Growing Cannabis Outdoors: How To Build A Greenhouse

When growing outdoors you can build a greenhouse to make your grow more discreet and keep nosey neighbors away.
Author Enzo Schillaci
21 July 2020
8 min read
Growing Cannabis Outdoors: How To Build A Greenhouse

Contents:

A greenhouse is usually used to protect plants from cold temperatures, rain and snow, although it can help cannabis growers to have a discreet growing space. The structure of a greenhouse is also super helpful when using the light deprivation techniques, by using a black plastic sheet you can control the light cycle just like you would in an indoor grow tent.

1. Greenhouse

There are several types of greenhouses and all of them are very similar, even though you can buy a green house, building one can be easy. By growing in a greenhouse outdoors you can hide your plants, protect them from cold and even use the structure for plant training and support.

Growing in a greenhouse is a very effective way to protect your plants from cold climates, snow and rain, and keep your plants discreet. Greenhouses are widely used all over the world to grow vegetables, but cannabis growers have adapted them to be used with cannabis plants, this way, you can grow cannabis discreetly, protecting them from harsh environments and allowing you to control the light cycle for vegetative of flowering plants even outdoors by using the light deprivation technique.

There are several types of greenhouses, although all of them are very similar.

The materials needed to build your greenhouse will depend on the climate in your area, greenhouses basically consist of a structure which holds a mesh or plastic sheet. The materials you’re going to use solely depend on the sturdiness and size you want your greenhouse to have.

2. Choose a design

There are basically four greenhouse designs: Lean-to, Tunnel, Gable and Hoophouse.

 

How To Build A Greenhouse: Gable and lean-to greenhouses

It's better to have a bit of experience in construction when building a gable or lean-to greenhouses because they need a sturdier structure.

Even though you can build the bigger ones yourself, it’s better to leave them to people who have experience because they will need a sturdier structure, are usually made out of glass and because of their size, you’ll probably need specific machines to build them without risking yourself or your plants.

 

A hoophouse and tunnel are easier to build and can be built by anyone out of any type of material.
 

These structures are built to grow cannabis or other plants commercially, but don’t worry, there are greenhouses suited for home growers, they are easier to build and depending on the size, you can make them out of wood or plastic (although a metal structure would be better and more resistant).

3. Requirements

Airflow

Before starting, there are a couple of things you need to have in mind.

First of all, you will need to control the temperature and humidity levels, to be able to do this you need proper airflow, if you’re building a tunnel, you can install fans to help you maintain a good ventilation or if you’re planning to build a small hoop-house, small windows on the bottom and on top will allow a good air exchange and help expel the hot air.

 

How To Build A Greenhouse: airflow in a greenhouse

Have in mind that depending on the climate, you may also need a humidifier or dehumidifier to keep the appropriate humidity levels.

Sunlight

Because you’re growing outdoors, you also have to choose a good location, where your plants will get as much sunlight as you can.

You have to build your greenhouse facing the direction where the sun rises, for example, in California the sun rises in the northeast and sets in the northwest, by building your greenhouse accordingly, you ensure the sun will go over your plants and they will receive sunlight all day long.

Also make sure there are no buildings or trees blocking the sun, even though you can grow your plants with less sunlight, consistent sunlight will make a huge difference in their development.

4. Materials

The materials depend on the sturdiness you want to achieve, but here are the most usual materials to build a small and reliable greenhouse for home growers.

  • 40mm PVC pipes
  • PVC connectors
  • Polyethylene plastic sheeting (for cold climates) or Shade netting (for hotter climates)
  • Wooden beams
  • Wood boards (if you want to build a raised bed if you need to) 

 

How To Build A Greenhouse: simple and easy greenhouse

You can build your own greenhouse with cheap and simple materials.
 

These materials are the basic and you can and should adjust according to what you have available and what you think would be better for you, remember this is a general guideline and in no way is the only way to build a greenhouse.

5. Setting up a greenhouse step-by-step

Step 1: Make the base of the greenhouse

The first step is to decide if you’re going to grow in raised beds or if you’ll need to anchor the base of the greenhouse in the dirt.

If you want to grow in raised beds, you’ll have to make them out of wooden boards, have in mind they’ll also be the base where you’ll attach the pvc pipes so they need to be quite sturdy, you’ll then attach the PVC pipes to them with metal clamps, just like this:

 

How To Build A Greenhouse: hold and support the structure

You can use metal clamps to hold the tubes and give them support.
 

If you’re building the greenhouse in your backyard or somewhere you won’t need a raised bed, you can use wooden or metal beams to anchor the PVC pipes to the ground or even make a solid foundation to hold the main frame of the greenhouse.

If you want a discreet greenhouse it's better to build a small one because even though it will be covered, people might get suspicious.

Step 2: Cut the PVC pipes and provide support

You can use one long PVC pipe to make the structure or cut it in half and use PVC connectors to connect them at the top, it really doesn’t matter as long as you make it sturdy.

Make sure you also have a PVC pipe on top to provide more stability, after you connected everything together, it is time to make the structure that will hold the PVC pipes steady.

This structure it’s what will hold your greenhouse together in a storm or if you experience strong wind so it’s better to make it out of wood, in this step it will also be when you decide if you should add a door or not.

The length of the PVC pipes depends on the size of your greenhouse, it really doesn’t matter as long as the final result is something like this:

 

How To Build A Greenhouse: basic structure of a greenhouse

It doesn't matter the size of your greenhouse as long as it has the basic structure.
 

It’s recommended to have a door if you want to keep things more discreet, but if you want to keep it simple, you can always use the plastic sheet as an improvised door and by glueing weights (like rocks or magnets) to the tips you make sure they stay in their place.

Step 3: Building the side “walls”

Depending on the climate, you will use different materials for the walls of your greenhouse, there are two types of materials you can use.

If you suffer from cold climates, it is recommended to use polyethylene, this will allow you to control temperatures and humidity better, also protecting your plants from extreme cold, preventing bugs and pests.

You can use a shade mesh instead of  polyethylene, although this is only recommended if you are growing in warmer climates because you won’t be able to control the environment inside your greenhouse.

 

How To Build A Greenhouse: building the side walls

Even though you can build the walls out of glass or plastic, a polyethilene plastic is effective and cheaper.
 

You can also adapt the structure so you’re able to change the polyethylene for a shade mesh when you need to, use the polyethylene sheet in the winter and the shade mesh in the summer, this will depend on the climate where you live and will help you prevent mold, for example.

The “walls” should be stuck to the structure with duct tape (or something similar) so they don’t rip open.

Remember that even if you’re growing outdoors, it is essential to keep a good environment for your plants, changing in between a plastic sheet and shade mesh will help you control this.

Step 4: Front and back “walls”

The front and end walls will be of the same material you’ve made the side walls. If you choose to have a door, then you will have to build the back wall with a structure similar to the one you build for the door.

 

How To Build A Greenhouse: front and back walls

You don't necessarily need to have a solid wall, you can use polyethilene or a shade mesh to cover both sides of your greenhouse.
 

Don’t forget that if you’re going to have walls in the front and the end of your greenhouse, you will have to add small windows so the air can flow properly, this won’t be needed if you use a shade mesh or polyethylene sheet as the front and back door because they will not be completely closed so they allow air to go through, although it is recommended to have them because airflow is never too much.

Have in mind that the better you build them, the longer it will last, but the windows can be a hole in the walls or if you can make it better, you can build a frame, so you’re able to open and close them.

6. Objective

The result should be something like this:

 

How To Build A Greenhouse: homemade greenhouse

It doesn't matter if you built a small outdoor greenhouse or a big one, as long as you have the basic structure you can start growing your own cannabis.
 

Obviously, it will depend on what was better for you, but as long as you covered the key elements, such as windows, doors, structure and base, all green-houses should look similar at least.

7. In conclusion

A greenhouse is a great way to grow cannabis discreetly and can help you in harsher climates.

Even though it may seem hard to build one, it is fairly cheap and will give you an advantage when trying to control the growing environment outdoors, we recommend trying it out even if you’re not into cannabis, a greenhouse is a great way to grow vegetables and fruits!

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