Growing Weed in a Greenhouse

The current increase in people growing their own cannabis has given rise to a greenhouse growers community that is rapidly expanding. For some, it is easier to grow cannabis seeds in a greenhouse than it is create an indoor grow room. Greenhouse growers find it less complicated than growing cannabis seeds outdoors.

Greenhouses not only guard against harsh weather conditions, pests, and predators, but they also allow for an extended growing season. You can plant your cannabis seeds a few weeks earlier than if you were growing them outdoors. Plus, the greenhouse protects your plants form bad autumn weather during harvest- giving you a better chance of a safe harvest.

One of the many benefits of growing cannabis seeds in a greenhouse is that it allows growers in northern European regions to grow high quality cannabis with either feminised seeds or autoflowering seeds.

Cannabis seeds and greenhouses

If the temperature outside plummets, greenhouses can be warmed to keep your plants healthy. This also enables you to begin growing cannabis indoors sooner than if you were gardening outdoors. For more helpful tips on getting started, read our germination guide.

Greenhouses provide a controlled environment, which is perfect for cannabis cultivation. Home-grown weed is not only more affordable but also fresher and higher in quality than store-bought options. Greenhouse-grown cannabis tends to be more potent as well since growers can select strains that are suited for their desired outcome.

Autoflower seeds in greenhouses

A greenhouse allows autoflower plants to thrive and produce large harvests of over 100g (dried buds), as it safeguards them from harsh weather conditions that can occur–particularly in early spring and autumn.

Since autoflowers have a shorter life cycle of around 100 days in a greenhouse, it’s important to optimize the growing conditions and environment to get the best quality and quantity harvest possible.

Not only does a greenhouse strengthen your plants against unfriendly weather conditions, but it also provides extra defense against pests. Greenhouses are thus an excellent tool for cannabis growers.

Feminised cannabis seeds and greenhouses

Feminized seed varieties are optimal for growth in greenhouses. Usually, they will continue to grow until the days start shortening, and then September or October (depending on your specific variety) will show first signs of bloom. In the northern hemisphere, it is ideal to plant feminized seeds from April through October inside a greenhouse.

By germinating and planting the seeds in a heated greenhouse around March/April, you can get an earlier start than usual. That’s because greenhouses offer more protection from bad weather conditions early on.

By nurture your plants in a greenhouse, you enable them to grow larger than would be possible if they were outdoors without a shelter. Many growers of photoperiod feminized seeds routinely harvest sizable crops of dried buds from individual plants. Plants can easily reach 2-3 metres tall and just as wide under these conditions. Since greenhouses also protect your plants from the autumn/winter storms, this type of setup allows the willing gardener to grow a broader range of later blooming cannabis seeds than is possible outdoors.

Greenhouse cultivation of cannabis seeds

There are two main types of greenhouse growers: those that grow their cannabis plants in plant pots and those that grow them directly in the ground. Plant pots can be easily moved if they need to be, for example if visitors, extreme weather or other problems are present. But plant pots will need more frequent watering and occasional feeds. A large cannabis plant in a 10 litre container will need watering daily during very hot weather, which could create an issue if you’re away from your plants and unable to water them regularly..

On the other hand you may experience less issues with humidity, especially if your greenhouse floor is covered with paving slabs. Growing in containers also allows the grower more control over nutrient addition.

You can grow cannabis in soil, coco fibre, or any other medium inside a greenhouse. Some greenhouse growers even have automatic feeder systems for their plants (e.g. AutoPot, Blumat, dripper systems).

Plants that are rooted directly in the ground obviously can’t be moved, but will survive well even when you are away for a week or two. There is less need to worry about daily watering. If your greenhouse contains good quality moist soil then your cannabis plants will establish an extensive root network which will support a large plant with heavy yield potential. However, if the ground under the greenhouse contains poor quality soil then remove it and replace with good quality soil before growing plants in it. Serious greenhouse growers will dig in plenty of manure and compost at the end of each growing season to ensure optimized soil quality for the following years crop. One advantage of rooting your plant directly into the ground is that you can grow very large plants with unrestricted root space. It’s one way to get XXL harvests. If you find that a single cannabis plant is taking up too much space in your greenhouse, you can try low stress training to tie down the taller branches. In extreme situations, some growers have even had to remove some roof panels from their greenhouse if the plant grows uncontrollably. Alternatively, plants which are rooted directly into the ground can be grown using automated feeding systems such as dripper systems.

Greenhouse overheating. Protecting your plants from extreme summer heat

A greenhouse might superheat in mid-summer, which then creates difficult foliage conditions and puts the root system under duress–particularly during a heatwave when temperatures could surpass 30 or 40 degrees celsius. Not ideal for optimum cannabis growth. However, any dedicated grower can find ways to circumnavigate these challenges.

To keep your greenhouse at a comfortable temperature, attach windows that open when it’s hot and close automatically as the temperature cools. This will release the hot air quickly. You can also prop open a door to allow a cooling breeze to flow through. If you’re worried about pests, get a door made with panels of fine wire mesh that will let air in but keep insects out.

Sophisticated greenhouse growers have watering systems in place to simplify and even automate water delivery. If the greenhouse is not in an entirely private location then it might benefit from a coat of white shading paint. This is sold in garden centres and used to protect greenhouses from overheating on the hottest summer days. For the cannabis grower this shading paint also stops people seeing what is inside your greenhouse, but green plastic plant mesh and tomato plants have also provided excellent cover for many generations of greenhouse growers.

On a sunny spring day, you’ll immediately notice how quickly greenhouses warm up. This allows growers to start their favorite cannabis seed plants earlier in the season than if they were planted outdoors. Additionally, using greenhouse heaters available at most garden retailers can help reduce the effect of cold nights on your crop. Larger plants and improved harvests are benefits of an earlier growing season!

When the days start getting shorter in the summer, this signals to outdoor-grown cannabis plants that it is time to flower and produce female buds.

How large do cannabis plants get inside a greenhouse?

If the greenhouse grower can get good soil for his plants, and if he starts with high-quality cannabis seeds, then his plants can reach their full potential by the end of the season. Many growers have seen their plants fill small greenhouses and produce hundreds of grams of top-quality weed per plant. Though good quality cannabis seeds may cost more upfront, they will save you money in the long run.

As mentioned earlier, some greenhouses come with windows that can be opened to let any particularly large plants grow out. But a safer option is to use cord to ‘tie down’ the plants if they do start growing massively. The photos above depict what can happen when an especially productive strain starts turning into a tall bush resembling a small tree. The plant simply becomes too tall for the greenhouse; however, the soil conditions, temperatures and excellent care resulted in a plant that was thriving as if it were in the jungle rather than in a garden located in northern Europe.

Extravagant growth like this happens rarely with cheap cannabis seeds that are grown in poor quality conditions and badly prepared soil. To grow a monster plant, you need to start with properly dug, well-prepared soil that is rich in nutrients. As the pictures show, large cannabis plants can simply outgrow the greenhouse when they are given the right conditions, resulting in a heavy harvest for the grower. The Dutch Passion Shaman variety was bred specifically for outdoor/greenhouse conditions. The Shaman strains comes from very potent skunk and purple skunk parents and is known for its vigorous growth. In 2006, it won the Dutch Passion photo contest award after growing into a bush that was 3 metres tall and 2 meters wide. The grower in this case had to remove a pane of glass from the greenhouse because his plant got so big. Since security wasn’t an issue, he was able to harvest a lot of high-quality cannabis despite the size problems he ran into.

Cannabis genetics and greenhouse growing

Remember that some plants can grow as wide as they are tall, especially if they have plenty of sun and good soil. A few seeds could provide a year’s worth of medication or recreational weed, so regard the cannabis seed as an investment. With cannabis seeds, you don’t have to settle for anything less than the best. For some of the highest-quality options, check out the Dutch Passion website. Proven varieties that grow well in greenhouses located at northern latitudes include Shaman, Durban Poison, Passion #1, Frisian Dew and Frisian Duck. These varieties have been used by numerous growers over many years and they never fail to meet stringent standards for potency, quality, pest/mold resistance and vigour. Growing these feminized seeds in a greenhouse will give you excellent results every time.

Early flowering using a ‘darkening system or extending your growing season

Some growers have a “darkening” system in their greenhouses. This uses dark blinds or curtains to make it black inside, even when it’s sunny outside. Growers do this to simulate short summer days and ‘force’ the plants to start flowering sooner than normal. Even though this costs extra money, Bud production will be accelerated . The grower just has to use the blinds reduce daily light exposure to 12 hours (or less), and then the plants will respond by flowering.

In addition to giving the gardener year-round production, greenhouses also enable growers to extend their planting season. With proper ventilation, cold sunny autumn days become warm and comfortable inside a greenhouse, allowing plants to ripen properly. Pests are typically easy to control in a greenhouse due its structure that is impervious to pests. Overall, it is great and simple way of growing produces when taking all factors into account.

Nowadays, people not only grow cannabis seeds outdoors but also in polytunnels for the same reasons as greenhouses. Polytunnels protect against bad weather conditions, fortify plants, and allow for a longer growing season while maintaining privacy for the growers. Thanks to their diverse size range, there’s a perfect match for any type of gardener out there.

Growing cannabis in a greenhouse is more cost-effective than indoor growing because you wouldn’t have to spend as much on grow lights and electricity. All you need to get started with greenhouse growing are some seeds and substrate. Plus, the sun provides free energy for your plants!

Greenhouse grown cannabis versus outdoor cannabis

With a greenhouse, outdoor cannabis growers can eventually upgrade their crop to produce more potent strains with higher THC levels and better terpene profiles. Regardless of whether you have a large commercial budget or are limited to growing just one or two plants in a small greenhouse, the quality improvements offered by this change will always be important and appreciated. By growing in a sheltered environment, cannabis plants grown in greenhouses are healthier overall due to optimized conditions. Greenhouses provide your plants with the best possible chance of survival by protecting them against pests, disease, extreme weather conditions, and more. By growing your plants in a greenhouse, you can create a warmer environment for them to thrive in. As a result, your plants will often mature under much better conditions than they would outdoors.

Where to locate your greenhouse?

Security and climate are the two main things to consider when determining the location of your greenhouse. You don’t want your neighbours or passersby to be able to see or smell your crop, so pick a spot that makes it difficult for them to do so. In terms of climate, if you live in a cool area, locate the greenhouse where it will get maximum sunlight throughout the day. If you’re in a hot desert climate, on the other hand, placing the greenhouse under some trees would be ideal since they would provide shade during midday heat in summertime. If you’re a greenhouse grower in the Mediterranean, it might be beneficial to put your greenhouse in a cooler, more northern part of the garden where there is some shade. Keep in mind that when temperatures get up to 40-45ºC, they can become damaging.

If you don’t want to make multiple trips back and forth from your house to the greenhouse carrying a watering can, consider connecting a hosepipe/water source near your greenhouse.

Greenhouse options for cannabis growers

Greenhouses come in an array of prices and sizes. The more affordable ones are made with a flexible transparent plastic mesh that goes over a small metal or pole frame. These can cost as little as 20 euros but they’re only big enough for one plant. Some greenhouses are designed to stand against an exterior wall of the house. If you have a porch, balcony, or any outside area accessible to your home, consider getting a greenhouse! They come in all shapes and sizes for different prices too. If you are especially worried about safety or have small children often running around, go for one that has polycarbonate panels instead of glass (they’re unbreakable). Trust me–there’s definitely a perfect option out there waiting for you.

Growing cannabis in a greenhouse: Easy and effective cannabis growing

By growing cannabis in a greenhouse, you can provide for your own cannabis needs relatively easily and inexpensively. Greenhouse cultivation appears to be burgeoning among passionate growers all over the world.

Each year, the more professional greenhouse grower will introduce new soil/fertilizer and take care to keep their greenhouse clean and tidy in order to reduce potential for pests and disease. Some growers use fencing and shrubs placed strategically around the perimeter of their greenhouses make it inaccessible to trespassers or unnoticed from passersby. Greenhouses are cheap—you can buy a small plastic one for less than a hundred euros. Even cheaper models with just a plastic cover are available. You can find them everywhere, and they come in any size or shape you might need- all while staying within your budget. Some newer polycarbonate greenhouses are even opaque, providing privacy the instant you step inside and have lockable doors. What more could you ask for right in your backyard? Just remember that low quality cannabis seeds will never produce high quality marijuana buds, no matter how well you take care of them during the growth process. Invest in the best cannabis seeds from a reputable company to ensure premium product, and then enjoy growing it yourself– greenhouse included!