Posted on

growing cannabis seeds in a greenhouse

Growing Marijuana in a Greenhouse: What Are the Benefits?

Greenhouses are a great, inexpensive way to cultivate cannabis. They harness the power of the sun, provide a warm climate, and protect gardens from harsh environmental conditions.

They also allow for year-round cultivation, climate control, and a controlled exposure to sunlight. What’s more, they’re cheaper than growing indoors and produce a more consistent product than fully outdoor grows.

How Does a Greenhouse Work?

Solar radiation (energy from the sun) passes through the transparent walls of a greenhouse and heats up soil and plants, keeping a greenhouse warm even when the outside air temperature is cold.

In turn, soil and plants release energy as infrared radiation, which can’t escape the greenhouse, so the trapped heat warms the air.

On a hot day, you experience the science behind a greenhouse when getting into a parked car that has been left in the sun.

This greenhouse effect opens up the door to year-round cultivation, but cannabis still needs light from the sun in addition to the warmth that a greenhouse provides.

Recreating the Cannabis Life Cycle

Cannabis generally goes in the ground outside between April and July, when the sun is out for most of the day. This keeps plants in the vegetative stage.

Once cannabis starts getting 12 hours of light or less, it’ll start flowering and producing buds. This happens outdoors at the end of summer, when days start to get shorter.

Advanced greenhouses can allow you to grow year-round by controlling light. They can provide supplemental lighting when it’s too dark outside and they can block out all incoming light if it’s too light outside.

Advantages of Growing Greenhouse Cannabis

Lighting Control

Supplemental lighting allows the grower to extend the hours of daylight and to improve the quality of light on overcast days. This will give you more control over the vegetative state of your plants.

Weather and Climate Control

Controlling your greenhouse climate is essential to producing a quality product. Some greenhouses have windows or paneling that can be opened or removed to either allow for wind circulation and to cool plants, or to trap in heat.

Greenhouses also provide cover for your plants, as heavy rains will damaged them and cause them to rot if too much moisture is trapped inside the buds. Some can also have dehumidifiers, heaters, air conditioners, and fans, all of which will also regulate the climate.

Manipulating Life Cycles

A common practice among greenhouse farmers is to run cycles of plants known as “light deps”—short for “light deprivation”—during the summer season. By cutting off the amount of light a cannabis plant gets before the end of the season, you can trick it into flowering early. This will allow you to pull a crop early, which is key if you live in a climate that gets cold and wet early in the fall—you’ll want to harvest before the rain sets in and causes your buds to get moldy.

If you want to continue growing cannabis through the fall and winter, you will have to lean more heavily on supplemental lighting and heaters.

During the winter solstice in Seattle, for example, there’s less than nine hours of daylight, and the light that is available is low in the sky and poor for growing. This light and energy will still help heat the greenhouse, but you would need to use supplemental lighting to extend the hours of light in the day in order to get a quality product.

Energy Conservation

The ability to control light and keep the climate stable will allow for year-round cultivation just like indoor growing. But growing outdoors and with a greenhouse is a lot more inexpensive than growing indoors, and you’ll save a lot of money on electricity costs. Even if you need to supplement light in a greenhouse, it’ll still be cheaper than the energy needed to power an indoor operation.

Grow Weed Easily And Successfully By Building A Greenhouse

Building and growing in a greenhouse aren’t as difficult as you might think. Read on to discover the benefits, and the ideal greenhouse setup for you!

A greenhouse provides the best attributes of both indoor and outdoor cannabis growing. But don’t think that building your own greenhouse means a difficult or expensive endeavour. A simple greenhouse doesn’t cost much, and all you need is a suitable space in your garden or on your balcony to get started growing cannabis like a pro. Read on to learn how to grow cannabis easily, and successfully, in your own greenhouse!


For many growers, a greenhouse is an easier and more practical option than an indoor grow room. It provides all the perks of outdoor cultivation, like natural sunlight, yet offers protection from the elements, insects, and animals.

For growers in cooler regions of the world, a greenhouse can also provide a longer growing season. You can, for example, plant your seeds earlier each season, as well as harvest later if need be—and you don’t need to worry as much about cold temperatures and rain. You also have the option to heat and cool your greenhouse, supporting ideal conditions for growing top-quality weed rivalling that of warm-weather growers.

Aside from offering protection from wind, rain, and frost, a greenhouse has a lot of other benefits. For example, you can equip your greenhouse with artificial lighting to take advantage of grow lamps and natural sunlight. This way, you can control a plant’s vegging and flowering phases as if you were growing indoors. Moreover, if you set up a small greenhouse on your balcony or terrace, it can be a good way to keep suspicious odours and noise from being an issue indoors.


You can grow all types of cannabis in a greenhouse with great success. Here are some specifics about autoflowers versus photoperiod plants:

• Growing autoflowering cannabis

Let’s start with autoflowering cannabis. The features that make autos popular among indoor cultivators are largely the same among greenhouse growers. This includes their compact size, fast growth, and, of course, their ability to flower based on age, rather than light cycle.

When it comes to size, autoflowers often max-out at a metre or less in height, with some cultivars reaching only 50cm. This makes them excellent candidates for smaller greenhouses, such as those on a balcony. Moreover, some greenhouse growers like that you can cram several autos into a relatively small space to increase yield.

See also  how many cannabis seeds in a 10 pack

The short life cycle of autoflowers is a key advantage to growers of all types. Taking 60–70 days from seed to harvest on average, this is extremely short in comparison to feminized photoperiod strains, which take this long just to flower. In a greenhouse, this feature allows growers to reap multiple harvests per year and per season.

In terms of light cycle, autoflowers allow growers to plant at basically any time of year, as long as there is enough artificial light to support robust growth.

• Growing feminized (photoperiod) cannabis

When growing feminized photoperiod strains, you have the choice to use exclusively natural sunlight, or you can supplement with artificial light. If you grow in natural sunlight only, your plants will essentially have to follow the regular outdoor grow season schedule. At the end of summer, plants will start to flower, and then you can harvest sometime in autumn. Luckily, the controlled conditions of a greenhouse can support flowering deeper into fall, which is a major benefit for sativa growers especially.

By supplementing your grow with artificial lighting, however, you no longer need to follow the outdoor grow season if you choose. Instead, you can calculate an ideal sunlight/grow-light schedule to capitalise on the free power of the sun, while benefiting from the control offered by grow lights.


Given ideal environmental conditions are met, your plants can, in principle, grow just as large in a greenhouse as they can outdoors. It’s not uncommon for cultivators to harvest 2–3m-tall monsters, or even taller. Of course, this all depends on how much space you have in your greenhouse and how large of a plant you want to deal with. Even if you don’t have a super tall space, you can still potentially grow sativas and other lanky strains using training techniques. Simple LST can keep vertical growth in check, and techniques like topping can help to boost yield while breaking apical dominance. You can also keep height in check by skipping the vegetative phase and initiating flowering right away.


You can build and purchase greenhouses of virtually all sizes, from simple mini-greenhouses to custom-built, full-fledged extensions for your home. You can find greenhouses consisting of a transparent PVC sheet over a metal or wooden frame, some that use polycarbonate plastic panels, and others made from glass. Some types of greenhouses are designed to be situated against a wall of your home so the heat keeps the greenhouse warm.

A simple walk-in greenhouse with a metal frame and a sturdy PVC sheet with a zipper door can be purchased for little money. These are great if you’re on a budget and/or you don’t want to go all out building a greenhouse from scratch.


Where you place your greenhouse is very important, for a number of reasons:

The location of your greenhouse will ultimately determine how much sun your plants receive. Obviously, you don’t want to place your greenhouse behind your house in the northern part of your garden where your plants never get any sun. The best location is the south or southeast side of your house.

On the other hand, if you live in a hot and sunny climate like the Mediterranean, you may want your greenhouse in a shaded location. Likewise, if you plan to mostly use artificial lighting, it matters less where you greenhouse is located in relation to the sun.

However, you will want a power outlet nearby if you plan to equip your greenhouse with grow lights, fans, and/or an exhaust system.

• Shelter from wind and rain

You want a location for your greenhouse that isn’t exposed to strong wind and weather. A sheltered area behind your house, or somewhere tucked away on your terrace or balcony, can be optimal. If you plan to build a greenhouse in a less sheltered place, like in the middle of your garden, this will need to be professionally constructed and anchored in place. Otherwise, a strong gust of wind could be enough to blow your greenhouse away.

• Water and drainage

Another important consideration: Is a water connection and drainage nearby? You don’t want to be lugging buckets of water to your plants or draining the runoff into the middle of your garden. Having water and drainage available is also important if at some point you decide to automate your system or implement hydroponics. Some hydroponic systems may require changing the tank every few weeks. If your greenhouse is on your balcony and there is no way to empty or fill the tank, short of carrying the tank into your house bathroom, this could be an issue.


Supplemental grow lights aren’t just good for greenhouse growers in regions without much sun; they can be beneficial for growers in any location. Even in sunny climates, an additional grow light can get your plants through the cloudy days. Plus, if you live somewhere with a chilly climate, a powerful HPS light can support adequate temperatures for your plants.

Another big benefit of having a grow light in your greenhouse is that you can extend the hours of light your plants receive. For example, you can use the lights to provide your vegging photoperiod plants with 18–20 hours of light, even when natural daylight hours would be much shorter. This allows you to grow your plants all year long—plus it will greatly increase your yield.


In addition to artificial light, you can also install a darkening system in your greenhouse. Such systems usually consist of automated blinds or a curtain on a timer, and allow you to induce and support flowering even when the days are long and sunny. With a darkening system, you are able to simulate the shorter days in fall. Put your plants under a 12 hours on, 12 hours off light cycle to initiate flowering. Pro greenhouse growers time their light-dark cycles so they can plant and harvest cannabis all year long!


At times, a greenhouse may also bring with it some issues. One of them is the potential for the space to get extremely hot and humid, and this can happen quite quickly depending on the climate and positioning of the structure.

See also  autoflower cannabis seeds california

When the sun is shining into your greenhouse, temperatures can rise to dangerous levels for your plants. In some cases, this may only cause plants to grow slower, but once temperatures exceed 40ºC, fatalities can occur.

As such, you want to make sure that your greenhouse has optimal ventilation and cooling, and you may want to consider artificial lighting with less heat output, like LEDs.

If you build a simple PVC greenhouse, you can make it so the windows open during the sunny months. If the greenhouse doesn’t have openings, you can easily cut the plastic sheeting to provide some nice airflow. More elaborate greenhouses can be made with windows that open and close, and some are even automated.

Aside from rain, humidity is rarely an issue outdoors as there will always be a nice breeze. But in a greenhouse, excessive humidity can quickly lead to an unhealthy growing environment that facilitates mould and bud rot.

To keep your plants happy, make sure there is good air circulation in your greenhouse. Some of the above methods for temperature control will also help keep humidity in check. You could also leave the greenhouse door open for periods of time, and again, can cut holes into the sheeting where necessary.

Likewise, a simple oscillating stand fan gently blowing air across your plants can prevent pockets of stagnant, humid air from forming. You should also keep a thermometer and hygrometer in your greenhouse. Just keep an eye on these things and your cannabis will thrive!


Do you desire the yield and majesty of outdoor cannabis, and the control and safety offered by indoor grows? Consider a greenhouse. Using a variety of different materials and building methods, you can customise a greenhouse to suit your needs and budget. You can build out a 220cm x 120cm walk-in greenhouse with a sturdy PVC cover over a metal frame for under €100. And once you’ve harvested your first crop of greenhouse cannabis, you can always upgrade to something more elaborate to push your plants’ potential even further.

How To Grow Cannabis In a Greenhouse

Despite the fact that the popularity of cannabis is on the rise what seems like everywhere these days, many enthusiasts and consumers find themselves in places without either dispensaries or the legal framework to safely obtain some quality buds, which would partially explain the exploding popularity of domestic cultivation. This is a reliable and (relatively) inexpensive way of ensuring access to your medicine, but new growers are faced with a slight dilemma: what is the best method to cultivate cannabis at home and how do I go about it?

The three fundamental ways are: outdoor as mother nature originally intended it, indoor as resourceful humans have discovered (and perhaps even perfected) or in a greenhouse as a combination of the first two. Multiple factors can play a role in determining which setup is best for you, including things like experience, budget, security, available resources, etc., but in terms of producing an abundant and quality end product, we’ll focus on the greenhouse method as it seems to provide the most bang for your buck without the exorbitant price tag of indoor growing and without the risk of being at the mercy of mother nature’s whims (floods, droughts, pests, etc.).

Why Grow Cannabis in a Greenhouse?

Growing in a greenhouse provides several advantages over both the indoor and outdoor method without breaking the bank, so regardless of your budget, you can produce outdoor amounts of cannabis with indoor quality buds. So what makes greenhouse growing special?

First of all, it provides the basics that a cannabis garden needs: air, light, and warmth. They take the sun’s energy so that plants can conduct photosynthesis and since they can be easily opened up, they also provide plenty of carbon dioxide for plants to breathe in, something that is often artificially supplemented in indoor setups. Since greenhouses get their heat by trapping the sun’s radiation during the day, this means that they can also be used during the winter, though light supplementation might be a good idea if there are only a few hours of daylight available that time of the year. The radiation released by plants stays in the greenhouse, keeping the air at a steady temperature. What this means is that you can grow year-round and are not tied to a single harvest as you might be with a traditional outdoor grow.

Another advantage that greenhouses have over growing outdoors is the element of protection. Without any form of protection, be it a glass roof or a plastic tunnel, plants are subject to whatever nature throws at them in the form of dangerous precipitation such as hail or heavy rain or in the form of pests and predators (including the human variety) that can quickly destroy an entire crop if left unchecked. Not to say that greenhouses are a 100% guarantee against anything bad happening to your crop, however the control over your crop and the resulting yields that a greenhouse provides are unmatched by the other two options. With the added protection against storms, greenhouses also allow for an extended growing season, which means that equatorial sativa varieties can be fully mature without having to rush a harvest before the winter. This allows not only for more cannabis year-round, you can also diversify your strain portfolio.

Greenhouse Growing Basics

It may seem a little complicated at first and some greenhouse setups are on the fancy, technologically advanced side of things, but the premise is quite simple: use the sun’s natural (and free) energy to provide light to your plants and heat your grow space. With the greenhouse’s glass or plastic covering, heat and humidity get trapped and the space stays warm and humid. These conditions can then be controlled by the grower as needed. The space can be ventilated to maintain a certain humidity or to reach a specific temperature.

Watering and feeding are the responsibility of the grower as well since the space is protected from precipitation. Depending on the circumstances, it might be necessary to supplement your garden with artificial light, particularly if growing during the winter when there is less natural light available. On the flip side, tarps and/or blackout screens may be required if you are using the light deprivation technique to have multiple harvests and need to switch to a 12-hour day/night cycle quickly.

As is the case for cannabis plants in general, you will also want to start your garden with some good genetics, in other words quality seeds from a trusted breeder or seedbank. With an extended growing season, this means that you can also grow a range of sativas with a frustratingly long flowering time and not have to worry about a surprise snowstorm in late fall/early spring.

See also  sunset shortcake seeds

In addition to good genetics, your garden will need a reliable medium to flourish and in the case of greenhouse growing, you have two options to choose from: pots or directly in the ground/raised beds. The benefits of growing in pots include increased mobility for your plants if they need to be moved for whatever reason and absolute control over what goes into the soil, namely water and nutrients. Much like indoor setups, this can produce top quality buds with impressive terpene profiles thanks to the personal attention given to the garden by the grower. However, with this method, growers will have to attend to their garden more regularly as plants that are confined to smaller pots will be a little thirstier and hungrier more frequently than those growing directly in the ground.

If you do decide to plant directly in the ground or in raised beds, the additional space for plant roots to grow will help with water and nutrient conservation and growers will be able to check up on their garden with less frequency, in some cases even up to two weeks between watering/feeding. If using an automated watering/feeding setup, growers will have even more free time to focus on other aspects of their garden.

Maximizing Your Greenhouse Setup

There are many good reasons to start growing in a greenhouse, but one of the biggest arguments for doing so is the ability to manipulate the plant’s life cycle. As mentioned above, light deprivation is a technique that is growing in popularity as it allows for multiple harvests in one growing season. The idea is to trick the plants into thinking it’s flowering time by cutting off light for 12 hours until they’re ready for the chop. While still possible with outdoor plants, it is much easier to pull a tarp or other covering over your roof than to do so with monstrous tree-sized plants growing directly under the sun.

If growing in the winter, you can still grow plants with supplemented light, thereby extending your growing season even further. Another trick that can be used to get several harvests in one season is the use of autoflowering varieties. Since autoflowers are not photoperiod-dependent, they will automatically enter flowering and finish faster than they’re photoperiod cousins, which means no light deprivation will be needed. If you get your hands on a big-yielding autoflowering variety, you can produce yields that will rival the quality of photoperiod strains in half the time.

Greenhouse Safety & Security

Greenhouses can be of any size and therefore are suitable for all levels of growing, whether you’re a small-scale novice or an experienced commercial grower, however a few things should be taken into account regardless of the scale of your garden or your experience. Security and privacy are going to be top priorities for many growers, particularly in places where cannabis is still illegal.

Secure your greenhouse

A greenhouse will provide a basic level of privacy and security for your garden, however in this case you cannot be overcautious. Installing additional locks, cameras and alarms will make it that much more difficult for burglars, vandals and the like to get to your crop. Having a greenhouse in an area difficult to access physically is another theft-deterrent, though not every grower will have that option.

Odor control

Another security issue to take into account is odor control. Towards the end of the cannabis life cycle, fully flowering plants will produce a smell noticeable from far away, so odor control is a must. In-line ozone generators have been used successfully in the past and many companies now offer various products such as blocks, sprays and gels to neutralize the pungent smell of cannabis, so finding the right type of odor control has become that much easier.

Consider heat and humidity

Another aspect to consider when choosing a greenhouse is ventilation. During the warmer months, things will get hot and muggy inside, which means there will be the potential for mold to develop so proper airflow for your plants is key. Some greenhouses come with panels where you can open the sides of your grow space to let fresh air in. In other cases, air has to be pumped through with exhaust fans.

Keep your greenhouse clean

As with any setup, regardless whether indoor or outdoor, cleanliness is also a must. By keeping your greenhouse clean, you will keep away pests, mold and other pathogens that can quickly destroy an entire crop.

Types of Greenhouses

Not all greenhouses are built the same, though they share a lot in common. The market for greenhouses is expanding thanks to the loosening of cannabis restrictions and different growers will have different needs. Some of the more common greenhouses used these days include the lean-to (which shares a wall with another structure to provide support for the roof), even-span greenhouses (which include tunnel-like hoop houses), uneven-span greenhouses, ridge-and-furrow greenhouses as well as retractable roof greenhouses. Some companies have even installed light-deprivation elements/tarps in the roof mechanism to make light dep all the more convenient.

Different materials can also be used for the covering or glazing. Glass is generally regarded as the best material for growing in a greenhouse, though other popular materials include polyethylene sheets, polycarbonate structured sheets (which are for good light transmission), acrylic structured sheets and fiberglass sheets. All of them have their advantages and disadvantages, so choose according to your needs as well as your budget as the costs can greatly vary as well.


Growing in a greenhouse doesn’t have to be complicated or expensive at all. With the right amount of research and planning, you can design a grow space that will consistently provide high-quality yields that will rival any indoor setup but with the cost, time and energy-saving benefits of growing under the sun. It can be challenging at first, but there are too many arguments not to give it a try. Are you ready to take your growing skills to the next level?