the shelving. Shelves for plants should allow water to drain and, so, should generally not be made of solid material. Side shelves, especially shelves that might double as potting work space, should be solid. This offers protection for materials stored below the greenhouse shelves and allows them to hold loose soil.
If greenhouse shelves are to be permanently mounted in a greenhouse, they should be compatible with the framing material of the house. As a general rule, if a greenhouse is made of plastic, plastic shelves will be the easiest to mount. The producers of some small greenhouses sell special shelves specifically designed to work with their houses. If working with a metal house frame, metal shelving may be a better option, often easier to install as it is generally easier to securely fasten metal to metal than metal to plastic.