Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

simple as a window sash laid over a rectangle of straw bales or a piece of plastic stretched over a metal or PVC pipe frame and held in place with clamps. Duct tape also works wonders to keep plastic in place. The advantage to plastic sheeting is that it can be removed during the day to take advantage of fresh air and the sun’s warmth and then replaced at night to protect plants from cold air. The cold frame can easily be converted to a hot frame by installing electric heat and a watering/misting system.

Black plastic mulch conserves moisture and stops weeds in this hoop house.
    Greenhouses can be attached (lean-to, window-mount, even-span) or free-standing. A lean-to uses an existing structure for one or more sides and is limited to single or double-row plant benches with a total width of seven to twelve feet (2.1-3.6 m) and length up to that of the building. Without considering security, the advantages of the lean-to are its proximity to electricity, water, and heat, but on the downside are its limited size, light, ventilation, and temperature control.

This photo was taken in Nijmegen, Netherlands, in late November, 1985, at the original Cannabis Castle started by Neville, owner of the Seed Bank. Plants grow in small squares of rockwool. The white box at right is a heater.
    A window-mount replaces an existing window providing a relatively low-cost way to grow short plants, small seedlings, or clones. It can be installed fairly simply with common household tools. The disadvantages are its small size and possibly public view.
    Low profile greenhouses are perfect for crops of short plants. It is easy to set up a low profile hoop house or a greenhouse alongside a building that gets full sun. The short greenhouse or cold frame is simple todarken during full summer and lets you reap the benefits of the harvest early!
    Small greenhouses and cold frames also work well on patios, balconies, and rooftops. They protect plants from wind and prying eyes of neighbors.
    An even-span can be an attractive option. Like the window-mount or lean-to, the even-span is attached to the house and bears similar limitations of size, light, ventilation, and temperature. Unlike the lean-to or window-mount, the even-span can be larger and can open into the house–providing heat and humidity–or even function as a conservatory, an attractive place to relax. It is, however, more expensive to heat and maintain. Such greenhouses are most popular where security is a minimum concern.
    The freestanding greenhouse offers the most flexibility in size and location. It can be built to take full advantage of the sun, but it does not retain heat well and can be expensive to keep warm. Many frame types and coverings are available in kits or raw materials. There are also a number of good web sites such as http://www.wvu.edu/~agexten/hortcult/greenhou/building.htm to help you choose the plan that works best for you.
    Framing can be in wood or metal. You may select a panel frame which is more expensive to build (panels are individual units) but has the advantage of quick installation and breakdown for storage. If portability is an issue, there are miniature greenhouses and hoop houses which can be purchased as a kit for under $300. These structures, because they can be picked up and moved, are usually considered temporary by municipalities and often do not require permits. For more information on types and prices, visit web sites such as www.hoophouse.com .

The female seedling transplants in this greenhouse have just been watered. Even though they were transplanted late, they still grew out well.
Coverings
    Options for coverings are more extensive than those for framing. The traditional greenhouse is glass. Glass, besides compromising security, is heavy, expensive, and easily broken. Plastics and fiberglass can provide safe, economical alternatives.

Early-flowering crop in a greenhouse shows these ladies touching leaves. They are 3 feet (90 cm) tall.

This backyard greenhouse near Paris, France was recently planted.
    Plastic is much cheaper than glass (a sixth to a tenth of the cost), can be heated as effectively as glass, and is equal to glass in producing quality plants and buds. Polyethylene (PE) is low cost, lightweight, provides ample light, and can withstand fall, winter, and spring weather. It does not tolerate summer UV levels, however, and must be replaced annually. Ultra-violet inhibited PE lasts longer, but both types lose heat more quickly