A Beginner's Guide to Building A Greenhouse

There are many factors to consider before setting out on your greenhouse adventure. First and foremost, you need to consider your location, budget, square footage, and crop. These factors will help you decide what style of greenhouse you want to build. I put together this guide to help get your farm on the right track. I’ve listed additional articles below that may provide you with further detail. Let's get started!

Style of Greenhouse
            There are many different styles of greenhouses. I will cover the most popular greenhouses used when growing hemp or psychoactive cannabis. Through my experience, I have seen two main styles used. Of course, you can vary from these styles to find what works the best for you.

• Free-Standing Greenhouse – This is by far the easiest and most affordable style. This style is most ideal for growers working with less than 10,000 sqft. Free-standing greenhouses require less site preparation as well. The main detail that sets this style apart from others is the self-supporting design and limited connections.
• Gutter-Connected Greenhouse – This style is most ideal for growers with more than 10,000 sqft of space. This style has the opportunity for unlimited connections at the roof level. This means that your greenhouse could be as long as 300 feet. This style creates lots of vertical height for air, shade cloth, and artificial lighting. If growing in the colder months, heat can be more centralized and energy costs can be up to 25% less compared to a free-standing greenhouse. Utilities are easier to install as well.

Style of Roof
            In this section, I will cover the three different styles of roofs most commonly used in a greenhouse. Each style varies slightly, but all of the styles offer similar benefits. The only difference you will notice during construction is the amount of materials needed and additional installation.

• Quonset (Hoop) – This is the most common style seen on greenhouses. The hoop style roof allows for easy installation and the option for cheaper materials.
• Gable (Roof) – The gable style allows for rigid walls with an angled roof. Similar to a house. This can require more materials and a larger budget. This is an ideal option for those using wide pane glass for the glazing.
• Gothic – The gothic style roof is the strongest design for a greenhouse. This most ideal for those growing in regions with high winds and lots of snow. A gothic roof follows the design of an arch. This can help provide an ideal microclimate.

Glazing
            Greenhouse glazing is essentially what you are covering your structure with. Of course, you want to find a material that is transparent and long-lasting. In this step, I do not recommend cutting corners. Depending on the duration of your operation, you want to find a material that won’t fade and retains its R-value over time. Here are a few materials that I recommend.

• Double Polycarbonate – Low-cost, but only four year life. Provides insulation.
• Corrugated Polycarbonate – Expensive, average life of twenty years. Provides insulation.
• Acrylic Structured Sheet Glazing – High insulation value, very expensive.
• Wide Pane Glass – Ideal for high light levels during the winter. Need to use shade screen to reduce heat loss and provide shading.

Heating
            When building a greenhouse, you have to consider the environmental factors in your area. This can be easier said than done, but don’t overlook this step. When it comes to heating your greenhouse, there are a few techniques that will help you lengthen your growing season.

• Hot Water Boiler – Creates steam to heat your greenhouse. Ideal for high square footage.
• EPDM Tubing – This is an effective way to heat the roots of plants if using raised beds. The tubing contains hot water that is constantly circulating. Can be placed in sand layer or under concrete. Used to heat roots and rooms.
• FIN Radiation or Heat Exchangers – Can be pricey, but very effective. Can be placed around perimeter or on the roof structure.

Cooling
            Cooling off your greenhouse in the middle of the summer can present some challenges. Make sure you locate your greenhouse in an area where it can catch the summer breeze. Here are a few ways to keep your greenhouse cool.

• Fan and Louver – Allows for ideal temperature control. Ventilation rate of 2 cfm/sqft in winter and 8 cfm/sqft in the summer.
• Evaporative Cooling – Place fans and fog machines strategically around greenhouse. The extra moisture created picks up the extra heat.
• Horizontal Air Flow System (HAF) – Small fans placed around greenhouse to create horizontal air movement.

Irrigation
            Choosing the right irrigation system for your operation can help keep labor costs low. Anyone can walk from plant to plant with a hose or container, but this can become very timely and inefficient.

• Computerized Boom Irrigation System – Very versatile. Allows the grower to water at different rates.
• Ebb and Flow Watering – This is a very contained watering technique. Requires a main reservoir to hold water.

Supplemental Lighting
            With my experience in Colorado, we commonly use supplemental lighting to lengthen our growing season. Make sure you use the right lighting and intensity for your square footage.

• High Pressure Sodium (HPS) – Very inefficient. Ideal for flowering plants.
• LED – Energy efficient. Can be used throughout the duration of the plant’s life cycle.

*Watts to Sqft. : 400-600 watts per sqmeter or per 10 sqft. Need at least 500,000 watts for 10,000 sqft.

Miscellaneous
            In this section, I will cover a few techniques that will help increase your chances of success. These techniques will help save you time and money.
            Energy conservation is at the forefront of our society. And why not? Practicing energy conservation techniques can help you save money and time. When trying to insulate your greenhouse, you may want to consider double glazing and perimeter insulation. This can help lower your monthly heating bill. Energy/shade screens can help keep your greenhouse cool and limit the need for an A/C. Lastly, utilizing your full growing space can create higher yields.
            Most growers these days want to set up their operation with monitored controls. These controls can monitor the temperature, ventilation, irrigation system, and many more. If you have the extra budget, I recommend investing in an electronic controller to control your greenhouse. The electronic controls can open and shut vents, turn on the heater, and even control your supplemental lighting. This is ideal for those growers with limited man power.
            Depending on your location, it is important to build a freeze barrier underneath your greenhouse. Typically, this is done prior to the construction of your greenhouse. Without a freeze barrier, you open yourself up to the risk of frozen roots or quicker greenhouse deterioration.
            Lastly, I would like to briefly cover the budget. The size, technology, and crop are all major factors that will effect your budget. If you are a hobby grower, a large budget will not apply to you. If you are an industrial grower with a big operation, a large budget is something to consider. On an industrial scale, the average budget needed is between $8,000 and $21,000. The lowest amount of money I've seen spent was $5,000 for a decent industrial greenhouse. Remember, don't cut corners!
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​Here are a few articles to help you get one step closer to harvest:
https://ag.umass.edu/greenhouse-floriculture/fact-sheets/selecting-building-commercial-greenhouse
https://www.420beginner.com/best-practices-for-greenhouse-hemp/​
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​Conclusion
All in all, building a greenhouse should be an exciting and rewarding adventure. Make sure to put forth the additional research and don’t cut corners! This can really make a difference between the success and failure of your crop. Please don’t hesitate to email us if you have any questions. Please subscribe to our newsletter for additional tips and guides that will be posted throughout the season.

Happy Hemping!

Sean Huber
​Marketing Director, AP Sleeping Indian LLC

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