Approaching indoor grow room design with an eye toward efficiency well before the first clone is planted can go a long way to set an operation – and the cultivation team – up for success. In this article, we break down some of the key considerations to keep in mind when designing an efficient indoor grow room.

Location is Everything

Indoor cultivation is a critical aspect of this industry, but finding a location and setting up the best indoor growing setup for weed is about a lot more than locking in prime real estate. A region’s weather and climate conditions impact a facility’s indoor environment and will have a direct influence over whether and to what degree producers incorporate air conditioners, dehumidifiers, and other industrial equipment. Part of choosing a location means figuring out how to keep the outdoor environment from affecting the cultivation team’s ability to keep indoor temperature and humidity in check. Choosing a building that is either outfitted with optimal infrastructure – including power and insulation – or has a substructure that can accommodate future additions that support growers’ ability to control their environment are far better options than having to gut and renovate a building from the ground up to make it operational. Then once the right building is secured, the hard work of indoor grow room design begins.

Before starting build-out, one key factor to consider is how to set up the physical space. Not only does the operation need enough overhead clearance to accommodate equipment like light fixtures and HVAC units, but also plenty of non-cultivation space so that employees can work comfortably and efficiently. Hallways that are wide enough to facilitate the movement of carts and forklifts, storage space that helps the team keep hallways clear, and placing enough space between the benches in each room for employees to easily move around without damaging the plants can go a long way toward keeping workflow running smoothly. Not only that, indoor grow room design is also about the layout of the facility. Ensuring the flow of foot traffic between rooms to keep the team from inadvertently creating biosecurity red flags is another key consideration.

Environmental Design Factors

One of the greatest benefits of indoor cultivation is that growers are better able to maintain control of their environment than they can with an outdoor garden. A huge part of that is making sure the facility has optimal lighting, which typically comes down to choosing between high-pressure sodium (HPS) and LED options.

Considered old-school tech in the world of cannabis cultivation, HPS bulbs hovering in the 600-1000-watt range have been a standard in indoor grow operations for decades – and for good reason. Plants typically perform well under the spectrum offered by HPS lights, and the radiant heat produced by the bulbs helps support overall plant temperature. Plus, growers looking to boost anthocyanin in their plants so they express more purple color tend to find greater success with HPS bulbs over LEDs. However, there are cons to using HPS lights that primarily center around their outdatedness. For one, there’s the risk of fire when HPS bulbs go out. They’re also becoming obsolete which means fewer manufacturers are producing HPS bulbs, making them harder to find and more expensive to buy. While HPS bulbs produce more radiant energy that can benefit the plants, they are less energy-efficient than LEDs and could increase the need for more air conditioning.

LEDs have risen in popularity as a less expensive lighting solution for commercial cultivators, and typically come in 2 configurations: high-bay LEDs and panel LEDs. High-bay LEDs emit high-intensity light and are considered to be a replacement for HPS bulbs. Because the light from high-bay LEDs spreads out more, they’re usually placed farther away from the plants. Panel LEDs on the other hand have lower wattage – 500-700 watts versus the 2000 watts from high bays – so they’re placed much closer to the plants to provide the most even coverage possible. In addition to lower cost, LEDs tend to generate less heat output in the room than HPS. But there’s a flipside: less radiant heat means having to increase dehumidification capacity. 

Cultivators who use high-powered LEDs must create an indoor environment that provides proper airflow and ventilation to nurture the plants’ uptake of light, water, and nutrients. Overcrowding the room with plants can impede these natural processes, as can the space being too small for the amount of heat produced by the industrial equipment in the room – and this has a direct impact on temperature and humidity. Making sure there’s enough air conditioning to manage the heat output from lights, dehumidifiers, fans, and other equipment is another crucial aspect of indoor grow room design. To maintain complete control over their indoor environment, growers need a balanced system with enough capacity to provide plenty of air movement while also mitigating the impact of outside weather and climate conditions. Part of the journey includes resisting the temptation to pack every inch of a room with plants, and instead setting a plant count that helps growers maintain the most control. As a result, some producers may opt for a room design that allows for as much grow space as possible by choosing to incorporate vents and otherwise place HVAC and other equipment outside the room. This has the added benefit of making it much easier to service the equipment away from the plants – reducing the potential for damage. 

Design for Optimal Root Zone Conditions

Setting up optimal substrate conditions is another important factor in designing an efficient grow room. There’s no underestimating the importance of choosing the best size for each indoor grow pot and its benefits not only to the plant but also to the overall production. 

This starts with cultivators first determining how big they want their plants to be. In a small room, for example, double stacking plants is a great way to optimize space, but that requires growing small plants in small pots. The same applies when the cultivation team has to turn over rooms filled with thousands of plants – a process guaranteed to go faster and be less labor intensive when the plants are in 4-inch pots versus 1-gallon pots.  Substrate media is another consideration, as deciding between coco coir and Rockwool includes determining which will achieve the drybacks that will steer the crops toward desired outcomes. 

From whether to hand-fill and reuse pots, to opting for slabs over pots, to watering by hand versus auto-irrigation, every decision about the grow room setup has a direct impact on time, labor, and ultimately profitability.

In Summary:

• Before designing grow rooms, cultivators must consider the impact that outside climate conditions and building infrastructure will have on their production.
• For optimal efficiency, each room design must factor in overhead clearance, allow for storage, and facilitate employee workflow.
• Lighting choice (HPS vs LEDs), how they’re configured, as well as room size and plant density all factor into how producers design a balanced system for managing airflow, temperature, and humidity in their environment.
• Pot size, substrate choice, and the processes used to manage root zone conditions directly impact time, labor, and ultimately profitability.