Indoor Cannabis Growing

Getting Started With Indoor Cannabis Growing

Prohibition was motivation enough for tenacious growers to pivot and move their outdoor cultivations to indoor spaces. These days, large-scale indoor and greenhouse facilities are essential to the multi-billion dollar cannabis industry.

Home growers and entrepreneurs exploring how to grow weed indoors for the first time learn quickly that it takes more than a few seeds, a big room, and a couple of lights to get started. In this article, we discuss key things cultivators should know before getting started with indoor cannabis growing.

The benefits of growing indoors

While prohibition may have been the initial inspiration for growers to move their gardens indoors, satisfying the demands of an expanding consumer and patient base has reinforced an ongoing need for indoor and greenhouse setups. Since cannabis is an annual dioecious flowering plant, indoor and greenhouse operations allow growers to cultivate multiple harvests per year. And since the industry centers around a federal Schedule 1 substance that must adhere to zoning and other local ordinances, indoor operations provide a level of privacy and security that outdoor gardens may not. But the benefits of indoor cultivation don’t stop there.

Cannabis is different from a lot of industrial crops in that it doesn’t require thousands of acres to produce enough biomass to fulfill demand. Whether growing in a hallway closet at home or a hundred-thousand-square-foot commercial facility, cultivators can achieve high yields in indoor spaces of all shapes and sizes. This in itself sets the stage for one of the major benefits of indoor cultivation: growers having complete control of their environment. The great outdoors has everything plants need to survive, but the environmental conditions vary constantly. Air quality, inclement weather, and pests/plant diseases from nearby crops are just a few of the elements that can impact outdoor grows. Indoor and greenhouse operations put cultivators in the role of Mother Nature, allowing them greater control over the variabilities in their environment. And when applied successfully, this level of control helps set a framework for consistent, repeatable quality with every harvest.

Start with clear objectives

Setting up an indoor grow takes more than seeds or clones, a couple of lights, some fans, and a watering can. Factors like licensing, equipment, labor, construction, electricity, and water use – things that take planning, logistics, and money to set up – can also come into play. The best indoor grow setup for weed should set the cultivator up for success by nurturing each plant’s ability to grow to its fullest potential. So before building out a grow space or facility, having clear objectives for what you hope to achieve with the cultivation will help inform every decision you make. Some examples...

  • Are you a home grower cultivating for personal use, or a licensed professional starting a brand?
  • How much grow space are you working with: A closet? Basement? A 50,000-square-foot facility?
  • How many plants are you cultivating: A few? Couple hundred? Thousands?
  • What’s the end product: Top-shelf flower? White label products? Concentrates? Something else?

Answering these and other questions upfront can provide a lot of information that will ultimately guide every facet of the cultivation – from budget and equipment to labor and processing, and more – and enable growers to tailor the rooms based on their objectives. 

Indoor cultivation design and engineering considerations

To create optimal indoor or greenhouse environments for their plants, cultivators must constantly manage light, water, temperature, CO2, and humidity in ways that align with their objectives – and that can involve making trade-offs. Let’s say you own a hundred thousand-square-foot facility in a market that limits the number of plants you can legally grow under a cultivation license. Rather than putting time, effort, and funding into converting the entire building into a commercial facility, it may be more practical to build out 5,000 square feet of space to start and then scale up over time. Indoor cultivation design and engineering is more about leveraging every square foot of licensed canopy that’s available than it is about blowing the budget to go big. 

Active grow rooms don’t just contain row after row of plants. Industrial lighting and other equipment like air conditioning units and dehumidifiers are crucial for maintaining an optimal environment, and therefore must also be factored into each room’s design. Here are some considerations to keep in mind:

  • Irrigation: Water is essential to the survival of all plants. When setting up an indoor cannabis grow, cultivators have to figure out the best way to ensure consistent, precision irrigation for each of their plants or they risk losing their crops. If they’re hand watering to start, cultivators looking to scale may need to reevaluate and adjust based on their objectives. So instead of increasingly setting aside hours for one person to drag a hose around watering every plant, investing in a reliable pressure-compensating drip irrigation system may be a more reliable, less labor-intensive option in the long run.


  • Lighting: When harnessing the power of the sun isn’t an option, cultivators rely on artificial lighting to get the job done. Photosynthetic photon flux density (PPFD), which defines the amount of photosynthetically active photos that reach the plant every second, can go a long way to help growers determine the amount of light their canopy needs. Light intensity has a direct relationship to the plant’s ability to uptake CO2 – that’s why when it comes to making lighting decisions, PPFD is a better reference point than luxe or lumens. And because proper height and spacing help prevent hot and dim spots throughout the canopy, lighting density is another key factor to consider when building out an indoor grow.


  • Temperature & Humidity: Once a room is packed with plants, the necessary equipment, and the occasional human, managing temperature and humidity levels can be a challenge. Indoor environments need enough CO2 to support the crops, but combining too much humidity with high temperatures can lead to mold and a host of other issues. Dehumidifiers and air conditioners help growers maintain optimal temperature and humidity levels at every stage of growth. And when it comes to choosing the right environmental equipment, make/model is just one factor; the units must also be sized properly for each room/grow space.


  • Ventilation & Airflow: Part of managing temperature and humidity – and overall plant health – is ensuring proper airflow and ventilation. Overcrowding a room not only means each plant has to work much harder to take in water, light, and nutrients; but it can also facilitate the spread of pathogens like powdery mildew. The right filter will help ensure clean ventilation when pulling air indoors from the outside, and good quality fans will keep the air moving. Growers should also consider how room/space size, the number of BTUs of heat produced by the industrial equipment sharing space with the plants, and local smell ordinances may impact ventilation.

In Summary:

  • Not only can cultivators achieve high yields in indoor spaces of all shapes and sizes, but indoor and greenhouse grows offers cultivators much greater control over their environment.
  • Establishing clear objectives will go a long way to inform every decision made when setting up an indoor cultivation.
  • How growers approach their irrigation, lighting, temperature/humidity, and ventilation/airflow comes down to one key consideration: being able to leverage every square foot of licensed canopy that’s available.

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