A greenhouse combines the large yield of outdoor growing with the control and security provided by indoor growing. In general, the average cost of one ranges from $7,000 to $28,000, according to Home Advisor.
If you go about it the right way, creating a DIY greenhouse could prove substantially cheaper. In this guide, we show you how it is done. First, let’s check out why you would want to grow cannabis in a greenhouse.
The Advantages of Growing Marijuana in a Greenhouse
A greenhouse combines the advantages of indoor and outdoor cultivation. For some growers, it is a more practical option than an indoor set-up. Perhaps they have little interior space but a large garden, for instance. Here are some of the plus points.
Lower Energy Consumption
When you cultivate cannabis indoors, you have to ensure your plants get at least 18 hours of light a day during the vegetative stage. This means investing in grow lights and also facing a hefty energy bill. With a greenhouse, your plants benefit from sunlight just like they do outdoors.
Ideally, you will build a greenhouse on your property. Keep it locked, and you’ll make it hard for thieves to break in and steal your cannabis. You also manage to adhere to the ‘keeping the cannabis out of public view’ part of state law. Moreover, you also significantly reduce the risk of pest infestation.
Protection From the Elements
When you grow marijuana outdoors, your plants are at the mercy of the elements. If you live in a climate with inclement or unpredictable weather conditions, your plants are at risk. A sudden frost could kill your crop overnight. Meanwhile, high winds and heavy rain could also cause havoc. With a greenhouse, you retain control over temperature and humidity.
Higher Quality Cannabis & Greater Yields
Outdoor-grown marijuana tends to provide higher yields than its indoor counterpart. Also, users may benefit from more potent and flavorful buds.
Now that you know the pros let’s continue by outlining how you can build a marijuana greenhouse.
Designing Your Greenhouse
There are numerous design options for greenhouses, though the majority are similar. Regarding materials, a lot depends on your climate and how sturdy you want the greenhouse. Here are the most popular options:
- Polytunnel: As the name suggests, this type of greenhouse has a tunnel shape. Polytunnel greenhouses tend to be large and feature a decent standard of build quality.
- Pop-Up: This is the greenhouse of choice for someone on a budget. They usually consist of a plastic cover, frame, zip-up door, and shelves to hold some tools. You don’t get much in the way of security or size with a pop-up greenhouse, however. Therefore, make sure the location of the greenhouse is secure.
- Walk-In: This form of greenhouse is a slightly higher standard version of a pop-up. It also consists of a simple metal frame and plastic covers. However, a walk-in greenhouse is larger, so you can grow more marijuana.
- Gable: This greenhouse has a flat, sloping roof that is connected to vertical sidewalls. The angle of the roof dictates the height as well as how snow and other materials slide off. You’ll find that gable greenhouses often use rigid plastic panels or even glass for the transparent material.
- Lean-To: This greenhouse design involves using an existing building, usually your home, using it as one of the walls. A majority of people with lean-to greenhouses build it on the south or east side of a house.
- Hoop House: This greenhouse design involves covering a metal or plastic hoop structure with a layer or two of clear plastic.
If you have money to spend, you can buy a high-standard greenhouse online quickly and easily. These greenhouses typically consist of aluminum frames and polycarbonate panels.
When choosing a site for your greenhouse, make sure it matches the dimensions of the grow space available. Remember, you also need some free space to move around inside the building. Finally, set it up in the part of your garden that gets the most sunlight.
Building Your Greenhouse
If you plan to build a greenhouse, the best design options are the tunnel and hoop house versions. While a metal frame is the best option, you can also use plastic or even wood. Before we outline the material required for a DIY greenhouse, let’s analyze some key requirements.
It is essential to consider how you plan to control your greenhouse’s temperature and humidity before you begin. Those building a tunnel greenhouse should install fans to ensure good airflow. If you plan to create a hoop house, adding small windows on the top and bottom should suffice.
It would help if you also considered the fans you want in your greenhouse, which will depend on the size of the building. Also, please be sure that the outtake and intake fans have a Cubic Feet per Minute (CFM) rating that’s at least equal to your greenhouse’s volume.
Calculating CFM is as easy as multiplying the structure’s height by its width by its length.
Calculating CFM is as easy as multiplying the structure’s height by its width by its length. Therefore, a greenhouse that is 10 feet high, 12 feet wide, and 8 feet long has a volume of 960 cubic feet. A grow space’s volume is also the required CFM to ventilate it each minute. As a result, its CFM is 960 in this example.
When setting up the fans, place them above and below the canopy. This process will stop old air from getting trapped inside the greenhouse and increasing the humidity and temperature inside.
Adjusting your watering schedule is important to ensure there are no humidity issues. Outdoor growers should avoid their typical watering habits. Water evaporates from the soil much faster outdoors than in a greenhouse. As a result, watering plants as you would outdoors will lead to overwatering.
One option is to pay a little extra for an automated watering system. Drip irrigation systems are becoming increasingly popular amongst experienced growers.
Your plants will benefit from sunlight in a greenhouse, though it all depends on where you live. California residents will find that their plants receive sunlight all day once they position their greenhouse accordingly, for example. Also, ensure that no trees or buildings block the sun.
If you live in a region that doesn’t have sunny conditions, you may still require grow lights. Generally speaking, LED lighting provides the best results. The set-up costs are higher than other forms of lighting, but they’ll keep your energy bill down in the long term.
Assembling the Greenhouse
There are various methods of building a greenhouse. Today, we focus on a basic set-up that involves the following materials:
- Wood boards (If you want to grow in raised beds)
- Wooden beams
- PVC connectors
- 40mm PVC pipes
- Shade netting. If you live in a cool climate, use polyethylene plastic sheeting instead.
Here’s a quick guide to help you assemble your DIY greenhouse easily.
Building a Base
Growers who want to cultivate in raised beds need to use strong wooden boards. In this scenario, you must use metal clamps to attach the PVC pipes to the boards. If you don’t need a raised bed, use metal or wooden beams to anchor the pipes to the ground.
Developing the Greenhouse’s Shell
It is possible to create the structure using very long PVC pipes. Another option is to cut a pipe in half and use connectors to connect the PVC pipes at the top. It is also good to place a PVC pipe on top to ensure the structure is more stable. The length of the pipes dictates the size of your greenhouse.
Bending the pipes enables you to create a tunnel or hoop house structure easily. The result is several pipes bent in the shape of an arch.
We recommend including a door with your greenhouse for the sake of security and discretion. However, an alternative is to use a plastic sheet to cover the entrance and glue rocks to the sheet to keep it in place.
Adding the Walls
Polyethylene sheets are the best option if you live in a cooler climate. This material protects your plants and helps you control the greenhouse’s temperature and humidity. Shade mesh is a viable alternative if you live in a warmer climate like in Southern California. However, please note that with mesh, you can’t control the greenhouse’s environment. Use duct tape to stick the sheeting to the structure to create your sidewalls.
Adding front and back walls means you should include small windows for the sake of better airflow.
Make sure you use the same material for the front and back walls. If you decide to have a front door, your back walls must have a similar structure. Adding front and back walls means you should include small windows for the sake of better airflow. A quick and easy way to create ‘windows’ is to cut holes in the polyethylene. However, you compromise security by doing this.
That’s it! The above is a great option if you’re on a budget or lack the DIY skills to create something more sophisticated.
Additional Tips on Creating a Greenhouse for Marijuana
Now that you’ve built a greenhouse, here are some tips on getting the most out of it.
- Benefit From a Longer Growing Season: You can alter the length of your crop’s grow cycle. With a greenhouse, you ensure the air around the plants remains warm during sunny weather even while the temperature outside falls. This enables you to lengthen the growing cycle and benefit from larger buds.
- Cleanliness is Crucial: As is the case with indoor grows, it is essential to keep the greenhouse clean. Otherwise, you’re inviting pests and diseases.
- Plant Training: Consider using SOG, SCROG, topping, and other growing techniques to get the most out of the greenhouse’s space.
- Drainage: Apart from having easy access to fresh water, you also need a place for water runoff drainage.
- Buy a Thermometer & Hygrometer: These tools help you retain control of the greenhouse’s environment. Knowing the temperature and humidity ensures you can act fast if either measurement is too low or too high.
Final Thoughts on Building a Greenhouse for Weed
There are several ways you can build a greenhouse for your cannabis. However, you can keep things simple and use a combination of PVC pipes and polyethylene sheeting to create it in a few hours.
The initial investment varies but could prove substantial if you want a high-quality greenhouse. Once you install it and get everything in order, you could benefit from several harvests per year. Remember, a greenhouse enables you to cultivate cannabis in cold weather.
After each harvest, perform some checks on your greenhouse. This includes going through ventilation, lighting, security, and so on. Use the time between grows to perform maintenance and repairs and perhaps buy new equipment. If you’re serious about growing high-quality cannabis with bountiful yields, a greenhouse is a fantastic option.