Greenhouses are available in all sizes, shapes and degrees of strength. They can be bought in unassembled packages, assembled on site and ready to set on foundations, or custom designed for a specific need. Most greenhouse structures fall into three types. The attached lean-to greenhouse has one sidewall as a part of a house, garage or other building. The lean-to is less expensive to operate and construct, but there may be some drawbacks in cooling or ventilating this type of greenhouse.
The window design greenhouse is attached outside a conveniently located window and may be an economical solution for some homeowners. It’s very challenging, however, to maintain a uniform temperature in this type of greenhouse because heat is dependent on the interior home heating.
The free-standing greenhouse is the most versatile, when maintaining a good greenhouse environment. This type of greenhouse is easy to ventilate all year long, and can be easily expanded if necessary.
When considering where to place the greenhouse, consider the exposure the greenhouse would receive from a certain location. An eastern or southern exposure is the best for the lean-to greenhouse. Locate the greenhouse out of shade, especially in the winter months.
Materials for the framing of the greenhouse may be composed of untreated wood, aluminum alloy, steel stone or brick. The material you may decide upon will depend on the budget, durability, types of plants to be grown and aesthetics of the structure. If a wood framework is chosen, use a type without wood preservatives, such as Penta or creosote. The most popular woods, western red cedar or Douglas fir, resist rotting and are a good choice for greenhouses. Aluminum and steel are generally colder than wood but in small greenhouses the amount of heat loss due to this factor is limited. Aluminum generally requires less maintenance than a wood structure.
Hobby Greenhouses: Benches, Shading & Supplies
Greenhouse benches may be made of cypress, concrete, wire or fiberglass. The material you decide to use will depend on your budget, types of plants you grow, aesthetics and durability. Generally, benches are positioned in a permanent location in a hobby greenhouse, but larger, movable benches are also available.
A bench constructed approximately 30 inches high and no more than three feet wide allows easy access from one side. Legs and a box frame made of two-by-fours with wire pulled over the frame and stapled into place is adequate for many hobbyists. This type of bench is best suited for potted plants.
You might want to build a bench that not only holds potting soil, but also allows you to plant directly in the soil. These benches weigh considerably more and require more support.
Benches may also be tiered, but be sure to allow adequate growing space between the tiers. These benches may present a problem when excess moisture from the upper shelf collects on plants on the lower shelf. They may also require additional lighting.
The intensity of sun in the High Plains and Rocky Mountain West means you’ll need to provide plants with shade. Fortunately, there are several inexpensive ways to cover greenhouse glass and protect plants from Colorado’s intense summer sun. One way is to mix whitewash or hydrated lime with water, then apply the mixture with a roller or sprayer over glass surfaces. However, lime solutions are not recommended for aluminum-framed greenhouses. Another inexpensive solution uses one gallon of white latex paint and eight gallons of water. Simply apply the mixture with a roller in late spring and it will wash off by the following fall. Commercial shade cloths made of aluminum, vinyl, plastic and other materials are also available.
Other supplies you will need in the greenhouse include a potting bench, potting-soil storage bins, a seed-storage area, a sink for cleaning, artificial lighting, and hoses and nozzles for watering and cleaning out containers.
You can start with a minimum of equipment and add items each year. A good minimum-maximum thermometer is essential because it will allow you to monitor temperatures in your greenhouse.
Record keeping is also important, because it will allow you to look back and learn from the problems and successes you experienced in previous growing seasons.
ARS Landscape Materials & Supply, Denver, Colorado