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growing weed in a polytunnel

Many folks in northern latitudes start their seeds indoors in April under grow lights and transfer them to a greenhouse in May. Your own schedule will depend on your climate and growing season, of course.

To help you get on your way, DripWorks is happy to provide you some basic tips on how to grow marijuana in a greenhouse or high tunnel.

Generally, two basic options are available for growing your pot plants. You can grow each marijuana plant separately in its own container, or you can put the plants in the ground. Using containers will make the plants easier to work with and to move if you want to transplant them.

Once you have purchased or built your greenhouse or high tunnel, you’ll need to decide where to put it. Generally, a spot with southern exposure is best. This will provide a steady source of growth-inducing sunlight to your plants. You may also want to locate your high tunnel or greenhouse in an inconspicuous spot to deter thieves, vandals and other troublemakers.

Growing Marijuana in a High Tunnel or Greenhouse

If you live in a climate prone to more clouds than sun, you may want to consider investing in auto-flowering seeds. These will flower in a set time rather than depending on sunlight to spark flowering.

Of course, that means high tunnels cost significantly less than greenhouses. How much less depends on the options you are looking for. A variety of high tunnel greenhouse kits and traditional greenhouse kits are available for purchase. If you are handy and looking to save, you can also assemble your own high tunnel or greenhouse with some basic materials.

You will want to be sure to give your cannabis plants adequate amounts of water and fertilizer to ensure steady, strong growth throughout the season. A drip irrigation system can supply these essentials reliably and economically. DripWorks.com has an entire section on the best irrigation products to grow cannabis.

Greenhouse vs. High Tunnel

First, let’s get some terminology issues out of the way. Greenhouses and high tunnels are similar but not exactly the same.

You can start with marijuana seeds or clones. Whichever you choose, pick the highest-quality stock you can find. This is no place to pinch pennies. Dealing with a reputable company and getting top-notch genetics will help ensure a bountiful crop that’s high in quality as well as quantity.

Growing weed in a polytunnel

The more professional greenhouse grower will take care to introduce new, good quality soil/fertilizer each year and keep the greenhouse clean and tidy to minimise potential for pests and disease. Some greenhouse growers use strategically placed fencing and shrubs to make the greenhouse inaccessible to unwanted visitors and invisible to prying eyes. Greenhouses are cheap to buy. You can buy small low cost plastic ones for not much more than a hundred euros. Even cheaper ones are available with plastic covers. They are available everywhere and come in any shape/size required for all budgets. Some of the modern polycarbonate greenhouses are also opaque giving instant privacy and have lockable doors. What more could you need in your back garden? Remember that poor quality cannabis seeds can’t produce connoisseur quality cannabis, no matter how well you grow them. Invest in the best cannabis seeds you can get from a company with a proven reputation, and enjoying growing your own cannabis in a greenhouse.

Greenhouse growers are split into two main groups; 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. That could be a problem if you are away and unable to visit your plants.

Feminized seed varieties grow very well in greenhouses. Often, they will grow vegatively until they sense the shortening days, and will start to show first signs of bloom around August, depending on your variety. In the northern hemisphere feminized seeds are often grown from around April to October in a greenhouse.

With a little bit of thought and planning, growing cannabis seeds in a greenhouse can be a safe, secure and pleasurable way for the home-grower to be self sufficient in recreational or medical cannabis. Greenhouse-grown cannabis is incredibly potent when grown from good cannabis seeds. It’s no surprise that more people than ever are growing in greenhouses and enjoying the benefits.

Greenhouse options for cannabis growers

When growing with good cannabis seeds in a greenhouse remember that some plants will grow as wide as they are tall especially if they have plenty of sun, good soil and ample root space. Remember too that a few seeds could provide a years worth of medication or recreational weed, so regard the cannabis seed as an investment and get a good variety. Cannabis seeds are one area of your life where you really don’t need to compromise. Look at the Dutch Passion website for some cannabis cup winning options. Proven varieties for greenhouse growing, especially at northern latitudes, includes Shaman, Durban Poison, Passion #1, Frisian Dew and Frisian Duck. These varieties have been used by numerous repeat growers over many years. They have passed stringent standards for potency, quality, pest/mold resistance and vigour. Growing these feminized seeds in a greenhouse will deliver excellent results.

As previously mentioned, some greenhouses have windows that can be opened to let any monster plants grow out. But a safer option is to use cord to try to ‘tie down’ the plants if they do start growing massively. The photos above show what can happen when a prolific strain starts to turn into a large bush that wants to grow as high as a small tree. The plant simply becomes too tall for the greenhouse. The soil conditions, temperatures and good care resulted in a plant that was thriving as if in the jungle rather than a garden in northern Europe.

Some growers equip their greenhouses with a ‘darkening’ system. Essentially this involves using dark blinds/curtains to create blackout conditions inside even when it is sunny outside. This can be used to simulate short summer days and ‘force’ the plants to start flowering and producing buds much sooner than normal. Although this involves extra expense it is one way of accelerating greenhouse weed production. The grower simply uses the blinds to reduce daily light exposure to 12 hours (or less) and the plants in the greenhouse respond by flowering.

Greenhouse cultivation of cannabis seeds. Using pots vs planting directly into the ground

Many greenhouse growers also arrange a hosepipe/water connection near their greenhouse. This simplifies the process of getting water to your plants. The last thing you need on a hot day is numerous long walks from your house to the greenhouse with a watering can.

Anyone that has been in a greenhouse on an early spring day will note how quickly they warm up in sunshine. This allows growers to get their preferred cannabis seed varieties started earlier in the season than they could outdoors. This allows the growing season in a greenhouse to start earlier. Your greenhouse will therefore benefit from larger plants and subsequently superior harvests. Cold nights can be mitigated with the use of greenhouse heaters that are available to purchase at any garden centre.