CHOOSING A GREENHOUSE
A greenhouse can be a major investment, and information on greenhouses and equipment for controlling the environment will help a person decide which green house is most suitable.

GREENHOUSE STYLES

The traditional peaked or curved roof free-standing greenhouse is still very popular in many gardens. The square or rectangular shape allows for maximum growing space, with benches on both sides and across the back.

Home attached or lean-to greenhouses were designed when backyard space was limited.  These greenhouses are easily accessible and very convenient for connecting the necessary power and water.

GREENHOUSE STRUCTURES

Aluminum framed greenhouses are designed to carry a variety of greenhouse coverings. Not all greenhouse frames are the same so look for the engineered structural strength and design in a greenhouse.  A quality greenhouse designed with the highest structural strength will have the following features.

• Be able to withstand extreme conditions, such as high winds and accumulated snowfalls.
• Have the required support for hanging baskets, grow lights and sidewall shelving.
• An intricate part of the greenhouse design is to have screened hinged storm doors and large individually roof or side vents.
• An extensive selection of sizes and styles available.  Costs may limit the size of a greenhouse, but extensions can be added at a later date.
• The door can be lowered or dropped into an opening in the foundation to eliminate a high step?

GLAZING MATERIALS

We offer four different glazing options from tempered single and tempered double glass to 6mm twinwall polycarbonate and 16mm triplewall polycarbonate. Our glazing options allow our greenhouse customer the choice of greenhouse coverings to suit their needs.

• Tempered single glass has a proven record as a quality greenhouse covering because it provides the plants with the maximum amount of natural light . The tempered single glass in our "Traditional Greenhouses" minimizes breakage and offers a safety feature of eliminating serious injury in the event of a broken piece of glass.
• Our tempered insulated double glass has all the bebefits of single glass with an insulation factor optimized for full service use in cold climates.
• Our 6mm twinwall polycarbonate glazing provides the benefits of 50% better insulation compared to single glass for reduced heating costs, light diffusion for built in shading and cooling as well as privacy, and a nearly unbreakable strength is ideal for schools or any high traffic situation. Along with the reduced heating costs compared to single glass, the light diffusion and insulation factor will keep the greenhouse from heating up too quickly in the morning and cooling down too quickly when the sun sets. This moderated the temperature for the plants resulting in the best possible growing environment.
• Our 16mm triplewall polycarbonate glazing has all the benefits of the twinwall polycarbonate, while offering an insulation factor that is 35% better than the twinwall polycarbonate and 19% better than double glass.
• Our glazing options can be intermixed in the same greenhouse to add extra insulation and light diffusion where it is needed while maintaining aesthetic appeal and optimal.
  

GREENHOUSE SITE SELECTION

• The greenhouse should be situated so it is easily accessible.
• Experts recommend that the ridge of the greenhouse run east to west. During the winter months, this angle provides maximum light transmission.
• For dormant or resting plants a minimum of six hours of light is required.  Grow lights can be installed to supplement light requirements for the greenhouse.

SITE PREPARATION AND FOUNDATION

• When selecting a site for your foundation, a flat, level surface is essential so that the greenhouse can be easily installed, stable and secure. Locate your greenhouse close to power and water, while also considering water drainage and easy access. Try to locate the greenhouse so that 6 hours of sunlight is available during the winter months.
• Whatever your choice of material for the foundation, the base must be level and square, and built to the exact outside dimensions of the greenhouse. (A foundation sketch will be provided.)
• If you will be having raised foundation, lowering the door to ground level is a free option. This is called a door drop. The opening to leave for the door will be noted on your sketch and this dimension must be confirmed upon order.
• The most economical foundation is a row or two of 4 x 4 timbers (or 6x6’s for larger greenhouses). If possible, concrete blocks or sona tubes in the corners will also help to keep the timbers from eroding. Other foundation options include a concrete slab or a raised concrete wall. The higher a foundation is raised, the more head room becomes available inside the greenhouse for hanging baskets and tall plants. (The standard side wall height of all BC Greenhouses is 5’ 6”.)

VENTILATION AND COOLING

The main aim of greenhouse gardening is to maintain an even or optimum environment for the plants.

ROOF AND SIDE VENTING

• Roof venting is still considered the best of ventilation systems. A roof vent serves as an escape route, but it also provides a source of cool air intake.
• Individually controlled roof vents allow the intake of cool air to be a gentle flow to bench level, not a strong force that suddenly lowers the temperature.
• Glass louvers or hinged side venting is also very common at the bench level or lower. Side venting will certainly assist in cooling the greenhouse in the warmer seasons.

AUTOMATIC VENT OPENERS

• Automatic vent openers are self-contained units which require no electricity.
• On a sunny day, heat will build up around the cylinder mechanism, and the vent will slowly start to open. Similarly, as the air cools around the cylinder the vent will close.

GREENHOUSE EXHAUST FANS

• Will a greenhouse require an exhaust fan?  This depends on the type of venting system that is built into the greenhouse structure, and if there is shading on the exterior of the greenhouse.
• Specialty greenhouses for orchids, chrysanthemums, or tropicals, require  exhaust fans to maintain a controlled environment.
• The ideal requirement for air exchange in the greenhouse is one complete air exchange per minute.

AIR CIRCULATION

• To equalize the temperature and distribute air evenly within the greenhouse, one should ensure constant air circulation.
• Condensation can be greatly reduced if there is constant air circulation. For the best results, it is recommended that one install a small circulating fan to maintain a continuous movement of air.

SHADING

• During the spring and summer, direct sunlight can quickly overheat the greenhouse and destroy both plants and seedlings.
• Exterior shading is the most effective method of preventing heat build-up. Shade cloth, or screening material, has been used by commercial growers for many years and is now available for hobby greenhouses.
• Higher density shade cloth is more suitable for orchids or other tropicals.

HEATING

HEATED GREENHOUSE ENVIRONMENTS

The night temperature in a year-round greenhouse is the most important factor to determine which heating system is required.  The greenhouse gardener also determines whether to winter over plants or to provide a constant growing environment.

Cool or frost free greenhouses maintain a night temperature of 40-45ºF (5-7ºC). This is suitable for frost sensitive plants and rooted cuttings

Warm greenhouse requires a night temperature of 55ºF (13ºC). Growlights are necessary for adequate light conditions in this environment.

Hothouse night temperatures are set at 65ºF (18ºC). The natural habitant for tropicals and exotic plants.

HEATING COSTS

• Warm greenhouses can be twice the cost of a cool greenhouse.
• Insulating the greenhouse can reduce the heating cost by 30% or more. To the inside of the greenhouse frame a clear 4 mill plastic liner is fastened with a clip. Then an airspace is created between the plastic and the greenhouse covering.

GREENHOUSE HEATING UNITS

• Heating requirements depend on the size of the greenhouse, the night temperature required and the expected outside low temperature.
• Electric heaters are the most common source of heat for a small greenhouse.

THERMOMETERS

• The greenhouse gardener becomes very dependent on a maximum-minimum thermometer. This thermometer records the daytime high temperature and the overnight low temperature.
• The thermometer readings will determine whether to adjust the heating thermostat.