Growing cannabis in a greenhouse is getting increasingly popular, especially among more experienced growers. Still, any technique comes with a few tricks of the trade you need to know first – and we’re happy to help out with that. Any growers thinking about using a greenhouse for cannabis need to read this blog before they decide!
Why Grow Cannabis In A Greenhouse?
Combining first-class genetics with optimal grow conditions is the surest way to achieve a full harvest of prime buds. It can help colas grow bigger and ensure greater impact of beefed up cannabinoid content. Below, we’ll explain why a greenhouse promotes optimal conditions for (semi) outdoor cannabis growing.
Out in the garden or on a balcony, cannabis plants get subjected to considerable temperature fluctuations. Particularly in Northern countries such as the Netherlands, you can never be quite sure how wet the summer will turn out. Rain can be a real crop killer, as it can promote growth of fungi such as bud rot. Growers often fail to notice such threats until after they collect the harvest, and by then it is too late to avoid serious disappointment.
A greenhouse shelters your plants from the rain. If you wish, you can add heating, fans, or even air conditioning. Another option is to just open all the glass window panes and let in some fresh air for circulation. And if your plants needs some extra light due to a cloudy late spring, you can always add lighting rigs to brighten up that greenhouse cannabis grow.
Cheaper Than Indoor Growing
This may sound odd, but investing in a greenhouse can be a way for cannabis growers to save money. It’s a bit like installing solar panels: it’s an investment initially, but it’s going to cut your power expenses from day one. There’s lots of optional elements to add if you wish, but these are only necessary in extreme weather conditions. Normally speaking, simply opening or closing a few windows will do the trick. That means a cannabis greenhouse will pay its own way in a few years of use; plus you’ll be saving space indoors as a bonus.
Controlling The Cannabis Grow Cycle In A Greenhouse
The life cycle of cannabis plants is dictated by the amount of life they receive. Out in the open, they will start flowering once the days start to grow shorter. By the end of the flowering stage, the buds reach full potential, signalling harvest time. Advanced greenhouses feature lighting rigs to boost the amount of light received, or options for darkening the room. This allows for all-season growing, without having to rely on seasonal changes in daylight hours.
Extending The Flowering Phase
Since buds are formed in the final flowering phase, many growers aim to extend this stage to maximum effect. This is hard to achieve when growing outdoors, but having a greenhouse makes it a whole lot easier. Cold, sunny autumn days can foster very agreeable greenhouse temperatures for cannabis crops. Adding some extra light at the start or the end of the day will trick the plants into thinking the days are not getting shorter yet. Even extending the flowering stage by just two weeks will likely show in the harvest that follows.
Greenhouse Cannabis Protection
A greenhouse can protect a cannabis grow from just about any external threat. As experienced outdoor growers will admit, the weather can be a plant’s worst enemy. Pests such as slugs and aphids prey on cannabis plants, and even some of the bigger predators can fancy a bite of ganja every now and then. In rural areas, rabbits can pose a real threat to fresh cannabis leaves. What’s more, anyone looking for some added privacy can opt for tinted glass greenhouses to keep their cannabis projects hidden from inquisitive neighbours. In short, a greenhouse can help keep all kinds of unwanted guests away from your grow.
Two Types Of Greenhouse Cannabis Grows
Growing cannabis in a greenhouse can be done in two ways. Some prefer to keep their plants in pots, while other growers are convinced that cannabis grows best in open soil, even in a greenhouse. Fortunately, either approach can be equally successful.
Pots In Greenhouses
Obviously, plants in pots are easier to move around than open soil plants. This can come in handy either when growers want to be discreet about their plants with respect to visitors, or when mildew or similar problems emerge that call for removal of one or more plants. The downside of growing in pots is the increased need for adding nutrients that would normally be available directly from the soil. This can turn into an advantage, however, because it allows growers complete control over any nutrients they add. In addition, cannabis plants in pots need water every day in warm weather. For growers who have to be away from home, this can be a real issue if they decide to grow in pots.
Growing Greenhouse Cannabis In Soil
Planting cannabis in open soil comes with a certain degree of freedom for growers. Luckily, a greenhouse offers great opportunities for doing just that with the right preparations in place. As long as plants are firmly rooted in open soil, their root systems can grow larger and stronger than any potted plant’s could. It allows them to absorb water more easily, which could theoretically allow growers to be away for up to two weeks without finding someone to look after the plants. It is critical, however, to make sure the ground supports rich and natural soil life. That calls for annual refreshment, preferably using a mixture of soil, compost and (organic) fertilizer to ensure sufficient nutrients are present. Another great idea for greenhouse grows: give your cannabis plants some friendly neighbours by clever use of companion planting!
Growing in open soil is all but synonymous for giant-size plants. Sometimes, greenhouse cannabis growers have to remove the roofing panels to make room for their crops. Of course, these are extreme examples; a bit of wire is usually enough to make plants grow laterally instead of upwards. Low Stress Training (LST), Screen Of Green (SCRoG), or Mainlining techniques are well-suited for growth control. Of course, the obvious disadvantage of growing in open soil is the difficulty of relocating plants once they’re firmly rooted inside the greenhouse.
A Greenhouse Just In Case
Another option is to use a greenhouse only if the weather threatens to make a turn for the worse. As long as you save some space for your ganja grow, you can just leave them out in the open air in their pots. That way, you can profit from fresh air, sunshine, and rainfall to maximum effect, while still being able to bring the whole grow inside if you see a storm, shower, or heatwave approaching. You can also choose to leave your cannabis grow outside the greenhouse until the flowering stage is almost complete. This will help shield the harvest from late-summer fog and dew to prevent mould from catching on.
An added benefit of having a greenhouse in the garden is the ability to keep your (potted) plants safe all year round, while having the perfect grow spot ready and waiting for the cannabis season to begin!
Cannabis Greenhouse Decisions
Greenhouses come in all shapes ad sizes, often with price tags to match. Still, prices are usually pretty good indicators of quality, so if you want to save money, try to cut back on other expenses. Cheap greenhouses tend to be poorly isolated, ramshackle affairs that can even get blown over if a storm hits. That would be a real waste of money, time, and hard work.
Think about the size that fits your garden, and be sure to consult your significant other before you proceed. Consider the appropriate height for the roof and drainpipes, especially if you or your intended plants are tall. You can also opt for a partially subterranean greenhouse to literally keep a low profile, or work with fixed flooring or grow containers as your bottom surface if you like.
If you have the chance, we suggest trying a conservatory-model greenhouse that uses the side of your house as its rear wall. This is a clever way of heating the greenhouse automatically, using warmth generated indoors by transferring it through your outer wall. Depending on which direction the glass panels face, a south or west-facing brick wall also traps heat from the afternoon sun, which is then gradually released over the course of the cooler evening hours. The added support from the brick or concrete wall reduces the risk of storm calamities.
Free-standing greenhouses come in high-quality materials too, and of course, these offer the advantage of being fit for any garden grow spot. They are usually easy to build and disassemble. When buying a greenhouse, make sure that the frame (usually made of wood or aluminium) is not too bulky. After all, a bulky frame will block more sunlight than a slender one.
Cannabis Seeds: The Best Greenhouse Grows
Once you decide to go for greenhouse grows, your options for picking cannabis seeds are bound expand considerably. Obviously, it all gets better if you order the finest genetics available online, but Amsterdam Genetics has you covered when it comes to that.
You may find that even strains you’d normally consider out of your league suddenly become an option. How about a speedy autoflower, allowing you to consider two consecutive grows in one outdoor season? Great idea! In fact, having a greenhouse could even allow you to grow cannabis outdoor in winter if you do it right. Or perhaps it’s time to try that haze sativa grow you’ve been secretly dreaming of? Or a nice and compact bush of kush? The choice is yours, of course, but once that greenhouse is up and running, you’d better make sure you have the perfect cannabis seeds ready and waiting!