Growing for All Seasons in a Greenhouse

Cultivating cannabis year-round in a greenhouse sounds easy. After all, it’s a protective barrier so you’re not bound by the restrictions nature sets out, but the idea that this kind of farming means no setbacks based on the season is merely a common misconception. In this article, we’re going to explore some of the many seasonal differences greenhouse producers will experience, from downtime during harvest, crop flipping strategies, and the many challenges brought on by extreme summer temperatures.

Downtime for harvest

Contrary to popular belief, greenhouse growth is not something that can happen 365 days a year, and that is especially true when it comes time to harvest, as producers must shut down production and complete sterilization of the facility. It can take anywhere from days to weeks to harvest, clean a greenhouse, and set up a new crop. Though it might seem like it’d be easy enough to keep a constant rotation, with half of the crop ready to pick while the rest continues to flourish, quality regulations and standards make that impossible.

Cross-pollination is a valid concern, as is how difficult it would be to do a deep clean of the greenhouse with half of it still stocked with growing plants. To avoid those problems, cultivators must go the extra mile and close down production during this time.

Some large-scale greenhouse cultivators, like Greenway Greenhouse (CSE: GWAY) limit downtime for harvest by segmenting their cultivation, processing and vegetation cycles. Teenage plants are brought in from their Nursery down the road, as soon as the last lot are harvested and the facility cleaned.

Crop flipping

If you’re an avid gardener then you might have heard the term flipping, which refers to the process of going from a light cycle suitable for the vegetative stage to one that is required to push cannabis plants into the next phase of life and so they may absorb the most light and nutrients during the vegetative stage. This is something that happens naturally outdoors in the warmer months, but greenhouses that function all year long must put a lot more work into making this shift happen.

Lights must often be installed to compensate for shorter days, heating becomes a necessity as the temperatures drop, especially at night, and in some cases, if the crop rotation isn’t timed precisely, it might also mean installing fixtures or covers that can black out the natural light.

Venting

Venting greenhouses is a necessary step that brings on added expense to this endeavour, both in terms of setup and keeping them running (power), and it’s absolutely necessary for the summer months when condensation builds, which can lead to devastating mould growth that could destroy an entire crop, and in the winter, these systems must be built to buffer the cold. Fresh air is essential, but too much cold at once can shock cannabis plants, so this isn’t as easy as installing a few open vents.

In the summertime, the warm air is largely welcomed. However, producers that wish to grow cannabis all year round must make adjustments to accommodate for the lower temperatures outside – a task that never truly ends no matter the season.

For a greenhouse that exceeds 10 000 sq ft, this venting process is often automated using sophisticated sensors and software.

Summertime blues

Now you might be thinking that this struggle is mainly only a winter problem, leaving growers to enjoy the glorious power of warmth and sunshine in the summer months, but the warmer weather brings its own challenges. Higher temperatures mean more condensation and of course heat – two things that when combined increase the chances of mould growth, but that’s not all. It also means longer days and shorter nights, which may or may not line up with growing cycles. Then there are the pests and transmittable diseases, many of which are plentiful outdoors in summer, making it easier for an infestation to take hold, and choke a whole crop.

With giant windows looming on all sides, enhancing the sun's natural UV rays too much could be just as devastating even inside a greenhouse, burning leaves, drying up much-needed moisture in the soil, and raising temperatures inside so high that it can be dangerous for workers to spend too long inside.

Expense

Growing year-round in a greenhouse does increase output, but it’s also important to note that this extra bounty doesn’t come cheap. Building a structure that will keep heat in, vent, and supplement light as needed is far more expensive than putting up a greenhouse that will only be used for the summer months. Cutting corners on the cost of building materials might save a few dollars in the beginning, but when the whole thing needs to be replaced in a few years, the difference will quickly become obvious. Then producers must consider the structures within the space, dishing out extra for treated wood metal, plastic or glass shelving, and storage spaces to avoid rot.

There are many benefits to growing in a greenhouse. Still, those that take on this challenge have quite a task on their hands, and it’s one that’s nowhere as easy as most consumers believe.