A greenhouse is something that many gardeners desire, and allows them to grow plants all year long regardless of the weather. However, greenhouses can be expensive, which may lead you to look for less costly alternatives to typical materials and construction. Greenhouses need the same basic features, which allows you to be creative in constructing your greenhouse by looking for less expensive alternatives to traditional materials. You can also reduce costs by using recycled materials for your greenhouse structure.
Greenhouses all function in the same general way. Solar energy enters the greenhouse and warms the ground. The air near the ground becomes warm and rises, and the cold air sinks. Then the cooler air also warms and rises, and so on in a cycle. The walls of the greenhouse keep the heated air inside, making greenhouses ideal for growing tropical plants in cold climates or growing plants in the wintertime. The walls of a greenhouse also protect the plants from factors such as wind or birds and insects. While there are many features that you can add to your greenhouse, all greenhouses need the same two aspects. They all need a transparent material to trap the air while letting in light. This material is typically glass or plastic. All greenhouses also need a structure to support the transparent material.
One of the cheapest and easiest greenhouse designs is that of a half-cylinder structure, often called a hoop house. The "ribs" of the cylinder are easy to form and, if the curve is steep, will encourage rain and snow to roll off of the roof of the structure. Typically, these structures are covered with translucent polyethylene plastic sheeting, which is lighter and less expensive than glass. The structure itself can be formed out of almost anything, such as wood, pipe or wire mesh. PVC pipe is particularly suitable, as it is lightweight, inexpensive, easy to bend and will resist corrosion due to humidity inside of the greenhouse.
Glass is typically very expensive, but using recycled sources of glass will reduce your costs. For instance, you can build a greenhouse with old windows. With this type of greenhouse, the walls are made from old windows that are attached to one another, either by attaching them to a wooden structure or attaching the frames together. This can lead to an interesting or even appealing visual effect, but this method requires planning and quite a bit of carpentry skill. This is especially true if your windows are not all the same size. In addition, you should not use windows for the roof, so you will need to use another material, such as translucent plastic roof sheeting.
A cold frame is a structure often built with a greenhouse, and is typically used to acclimate seedlings to the cooler air outside of a greenhouse. Making an inexpensive cold frame for your greenhouse is simple. A traditional cold frame only requires a wooden frame with an angled top and an old window to cover the top as a lid. You can add a hinge to the back of the box to attach to the lid, making it easy to open and close. In addition, you can use polycarbonate plastic sheets instead of glass, which will not shatter.