Garden Greenhouse

GREENHOUSE STYLES

Free-standing greenhouses are the most common category and include traditional peaked and curved-eave (or curved roof) free-standing greenhouses which are both still very popular in many gardens. Their square or rectangular shape provides maximum growing space, allowing room for benches on both sides and across the back.

Home-attached, or lean-to greenhouses, are designed to attach directly to your home, your garage or any existing external wall provided there is enough height to accommodate the peak of a lean-to greenhouse. Many people find lean-to greenhouses easily accessible and extremely convenient especially when installing the necessary power and water connections for the greenhouse operation.

GREENHOUSE CONSTRUCTION

The most popular opinion held about greenhouse construction is that aluminum frame greenhouses are best suited for a long term installation and are designed to accommodate a variety of glazing materials including glass and polycarbonate.

Aluminum frames are maintenance-free and will generally last a lifetime, making them ideally suited for greenhouse use. Wood frames are not maintenance-free and do not have as long a life span as aluminum frames.

Not all greenhouse frames are built the same so you'll want to be sure you select one that has been engineered to provide adequate structural strength. A quality greenhouse designed with the highest structural frame strength will include the following features.

* Withstand harsh weather conditions such as high winds and an accumulated snow or ice build up in the northern regions.

* Provide the required support for hanging baskets, grow lights, cooling and ventilation equipment and sidewall shelving.

* Include screened hinged storm doors which are a better design than sliding doors. Sliding doors are not as energy efficient as storm doors, and will result in greater heat loss. A screened door also allows extra ventilation when needed.

* An extensive selection of sizes and styles available. Costs or actual available space may dictate the size of a greenhouse.

* Flexibility regarding the potential to use a raised base support for the greenhouse resulting in the need for a "dropped" door.

Consider the desired overall height of your greenhouse. You can build the greenhouse up higher using a "kneewall" to achieve that additional height. However, if you choose to build on a "kneewall", you will need to "drop" the door down to avoid high steps in and out of the greenhouse.

NEW AND USED GREENHOUSES

Glass

Truly a favorite, glass offers a high quality greenhouse covering. It is extremely attractive; allowing plants to be visible from outside, and glass also offers plenty of natural light, especially during winter months. Single and double tempered, unbreakable glass is available. Double glass greenhouses are designed for maximize heat efficiency.

Greenhouse Tip: If you purchase a single glass greenhouse, you can insulate the inside with a layer of plastic. This will help retain heat for the colder months the greenhouse is in use.

Polycarbonate

We offer polycarbonate greenhouse coverings in 6mm Twin Wall or 16mm 5 Wall. These panels have insulating features that can reduce your heating costs by 30% or more. The thicker the polycarbonate, the better it is at retaining heat. Light transmission is diffused through the polycarbonate and the light transmission can be about 10% less compared to glass.

As far as retaining heat, 16mm polycarbonate is best, followed by double glass, then 6mm polycarbonate, then single glass.

16mm 5 wall polycarbonate is the most energy efficient glazing material in today's greenhouse market. The light transmission is slightly lower at 62%. The benefit is an improved R value of 3.03 which is a 21% improvement over our previous 16mm thick triple wall polycarbonate. This means that a greenhouse glazed with our 5 wall polycarbonate will cost 21% less to heat than the previous triple wall polycarbonate glazing. In addition, the 5 wall polycarbonate is about 50% more efficient than insulated double glass, 10mm triple wall polycarbonate and 8mm 4 wall polycarbonate. It is approximately 80% more efficient than 6mm or 8mm twin wall polycarbonate. Arguably, this is the most energy efficient glazing material available in today's greenhouse market.

What's the R Value?

The R value is the unit used to measure the effectiveness of the thermal insulation offered by the greenhouse covering. Different thickness of glass and polycarbonate coverings will result in different R values. The higher the R value, the greater the heating and cooling efficiency.

Listed below are the R values for the various glass and polycarbonate coverings offered:

3mm Single Tempered Glass R Value is 0.95
Double Tempered Glass R Value is 2.00
4mm Twin Wall Polycarbonate R Value is 1.43
6mm Twin Wall Polycarbonate R Value is 1.54
10mm Twin Wall Polycarbonate R Value is 1.89
16mm Triple Wall Polycarbonate R Value is 2.50
5 Wall Polycarbonate R Value is 3.03

BUY A GREENHOUSE KIT

Greenhouses should be easily accessible and careful planning will help map out the provision of your utilities including electricity, water, heating, ventilation and cooling. A southern exposure is preferred, and greenhouse experts recommend that the top ridge of the greenhouse run from east to west. During the winter months, this angle will provide the maximum sunlight exposure for your greenhouse.

For dormant or resting plants a minimum of six hours of light is required. Grow lights can be installed to supplement natural light in order to meet the requirements for your greenhouse.

SITE PREPARATION AND FOUNDATION

Many greenhouse bases are optional. You can purchase a greenhouse base if available, or you can build your own using rot resistant or pressure treated wood.

PRESSURE TREATED WOOD NOW REQUIRES A 10MM POLYETHYLENE BARRIER BETWEEN WOOD AND ALUMINUM SILL TO PREVENT CORROSION OF ALUMINUM. (This requirement has resulted from a chemical change in the way pressure treated wood is processed.)

* A hobby greenhouse under (100 sq. ft.) can be fastened to a 4" x 4" or 4" x 6" treated wood timber foundation.

* For a larger greenhouse a 6" x 6" beam is recommended. Wooden timbers can be stacked to increase the height of the greenhouse.

* For a more permanent site, concrete slabs or concrete footings may be installed. Bricks or masonry blocks may also be used, but ensure the top bricks are closed off, so it a flat surface to fasten the greenhouse to.

* All foundations must be level and square for easy installation of the greenhouse structure.

* Check your local building codes regarding site requirements and to determine whether a building permit is required.

BUY A POLYCARBONATE GREENHOUSE

Greenhouse gardening allows you to maintain an even or optimum growing environment for your plants. One way to accomplish that is by offering greenhouse ventilation and cooling assistance during the warm, summer months.

ROOF AND SIDE GREENHOUSE VENTING

* Roof venting is still considered the best of greenhouse ventilation systems. A roof vent serves as an escape route, but it also provides a source of cool air intake.

* Individually controlled roof vents in the greenhouse 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.

GREENHOUSE 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.

GREENHOUSE 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.

GREENHOUSE 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.

SHADE CLOTH

*The best way to provide cool shade and protect plants from sunburn is with a fabric shade cloth designed for use outside of the greenhouse.

*The exterior shade cloth should sit a few inches above the greenhouse glazing. Do not lay the shade cloth directly on top of the greenhouse glazing. An exterior shade cloth is 40% more effective than an interior shade cloth.

HALLS GREENHOUSES

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).This will provide a natural habitant for tropicals and exotic plants.

To calculate your heat requirements: calculate the wall and roof space of your greenhouse by:

(multiply the width of the greenhouse times the length of the greenhouse) x (the difference between coldest outdoor winter temperature and the desired night temperature) x 1.1

This will provide you with the number of BTU's required to heat your greenhouse. For example, your greenhouse is 8 x 12. The coldest outdoor temperature is 0 degrees F. You want to keep the greenhouse at 65 degrees F at night.

(8 x 12) x (65 - 0) x 1.1 = 6,864 BTU's

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, airspace is created between the plastic and the greenhouse covering.

*16mm 5 wall polycarbonate is the most energy efficient glazing material available in today's greenhouse market. With an R value of 3.03, it is 50% more efficient than insulated double glass, 10mm triple wall polycarbonate and 8mm 4 wall polycarbonate. It is approximately 80% more efficient than 6mm or 8mm twin wall polycarbonate.

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.

BUY A SOLAR GREENHOUSE