Growing Weed in a Greenhouse

Growing Weed in a Greenhouse
November 16, 2020

There are plenty of advantages to growing weed in a greenhouse. Some of you may think of those large structures that probably cost hundreds of thousands of dollars. For sure, that is not what you need for personal use. Yet, there are small options that you can quickly set up in the garden or backyard. Regardless of size, they are versatile in that you could cultivate whatever types of seeds – regular seeds, feminized seeds, or autoflowering seeds, even clones.

Granted that there is space inside the house to set up a grow tent, or even a spare bedroom to turn into a grow room, you may still find other reasons. For one, marijuana plants – as well as all other plants – thrive naturally outdoors. In this case, a greenhouse protects them from the elements – extreme weather conditions, pests, and grazing animals. Perhaps these are not enough reasons, but they most certainly can benefit growers in colder regions – Northern Europe, for example – significantly.

Although there is an initial cost entailed, they are still cheaper than the operating expenses racked up by artificial lights. Even if you were to use powerful HID lamps – MH + HPS – none can match the sun’s complete spectrum. Consider, too, that the enclosed exposure lets you have the ability to control the climate, and it becomes possible to cultivate marijuana all year round.

What Are the Advantages of Growing Marijuana in a Greenhouse?

You can control the weather and climate inside a greenhouse, regardless of the season. By installing some equipment, you can manipulate life cycles at any time of the year. The sun – being your primary source of light – saves you a bundle than if you were to grow indoors. These are among the most significant benefits you can expect.

Supplemental Lights and Control

As the season changes, daytime duration changes too. You can still control the length of light exposure by installing supplemental lighting to extend the “daylight” hours.

In regions where daylight is short, you can extend the vegetative period to give your plants more time to grow in mass. On overcast days, you can augment sunshine (or lack of) by using artificial lamps. These are additional costs that you have to think about and highly recommended, but not mandatory pieces of equipment. Should you opt for them, the electric bill would be much lower than relying on them exclusively in an indoor garden setting.

Apart from necessities, the flexibility afforded by the ability to control lighting lets you manipulate life cycles. One common practice in greenhouse cultivation is light deprivation during summer seasons. As much as you want to maximize light exposure, you can completely cut off the light, forcing marijuana plants to begin the flowering stage. One reason why you want to do that is to harvest buds to avoid heavy rains or excessive cold in the fall season.

On the other hand, you can continue to grow the plants through the fall and winter. In this case, then you definitely need to invest in additional equipment that helps control the greenhouse atmospheric conditions.

Climate Control

One indoor grow room’s concern is air circulation, which directly and indirectly affects the three most critical atmospheric conditions affecting marijuana. These are temperature, humidity, and access to fresh air. These are also your primary considerations with a greenhouse. Hence, before choosing one type over the other, think about how you want to control the climate.

If a greenhouse has fixed panels, then you may have to use fans and vents – exclusively. On the other hand, by opting for one that has windows or panels that can be opened or removed, you have more flexibility here. It is easy to allow wind circulation to keep the plants cool or get rid of excess heat buildup by opening them up – without additional costs.

It does not mean that you no longer require other equipment. You cannot control outside atmospheric conditions, and they do affect indoor conditions. For example, a dehumidifier may be needed during heavy rains or cold to keep the humidity level under control.

On incredibly hot days, opening some panels to let heat escape may not be enough. You would need fans or an air conditioner to prevent heat stress. And if it is too cold, then you would need a heater to keep the plants from freezing to death.

Yes, those are equipment that cost money. But think of it like this. Most of the time, you take advantage of what nature provides. It is only when conditions are not optimal that you use the necessary equipment to keep providing the best environment for your plants.

By the way, the choice is yours. You can keep it cheap and straightforward, with no frills, or go high-end with automated climate control.

What Kind of Greenhouse Is Ideal for Marijuana Plants?

Once upon a time, the only way for you to have a greenhouse in your backyard is to build one. Even when small greenhouses started appearing in the market, their costs were prohibitive. A few things happened, though, in the last couple of decades. Increased demands and mass production led to stiff competition. You are the winner here because they are better and cheaper than ever. The three choices that suit home use are freestanding, polytunnel, and lean-to.

There are numerous choices, for sure. So, before pointing your finger at one – maybe it is affordable, or available, and whatever other reasons – these are the things to consider.

Size of Greenhouse

Are you planning to put the plants in the greenhouse when they enter the vegetative stage or start them inside from seeds or clones? Do you have a sizable space in the garden? It is going to be a problem for the neighbor if it affects their view?

The good news is that there are different sizes to choose from, and you could even have a small 4′ x 4′ walk-in greenhouse.

Greenhouse Frame

The structure of the greenhouse deserves plenty of thought, too. They could be steel, aluminum, wood, or plastic. Each, of course, brings unique advantages to the table, while also having weaknesses.


Galvanized steel is the preferred choice for commercial marijuana farming. Reasonably cheap and long-lasting are among the advantages of growing marijuana in a greenhouse with a steel frame. Moreover, because they are naturally sturdy, there is less framework. Fewer materials (and thinner, too) means less shadowing and maximum light coverage. Be sure to choose galvanized or stainless steel tubes because they can resist corrosion and last a long time.


Yes, aluminum is expensive, but it is the most beautiful and sustainable type of greenhouse framing material. Compared to other materials, aluminum pays for itself over the long-term because it does not rust or break down from UV exposure.

This material is quite sturdy and can carry plenty of weight (such as glass panels). One caveat is that due to thicker materials (channel bars), the frames cast some shadow inside the greenhouse.


Advancements in plastics have made it a popular material for greenhouse framing in the last decade. They are cheap and easy to install. Usually, you find this material in small structures, where strength is not as much needed. Often, too, they come with metal wire supports.

Plastic is a poor conductor. Hence, this material loses less heat compared to metal and wood.

A disadvantage of plastic material is that UV causes it to decay. Choose one that has a UV protective coating, and they should take you some 20 years.


The most commonly used material for home greenhouses is wood. Aesthetically, that depends on its finishing. They could look rugged or premium. Mostly, wood frames are covered with rigid plastic sheets. But it could also be designed to have glass panels.

Wood, however, is vulnerable to insects and decay. For this type of frame to last long, be sure to pick cedar or redwood. And be careful when applying chemical sealants as you do not want its residue spreading to the plants.

Compared to steel, wood loses less heat. But because they tend to be heavier and larger in size, they cast shadows on the plants.

Panel or Cover Type

Once you have decided on the size, it is time to determine which type of cover is suitable. Clear panels are ideal for starting seedlings because it allows direct lighting. But if you plan to grow the plants until reaching full maturity, you are better off with opaque panels. That is because diffused light is better suited for the flowering stage when the plants develop buds and cannabinoids/terpenes. An excellent choice for this purpose is to get a greenhouse kit with twin-wall polycarbonate walls, although there are other choices.


Of all the materials used for covers, none is as durable as glass, which can last a quarter of a century – unless it broke accidentally. Forget that it has practically no insulation value because it loses both heat and cold quickly.

For this material to be viable for insulation, its strength needs to be doubled or tripled. The good news is that there’d be a decreased risk of breakage during installation. But glass is already a heavy material. Hence, you could imagine how much more cost is added as a glass greenhouse would need more substantial framing to support the load.

When you think about the cost and benefit, perhaps the other materials merit more consideration.


You have several choices here – fiberglass, acrylic, polycarbonate, and polyethylene film. All of them are shatterproof and can reasonably withstand hailstone. Moreover, they are flexible and can be fitted on curved surfaces. If needed, they are available in large sheets, which means there is no need for unnecessary framings. Fewer joints also reduce the possibility of leaks.

Fiberglass. It is the first viable replacement for glass. Fiberglass, unlike glass, can diffuse light and thus make for a virtually shadowless greenhouse. It can retain heat, but not as efficient as polycarbonate or polyethylene film. During summers and winters, they transmit less heat, which is a useful trait. Usually, they should have a service life of around six years before turning yellowish.

Acrylic. This material is often compared to polycarbonate. Both have around 80% to 90% light transmission, which is ideal for growing marijuana in a greenhouse. Although suitable for its intended purpose, it is not as durable and requires a certain amount of heat to be cut, bent, or shaped.

Polycarbonate. UV-treated polycarbonates are becoming a popular choice for greenhouse construction. For one, they are more durable than any other plastics. Moreover, they are resistant to impacts. A single wall is the cheapest, but not useful. At the very least, go for double-layered (or tripled) for enhanced strength, heat-retention, and light-diffusing properties. Usually, these panels would last around 15 years.

Polyethylene Film. You are not likely to use PE for your home greenhouse set up. Usually, it is used in commercial farming, lasting 3 to 5 years before being ditched and replaced. Its suitability also depends on the number of layers and UV treatment.

Local Climate

Consider the local climate as it affects growing weed in a greenhouse. For example, if you live in a place where heavy snowfalls are the norm during winter, choose a greenhouse kit with excellent insulation to keep the plants warm and cozy. You do not need thicker walls if winter is not that harsh, or there is no winter season. And if the outdoor condition is naturally hot, then be sure to choose one that has adequate ventilation for heat to escape.


Whereas the greenhouse kit size is determined by needs and garden space, the location is dependent on the sun. You should set it up for southern (or southeastern) exposure. This location gets no shade throughout the day, not unless there are adjacent buildings or tall trees. Avoid northern exposure as this location receives some shade throughout the day.

Orienting the greenhouse depends on your needs. Generally, an east-west orientation receives less light than north-south.

If the primary purpose is to propagate plants or germinate seeds and transplanting them during summer, you need less sunlight. Orient the greenhouse for eastern or western exposure. This way, there is some shade during the day. You also do not have to deal with excessive heat buildup.

As already stated, the southern exposure is most ideal for growing marijuana plants all the way to maturity. In this case, you can place some shade to control the amount of sunlight reaching young plants, and remove them as they enter the vegetative stage.

Be mindful of positioning a greenhouse near trees. It is not only because they may block sunshine. You also do not want falling debris (dead branches) damaging your panels.

Accessibility and Utility Supply

A greenhouse is very much like a grow tent, except that it is placed outdoors where you can take advantage of the sun – mostly. Other than the marijuana seeds and consumables – soil, for example, or nutrients and others – you may also want to check accessibility to utility supplies.

Ideally, your greenhouse should be near the electrical supply. You need to power lamps and other equipment you installed. It should also be close to the water supply. At the same time, be mindful of where excess water goes.

Greenhouse Accessories

A greenhouse is basically a structural frame plus covers or panels. More or less, these are the accessories that merit your consideration in the aid of growing marijuana plants.

Lighting. If you live in a region where it can get too cold or daylight hours may not be enough, then you need artificial lights for the plants. On the other hand, you could do away with lighting if you live near the equator where sunshine is plentiful. But if you want to manipulate the life cycle instead of letting nature take its course, install grow lamps to extend the vegetative period.

Fan. Although you can rely on natural air on most days by opening window panels, it may not be enough on other days. For whatever reason, having an oscillating fan inside the greenhouse can help circulate the air. You’d also find it easier to manage the temperature if it is too warm.

Heating System. If you are in the northern regions, or anywhere where it is cold, you may have to use a heater to keep the plants from freezing to their demise.

Pathogen Control. In warm, humid places where there are also heavy rainfalls, moisture inside the greenhouse might become an issue. That makes for an environment that is conducive to the growth of mold and mildew. A sulfur burner is helpful as it melts sulfur at the right temperature, which leads to sulfur particles landing on surfaces that prevent fungi from growing.

What Greenhouse Kit Should You Buy?

Again, there are plenty of options and configurations. But here are a couple of the best greenhouse kits that you can use for marijuana plants.

1. Palram Applications Hybrid Glazing Greenhouse

The Hybrid Glazing Greenhouse is a marriage of cutting-edge technology and beautiful design. It doesn’t matter where you live – hot, cold, humid, or dry locations. This long-lasting shelter is a fantastic home for your marijuana plants.


Virtually unbreakable combined polycarbonate panels. The twin walls are flexible, impact-resistant, and protect your plants from intense sunlight exposure. Still, it allows 80% to 90% light transmission while blocking 100% UV rays. These panels can last a long time, do not fracture nor turn yellow or opacify.


The frames, made of aluminum, are meant to last for an extremely long time. Besides being rigid, they are also resistant to rusts. At the bottom, the use of a galvanized steel base adds to structural stability.

Other Features:

This greenhouse kit has a sliding assembly system. On the roof, there is a window you can open and close for ventilation. It has gutters and gutter heads that allow you to collect water for a sustainable irrigation system. The hinged door can be configured as a right or left-hand door.


  • Wind resistance: 90km/hr | 56ml/hr
  • Snow load: 75kg/m² | 15.4lbs/ft²
  • Light transmission: 82%
  • Polycarbonate roof panel: 4mm
  • Polycarbonate wall panel: 0.7mm
  • Sizes: 6′ x 4′, 6′ x 6′, 6′ x 8′, 6′ x 10′, 6′ x 12′, and 6′ x 14′

2. Grandio Greenhouses Element

The Element greenhouse by Grandio comes in three sizes – 6′ x 4′, 6′ x 8′, and 6′ x 12′ – and should fit your garden nicely. Although it is the most affordable product line of this brand – the others being Elite and Ascent – it does not compromise quality. In fact, the company is throwing in a lifetime warranty on the frame and 10 years on the panels.

Basic Kit includes:

  • 10mm twin-wall polycarbonate panels
  • Roof windows
  • Rain gutters

Premium Kit includes:

  • 10mm twin-wall polycarbonate panels
  • Roof window
  • Rain gutters
  • Auto roof vent openers
  • 1 pack of 10 plant hangers
  • 1 trellis kit
  • 1 drip kit
  • 1 Brillianize cleaner with cloth 8oz

Grandio Element greenhouses utilize heavy-duty powder-coated 1.6mm aluminum frames and 10mm twin-wall panels made of polycarbonate. It has nearly 6′ tall sliding doors, includes a roof vent, and is made to last a long time. The A-shape frame combines durability, functionality, and aesthetics.

It ships with a standard flat-mount base for installing a concrete slab or wooden deck in a fenced-in setting. But if the greenhouse is going to be placed in a windy or harsh environment, then you can order the optional powder-coated steel base kit. You also can choose anchors for soil, concrete, or wooden decks.


  • Panel: 10mm twin-wall UV-protected polycarbonate
  • Frame: 1.6mm powder-coated heavy-duty aluminum
  • Door: 27″ bind-resistant sliding double-doors
  • Latch: Easy-latch doors with double-ball catch
  • Tools: Included
  • Hardware: Stainless steel nuts and bolts
  • Gutters: Built-in rain gutters
  • Ventilation: Roof vent with adjustable manual openers/latches

Growing Weed in a Greenhouse Gives You the Best of Both Worlds

Think of growing weed in a greenhouse as growing the plants indoors. You can control the environment while keeping pests and predators away. The enclosed space also minimizes pathogens. But because it is outdoors, your plants grow under the best source of light – the sun. Nothing beats the mighty sun when it comes to providing the complete color spectrum that fuels photosynthesis and growth. And while nature nourishes, you are also not spending a dime for electricity the way you would if you had to rely on artificial lights.

Growing marijuana in a greenhouse also gives you flexibility – that is, if you choose one that has room for other equipment. Some of these could be necessities needed to control the climate. Others, such as artificial lights, could be a means for you to manipulate life cycles.

With all the possibilities growing marijuana in a greenhouse provides, there is no reason not to consider setting one up in your garden. As long as you have enough space and it would not be a problem with neighbors or the law, go ahead. Pick one.