How to Grow Cannabis in a Greenhouse: A Guide
Growing cannabis in a greenhouse is an effective cultivation method that combines the perks of outdoor growing with those of indoor cultivation. Learn all about it below!
Learn to grow cannabis in a greenhouse.
Growing cannabis in a greenhouse is ideal because it combines the benefits of outdoor growing with those of indoor cultivation. In this guide, we’ll show you how to do it, offering tips and advice as we go along. If you don’t have a greenhouse yet, and want to build one, we can show you how to do that, too.
WHY GROW CANNABIS IN A GREENHOUSE?
Maybe you’re wondering why you’d want to grow weed in a greenhouse, as opposed to growing indoors in a tent or having an ordinary outdoor grow in your garden. Let’s look at the advantages of greenhouse cultivation over other growing methods.
YOU CAN EXTEND YOUR GROWING CYCLE
You can extend the cultivation period into the fall and winter seasons simply by adding more light during cloudy days, and progressively keeping them on longer to compensate for shorter daylight hours. Likewise, if you want to start a new grow before the end of winter, you can add a low-powered light to supplement natural daylight.
PROVIDES THE IDEAL MICROCLIMATE FOR GROWING CANNABIS
A greenhouse environment can sustain higher average temperatures than chilly open fields or gardens. Plus, during cold or hot seasons, you can heat or cool a greenhouse if needed. Even without a heater or cooling system, a greenhouse will provide a more consistent range of maximum and minimum temperatures, without the extremely dry and hot conditions typical for indoor grow rooms. A more consistent microclimate means healthier plants and bigger harvests.
ALLOWS FOR YEAR-ROUND CULTIVATION
The climate within greenhouses can easily be controlled, for instance by opening windows or installing fans. And, since the walls of a greenhouse keep humidity and heat inside, it allows for year-round cultivation. This control over climate and exposure to light isn’t possible in regular outdoor cultivation.
MORE CONSISTENT HARVESTS
Greenhouse harvests tend to be more consistent over time, both in quantity and quality. This is also why the majority of commercial medicinal cannabis produced today is grown in greenhouses.
MORE ENERGY-EFFICIENT THAN INDOOR GROWING
Since cultivators can take advantage of natural sunlight, growing in a greenhouse is way more energy efficient. You will also have much lower electricity costs compared to growing in a room or tent.
PROVIDES PROTECTION FROM THE ELEMENTS
Unlike outdoor cultivation, a greenhouse protects your plants from the elements. There is no threat of rainfall or storms harming your precious ladies. In addition, a greenhouse prevents scavenger animals from having their way with your crops.
KEEPS PLANTS SAFE FROM DETECTION
A greenhouse allows for discreet growing with a greatly decreased risk of detection. Your plants will be safe and secure, so you can go to sleep without worrying about thieves and vandals.
IT’S NOT EXPENSIVE
Growers don’t need to spend a lot of money to set up a greenhouse. A simple walk-in greenhouse can be purchased for little money, and will do a decent job of housing your plants. Building a DIY greenhouse is another inexpensive option. For a simple grow using natural light and hand-watering, there’s no need for expensive grow equipment.
HOW TO GROW WEED IN A GREENHOUSE?
Growing cannabis in general involves many variables that need to be kept in check. Growing in a greenhouse is no exception. However, differences in methodology from indoor and outdoor cultivation need to be taken into account. Here is a list of steps you can take to run a successful greenhouse grow.
PICK A SUITABLE STRAIN
Cannabis strains differ in how they grow, and in regards to their requirements. The best type of cannabis for your greenhouse setup ultimately depends on a number of factors, including your local climate, available space, and whether you’re planning to use an artificial grow light. Let’s dig in a little deeper:
Autoflowering cannabis is optimal if you’re growing using natural sunlight. As autoflowers don’t require a set light schedule to veg and flower, variations in sun exposure won’t harm your plants or diminish yields as much as photo-feminized plants. This also means you can plant and harvest autos in your greenhouse at any time of year—as long as you support ideal environmental conditions.
Lastly, the smaller size of most autoflowering varieties comes in handy if space is constrained, which is usually the case with small greenhouse setups. To make up for lower yields from smaller plants, you can simply grow more of them in your available space (e.g. the sea of green method).
Growing photoperiod feminized cannabis is also possible in a greenhouse, but comes with some constraints, especially if you’re using exclusively natural light. As these strains flower based on the hours of light they receive, you rely on the seasons to support vegetation and stimulate flowering.
However, you could also set up an artificial grow light on a timer to control your plant’s development. But then you may also need to look into making your greenhouse light-proof. Otherwise, the natural daylight could interfere with your artificial light schedule, causing its own issues.
Another issue when growing photo-feminized plants in a greenhouse is that you may need to train and prune your ladies to prevent them from growing out of contol. Especially if you’re using only sunlight, plants can get tall and spindly, and may require some topping, scrogging, and the like to remain at a reasonable height.
PLAN YOUR GROW WINDOW
With natural light as the main source of energy in your greenhouse, you need to plan your grow window accordingly. Ideally, you want to be ready as soon as daylight hours (and temperatures) start increasing in spring.
Even though your greenhouse will maintain higher temperatures than those outdoors, you should wait until there is no risk of frost before bringing your plants into the structure. Depending on your location and local climate, this may be early or quite late in spring.
Building on the above, you can always germinate your seeds indoors and start nurturing your plants with low-powered CFLs to give them a head start. You won’t need much space for this, and CFLs tend to run cheap. This way, even if the rest of your grow is conducted using sunlight, you can still take full advantage of the outdoor growing season.
MOVE SEEDLINGS TO THE GREENHOUSE GRADUALLY
As soon as your plants get a little bigger and stronger, after about a week or two, you can gradually get them used to their new growing environment. Go easy on them, and don’t move them abruptly from the cosy indoors to the greenhouse. Set them in the structure for just a couple of hours each day and increase over the first few weeks.
This way, stress is reduced and plants can continue to develop without a hitch. Your plants are sensitive, especially at this stage, so don’t use your greenhouse as an excuse to be negligent.
SUPPLEMENT LIGHTING ACCORDING TO WEATHER
One of the great things about greenhouses is that they allow growers to supplement natural lighting with an extra grow light. Stretches of poor/cloudy weather can be overcome without fear of a diminished harvest, and your electricity bill will be vastly lower than if you grow indoors.
Then again, if one is growing in a suitable climate with plenty of sun, a supplemental light may not be necessary. Still, having one at the ready is never a bad thing for a cannabis grower.
USE BLINDS OR COVERS TO FORCE FLOWERING
A greenhouse makes it possible to force-flower cannabis using light deprivation techniques. Elaborate timed shutters could be installed to obscure plants for this purpose, but simple blackout covers or blinds can also do the trick—at a fraction of the price and with much less effort.
In addition to allowing you to flower your weed at any time, blackout covers also serve to prevent cannabis light pollution (e.g. nearby street lighting), which could otherwise interfere with flowering for photo-feminized plants.
PRO TIPS FOR GROWING CANNABIS IN A GREENHOUSE
You want your cannabis to be happy, comfortable, and productive in your greenhouse grow-op. So, what else do you need to know to achieve a great harvest? Check out our pro tips below.
In this article, we cover how to successfully grow cannabis in a greenhouse. Learn the pros of greenhouse weed cultivation and get your own grow started today!
A primer on growing marijuana in a greenhouse
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- Benefits of growing marijuana in a greenhouse
- Buying a cannabis greenhouse
- Growing marijuana in a greenhouse
- Should I grow weed in a greenhouse?
Cannabis cultivation can take place indoors, outdoors, or in a combination of these two venues: the greenhouse . A greenhouse, traditionally fashioned from glass, can be as small as a tool shed or as large as an industrial building. If you have enough space to accommodate even a small marijuana greenhouse, this option may propel your cultivation to the next level.
In this guide, you’ll learn why growing cannabis in a greenhouse can be effective as well as the first steps you’ll need to take to do it.
Benefits of growing marijuana in a greenhouse
The key word when it comes to cannabis growing in a greenhouse is control . A greenhouse provides the ideal meeting point of an indoor and outdoor climate while eliminating the unpredictability of the latter. Periods of rain and wind can wreak havoc on your weed garden, but a greenhouse protects plants from the elements. Likewise, pests, bacteria, and diseases are less likely to invade your plants in the shelter of a greenhouse.
The key word when it comes to cannabis growing in a greenhouse is control. Photo by: Gina Coleman/Weedmaps
A marijuana greenhouse also puts you in control of two primary factors in a successful grow:
Lighting: A greenhouse gives cannabis plants the benefit of natural light without exposure to harmful environmental stressors. The sunshine also translates to savings in your pocket since you won’t have to worry about the electricity bill for all those LED lights.
Climate: In addition to protection from rain and wind, marijuana greenhouses can contain helpful tools like dehumidifiers, fans, air conditioners, and heating systems, none of which are possible for outdoor growers. With the help of these tools, greenhouses can weather all different seasons, making them an excellent choice for year-round cultivation.
What type of greenhouse is best for growing cannabis?
Whether you want to grow recreational weed or medical marijuana, the best greenhouse may be one that you build yourself. If you have the time and skills (or helpers) to construct your own greenhouse, this route will be the most cost-effective.
Building your own greenhouse requires an ideal location facing the sun. A slightly shaded area is fine, but make sure nothing is keeping the sun’s light from reaching your greenhouse. The more hours of direct sunlight, the bigger the yield.
Think about the storage space you’ll need for equipment such as supplemental lighting and nutritional blends. You’ll also need an easily accessible place to store water and soil, so that the greenhouse is a one-stop location for all your cannabis cultivation needs.
Consider which greenhouse material will create the ideal environment for your cannabis. While glass is the traditional material, you can also use fiberglass or plastic. The latter two will be equally effective but not as fragile or expensive. Whichever material you choose, make sure you install proper ventilation to let your plants breathe.
Before you start building a greenhouse, check local laws to see if building permits or other formalities are needed.
Buying a cannabis greenhouse
If DIY is not your style, then you should be able to purchase a top-quality greenhouse at a relatively low cost. Here are two popular design choices:
Polytunnel: These dome-shaped greenhouses have an aluminum base and a covering of polythene. Polytunnels are on the lower end of the price range, starting at around $200. These greenhouses are durable but do need some maintenance, especially replacement of the cover every five years or so.
Cold frames: Cold frames are another affordable choice. While it’s possible to construct a cold frame yourself, you can purchase a solid one for between $300 and $600, depending on the size. Cold frames are constructed out of wood or plastic and covered in clear plastic. This kind of greenhouse can be used as is, with only heat from the sun, especially if you live in a warm, dry climate like California. In a colder climate, consider installing a heating system, also known as a hotbed.
Neither of these choices should break a modest budget, but be prepared to maintain and/or replace parts as necessary.
Growing marijuana in a greenhouse
Once you have selected the type of greenhouse that works best for you, it’s time to put your gardening skills to the test. Here are the most important aspects of growing top-quality weed in a greenhouse.
Soil: First and foremost, invest in top-quality soil as this will impact the entire growing process. Pick a nutrient-packed soil that contains organic substances like compost and worm castings. Pay attention to the pH levels of the soil as well — aim for a range of 5.8 to 6.3. Other qualities to look for in soil include good drainage ability, high oxygen levels, and effective water retention.
Invest in top-quality soil as this will impact the entire growing process. Photo by: Gina Coleman/Weedmaps
Equipment: From heating systems to oscillating fans, the supply list for a cannabis greenhouse can be long. But once you make an initial investment in equipment, most equipment will last season to season.
Knowledge: The most high-tech equipment won’t matter unless you have a thorough foundation in how to grow cannabis . This means understanding when seeds should be sown (generally April), when flowering occurs (8 to 12 weeks typically), and which cannabis strains do best in greenhouses (autoflowering strains such as Purple Punch Auto, Jack Herer , and 8-Ball Kush enjoy a great reputation among cannabis growers).
Should I grow weed in a greenhouse?
To answer this question, consider how much control you would like to have over your crops. If reliable conditions make growing cannabis a more enjoyable experience for you, then a greenhouse may be the way to go. Also, assess how much elbow grease you want to put into the growing process and if you want to build a structure from the ground up. Finally, evaluate your budget and grow goals before you make the decision to grow marijuana in a greenhouse. Whether you choose to grow weed outdoors, indoors, or in a greenhouse, raising plants from seed to harvest can be a rewarding experience.
A primer on growing marijuana in a greenhouse Copy article link to clipboard. Link copied to clipboard. Contents Benefits of growing marijuana in a greenhouse Buying a cannabis