Getting the Basics Right for a ‘Greener’ Greenhouse
November 22, 2016
The greenhouse is a valuable tool for any professional grower. As with indoor grows, using a greenhouse puts you in control of the environment. But greenhouse gardens receive intense, full-spectrum sunlight, which indoor grows don’t get. This gives your plants some benefits that are available only outdoors.
From small grows to large-scale commercial operations, the foundation is the same for success. So, let’s break greenhouse construction down to the basics: choosing building materials to suit your needs, determining the covering to control the elements, and adding system automation.
Choosing your materials
Before starting, find a spot that receives the most sunlight each day, then mark off the size that you want your greenhouse to be. A best practice is to make it larger than you think you’ll need. You’ll appreciate later on having an extra amount of room.
The next step is to choose your materials for both the frame and the floors. (By the way, don’t be afraid to mix and match materials to build your ideal greenhouse.) Here are the three leading choices for frames:
- Wood: When planning the greenhouse structure, consider easy-to-maintain, durable material for the frame. Wood is great for a building that will be pleasing to the eye, and it’ll be easier to hang materials and weighted objects. But wood structures can be more prone to damage from humidity and strong weather.
- Metal: On the other hand, metal structures last longer. They won’t expand and contract as much as wood—which is a must-have if you’re in an area with weather extremes. Your choices for metal are usually aluminum and galvanized steel. Prefabricated metal greenhouse kits are available online, and your team can assemble these structures with relative ease.
- Plastic: Some cultivators will use plastic, such as PVC, in their structure. PVC frames tend not to be as sturdy and modifiable as metal frames, but they’re a good choice for your first structure. However, they’re not recommended in areas with high winds.
Greenhouse floors can be poured concrete or pea gravel. The highest priority in choosing your floor is ample drainage, since standing water is bad for any garden. So, plan your greenhouse to ensure that water drains out and away from the building, which will help keep mold and other waterborne issues to a minimum.
Covering your plants
Next, choose your greenhouse covering. Make this choice with consideration to your local weather, amount of sunlight and wind patterns, as well as how you plan to use the space. If you want to get a head start on spring planting and to grow later in the season, your building covering options may be different than if you plan to use the greenhouse to grow all year long. There are two main types of covering materials, glass and plastic.
Glass: A glass covering is not the best choice; it’s heavy and not the best type of insulator. Using it for your entrance and exit doors is fine, but not for the main area of the greenhouse. But if this is your choice, make sure you use two- or three-panel insulated glass. Just expect to pay a little more to cover an entire building with it.
Plastic: Several options are available for plastic, with thickness determined by the product’s “R rating.” This standard commercial unit measures the effectiveness of thermal insulation. Polyethylene, polycarbonate and fiberglass are all offered in a variety of thicknesses, and fiberglass is provided in both rolls and corrugated sheets.
- Polyethylene film has a longer lifespan and can be UV treated. A more efficient choice than glass, polyethylene can help save you a tremendous amount in heating costs—some studies show up to a 40% savings. This type of plastic can be used in a single or a double thickness, giving you plenty of options for heating and cooling.
- Polycarbonate that is UV-treated can have a clarity similar to glass. It’s durable and resistant to impact and fire. Using up to five layers can create an economical heat retention system that will keep a greenhouse warm all season long. This is a good option for greenhouses that require heating often.
- Fiberglass is a great replacement for glass, but it has a translucent appearance. It’s an excellent multi-season choice, keeping your greenhouse cool in the summer and helping retain heat during the winter. Fiberglass delivers more options for covering your roof and sides with ease.
Automating your greenhouse
Finally, greenhouses can be automated to help you stay on top of the workload. Here, you’re limited only by your imagination. Some of the most popular controls are supplemental lighting, watering, heating/cooling and air flow.
- Supplemental lighting can extend seasons or start plants early, helping your garden produce all year around. You may find that you’ll need to add a light deprivation system to maximize your alternative light needs.
- Water should be accessible from all points of the greenhouse. Use overhead hoses to direct water to specific spots, or run water lines directly to each container. This type of watering system can work for hydroponics as well. Setting the water on a timer assures an even, healthy growth.
- A heating and cooling system guarantees that your greenhouse stays within optimal temperature zones. It often will rely on thermostats and exhaust fans. Some greenhouses have rooftop louvers, which open when the temperature reaches a preset level, to let hot air vent from the roof. You can also set exhaust fans to activate when the greenhouse reaches a certain temperature.
- Intake air should always be filtered and cleaned before it enters the room. Add heaters and air conditioners when needed. Ceiling fans and wall-mounted oscillating fans are important to keep air moving steadily so that each plant takes in enough fresh air.
When creating a greenhouse system, your goal is to bring indoors as many of the benefits of the outdoors. Using the sun’s power provides increasing opportunities all year long. But you can take control of the positive attributes of the outdoors to grow more green in your greenhouse.
By Eric Stone
Cannabis Cultivation Today articles are for informational purposes only and should not be considered legal guidance or advice on grow practices. You should contact an attorney or a qualified cultivation consultant for specific compliance and cultivation advice.
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