The lines between food growing methods and cannabis are slowly starting to blur. Growers of leafy greens and lettuce in controlled environments have long used multilevel grow spaces. Now this trend is also developing in cannabis cultivation.
In a never-ending quest to improve efficiency and increase yields, multi-level growing environments have the obvious advantage of allowing more production and higher yields in the same square meters. However, there are also some drawbacks. Before constructing a facility, carefully consider the benefits and risks of multilevel cultivation.
In comparison, greens are relatively short plants. They have limited height requirements, allowing you to accommodate multiple tiers even with a relatively low overall height. Once planted, most Greenleaf strains require very little hands-on intervention other than regular checks and their automatic watering system.
In contrast, mature cannabis plants are typically three to six times taller than ready-to-harvest greens, depending on the time spent on the greens and the method of cultivation. Cannabis plants also require hands-on intervention often associated with trellis and pruning. This means you need to consider the availability of higher tiers so as not to compromise operational efficiency.
These two factors make layer gardening easier and more feasible for wide application in green vegetable production than cannabis production. However, this doesn't mean that it shouldn't be considered under certain circumstances.
Lighting requirements and vertical space
Lighting technology and choices have a direct impact on ceiling heights and upper floor access requirements of a multilevel facility. Depending on the level of lighting desired and the specific fixtures used, this can mean adding significant vertical space to a stacked extension.
For example, HID lamps usually require at least 24 inches, more commonly 48 inches, and sometimes as much as 72 inches from the top of the shade to the bottom of the lamp.
On the other hand, you can usually mount the LED light closer to the screen - in some cases just a few centimeters. This is because most LED lamps produce more collimated light and radiate less heat than HID lamps.
When using LED, double stack grow rooms require less vertical space than HID lighting. In addition, access to the upper levels is much more convenient.
Multi-stage irrigation design: an uphill battle
Irrigation design is another variable to consider when planning a multilevel facility. Pump performance decreases with increasing vertical flow requirements (buoyancy), so this must be taken into account when planning irrigation.
Access to sprinklers and drip heads for maintenance is also important. Let's say you need access to every plant in the room on a certain day of the grow cycle to ensure you can properly care for not only the plants but all the components of the watering and pergola.
When does multi-stage cultivation make sense?
Keep in mind that when building a growing facility, the real estate itself (sqm) accounts for only a small part of the overall construction budget in most cases. Equipping the space with infrastructure suitable for cultivation accounts for a large part of the costs. Therefore, growing multiple tiers is rarely a more budget-friendly option than growing one tiers. Although very high square footage is sometimes an exception. In today's industrial environment, we mostly see growers who choose to grow at multiple levels, doing so in a grow room. Here they are more comfortable with low-power lighting technology, and the plants are shorter and still don't need trellises. This provides a happy centerpiece where they can enhance the overall flower canopy within a given space while limiting the challenges that come with layered fixtures.
Despite the challenges of growing indoors in a multi-level environment, even with flowers, if every element is considered and cared for at a design level, it can be a good choice.