Guide to Growing Cannabis in a Greenhouse

By on
In Blogs

As more states legalize cannabis for medical and recreational use, many greenhouse growers are taking advantage of the opportunity. While indoor grow rooms and outdoor farms are still popular cannabis cultivation methods, a well-made greenhouse is still popular and has its own merits.

Greenhouse conditions can be precisely adjusted to meet the growing preferences of certain strains, resulting in a more robust crop. A greenhouse protects cannabis plants from harsh weather and pests and can even provide extra security.

Get started with your custom cannabis greenhouse

How Does a Greenhouse Work?

A greenhouse is a building specially designed to grow plants in a controlled indoor environment. Transparent covering material allows sunlight to fill the building, which is absorbed by plants and converted into heat. The resulting warmth stays trapped in the greenhouse to bolster ideal growing conditions.

There are many different types of greenhouses appropriate for growing cannabis, including:

  • Hybrid greenhouse
  • Sealed greenhouse
  • Indoor grow
  • Indoor grow warehouse

Why Grow Cannabis In a Greenhouse?

Growing cannabis in a greenhouse gives your plants the best chance to produce the most potent flower at the highest yield. It can be easier and less expensive than other growing methods and ultimately offers greater control over how your plants grow. While successful greenhouse cultivation still takes time and effort, the benefits outweigh the challenges.

Extends Your Growing Cycle

First, growing cannabis in a greenhouse allows you to grow plants longer into the season. Supplemental lighting and heat can help to make up for loss of daylight in colder months. Not only can you extend your growing season but you can even grow through the winter with the right greenhouse setup.

Ensures An Ideal Microclimate For Growing Cannabis

A good greenhouse provides the perfect climate for growing marijuana plants. Heating and cooling needs can be adjusted as needed without the extreme dryness of an indoor grow room. A greenhouse ensures a stable range of minimum and maximum temperatures to promote cannabis plant growth. 

Cultivate Year-Round

The climate control precision of a marijuana greenhouse allows cannabis plants to bud at any time of year. You don’t have to depend on the seasons to plan your harvest. Instead, you can cultivate your cannabis on a schedule that works for you.

Consistent Harvests

Cannabis crops planted outdoors or in unsealed grow rooms are subject to poor growing conditions. The stable climate of a greenhouse promotes consistent quality and quantity of cannabis crops.


Natural sunlight is a far more energy-efficient light source than electric lights used in grow rooms. While some greenhouses do use supplemental lighting, the vast majority of lighting needs can be achieved free of cost with solar rays.

Provides Protection From Harsh Elements

Outdoor growing operations can be devastated by unpredictable drought, poor soil quality, wind, frost, and torrential rain. A greenhouse prevents outside forces from influencing the growth of your precious plants.

Keeps Plants Safe From Detection

A greenhouse allows you to grow cannabis plants discreetly. And depending on the design of your greenhouse, you can securely lock your plants away to protect them from burglary. In addition, state laws may require the facility to be built a certain way, so that the plants are not visible from the outside.


While growing cannabis is an investment, greenhouse growing doesn’t necessarily require a lot of expensive equipment.

How To Grow Cannabis In a Greenhouse

Cannabis has very particular growing needs. There are many different factors that need to be kept in mind when cultivating marijuana plants, and the methods used in outdoor farms and indoor grow rooms might not be suitable for greenhouse growing. 

Pick a Suitable Strain

There are more cannabis strains on the market than ever before, and each has its own particular growing preferences. The best strain for your greenhouse depends on factors like available space, local climate, and light quality. 

Some of the most popular strains to grow in a greenhouse are:

  • White Widow
  • Trainwreck
  • Blue Dream
  • Northern Lights
  • Chocolate Haze
  • Diesel

Autoflowering Seeds

For greenhouses that rely on natural sunlight, autoflowering seeds are ideal. Autoflowers don’t need a consistent light schedule to bud and won’t be as affected by fluctuations in light. A key advantage of autoflowering seeds is that you can plant them at virtually any time of the year. Not to mention, autoflowering varieties typically take up less space, allowing you to optimize your growing area. 

Feminized Seeds

Photoperiod feminized cannabis can also be grown in a greenhouse under the right conditions. Feminized seeds depend on consistent light to stimulate flowering, and the sun isn’t always the most reliable light source. Growing marijuana from feminized seeds in a greenhouse will require supplemental lighting and extra pruning to keep plants in check. 

Plan Your Grow Window

While you can feasibly grow the right cannabis strain at any time of year, it’s still a good idea to plan your grow window around the seasons if you’re relying solely on natural light. Mid to late spring is probably the best time to start your growth. 

Germinate Indoors

You can also use grow lights to germinate your plants indoors to give them a head start. Once they’ve germinated, you can transfer the seedlings to your greenhouse or outdoor grow space.

Transfer Seedlings To the Greenhouse Gradually

Plant stress can spoil crops, and temperature shock is one of the leading causes. If you’re starting your seedlings indoors before putting them in your greenhouse, be sure to get them acclimated to the greenhouse space first. Introduce them to the greenhouse for a few hours at a time for a few weeks before fully transferring the young plants. 

Supplement Lighting According To Weather

Greenhouses don’t have to depend on sunlight alone to provide sufficient lighting. With the use of energy efficient fixed spectrum LED grow lights, high-pressure sodium lights, or metal halide grow lights, you can easily give your cannabis plants the additional light they need.

Use Blinds or Covers To Force Flowering

Another advantage of using a greenhouse to grow cannabis is that you can force flowering using light deprivation techniques. Greenhouse growers with a bigger budget can invest in automated shutters but blackout covers are perfectly appropriate, too. A good blackout cover can also help to reduce light pollution that interferes with the growth of photo-feminized cannabis plants.

Learn more about us

Pro Tips to Grow Cannabis In a Greenhouse

Like any crop, growing cannabis can be challenging. The wrong amount of light, temperature, or water can keep greenhouse plants from growing strong and healthy. Thankfully, there are some time-tested tips and tricks to produce the best cannabis crops.

Keep an Eye on the Temperature

As important as it is to keep your greenhouse warm, cooling and ventilation are also necessary to maintain optimal growing conditions. Be sure to install a thermometer to keep an eye on the greenhouse temperature and provide additional climate control as needed.

Setup Ventilation

Airflow and humidity are essential for growing the best cannabis in a greenhouse. While some humidity is desirable, too much can promote the growth of mold and mildew. Active ventilation is a proven method to reduce temperature and humidity and allow for air exchanges via natural vents (roof, sidewall, etc.); passive ventilation allows this by using fans, shutters and evaporative cooling. With active ventilation, you’re operating manually or with a motor periodically; passive ventilation requires electricity and costs more to run at all times to keep things cool. 

Plan the Space

The size of your greenhouse will determine how many plants you can grow. So, before committing to a full cannabis growing operation in your greenhouse, be sure that your space can accommodate your plants. Some cannabis varieties aren’t necessarily suited to a confined indoor greenhouse environment. Check the average height of the strain you intend to grow and try to plan for multiple small plants instead of a few giant ones. 

Choose the Right Irrigation

Depending on the amount of time and money you’re willing to spend on your cannabis greenhouse, you can choose a variety of watering methods. You can stick to traditional manual watering, or install an automated drip irrigation system if your budget allows. 

Protect Your Plants

Cannabis is a valuable crop that needs to be strictly monitored and protected. While security measures are important for any greenhouse, cannabis greenhouses require extra precautions to protect budding plants.

Every cannabis grower should install sturdy locks on the doors of their growing facilities. Other security measures like cameras and alarms are also necessary to protect cannabis crops from theft. Depending on the size of the greenhouse, a burglary could result in thousands of dollars of lost product, so security is essential.

Keep It Clean

The more dirt and debris that you have in your greenhouse, the more likely you’ll attract pests and mold. Be sure to give your greenhouse a thorough cleaning before the planting season begins and use sterile soil and containers to plant your crops.

Grow with Prospiant

At Prospiant, we specialize in designing and building controlled environment cannabis greenhouses and indoor grow systems. 

Our team of cultivation experts will work with you to create a custom cannabis greenhouse solution for your unique needs. We’re committed to working alongside you at every stage of your project, from concept to completion and beyond.


Autoflower seeds can reach maturity in around 100 days in a greenhouse while feminized seeds may take several months to grow before harvest.

Ready to Grow Your Business?

Talk to Our In-House Experts

Let's Get Started