Last time we began a discussion on how to conserve resources in an indoor grow. We focused primarily on lighting technology, namely LEDs and LECs.

Today we’ll continue by focusing on legal and regulatory changes, water conservation and some organizations that can help growers save power.

Legal and Regulatory Changes

Sometimes power savings can result from a legal or regulatory change. For example, because of legalization, many growers have moved from basements and other residential environment to commercial settings like warehouses. This opens up the ability to use advances like three phase power to make a grow more efficient.

Many jurisdictions limit the size of a grow based on plant count. While this type of system can be convenient for regulators and lawmakers, most growers know that it makes no sense.

That’s because the main limiting factors of indoor cannabis cultivation are light and space, not plant counts. If you give me a 1,000 watt HPS and a 4’ x 4’ space, I can produce a nearly identical amount of cannabis using one huge plant or 100 smaller ones.

Limiting grows based on plant count incentivizes larger plants. After all, if you tell me I’m allowed to flower six plants at a time, I can produce more cannabis with six giant plants than I can with six tiny ones. But growing larger plants requires longer veg time. It can take up to 90 days to veg if you are growing one plant per light, as opposed to seven days of veg to grow 100 small plants to flowering size under that same light.

Fortunately, many jurisdictions have begun to limit the size of cultivation operations based on square feet of flowering canopy. Growers are given a set amount of space for flowering, but remain free to use as many (or as few) plants as they choose. By using more small plants (as opposed to fewer larger ones), growers can gain energy efficiency while reducing production costs without compromising either quality or yield.

Water

Up to this point we have been focusing on power, but electricity is not the only limited resource that cannabis plants consume. All plants need water, and cannabis is no exception.

I want to stop for a minute to dispel a myth about cannabis—namely that it uses significantly more water than other crops. This is simply not true. In fact, cannabis is among the more efficient crops with regard to intensity of water usage.

Water usage for crops is often measure in acre feet, which is defined as the amount of water required to cover one acre of land with one foot of water. According to the Washington Post, cannabis requires about 1.4 acre feet per acre of crop. That’s more than crops like grapes, melons and cucumbers, but significantly less than a number of other crops, including almonds, pistachios, corn, potatoes, alfalfa and tree fruit (just to name a few).

In addition to looking at straight water consumption per acre, we can look at the water consumption per acre relative to the economic value of what is produced on that acre. Because an acre of cannabis can produce thousands of times more value (measured in dollars) than the other crops, measuring the amount of water used per dollar of value produced makes cannabis one of the most efficient plants on the planet.

Of course, we still need to do everything we can as cannabis cultivators to conserve as much water as possible. Both indoor and outdoor growers can build rainwater catchment systems that will allow the grower to collect and reuse rainwater.

Indoors, we can recapture a great deal of the water that evaporates off plants when it becomes condensate in the HVAC system. That water is not only free but completely clean and can be reused without filtration.

Speaking of filtration, indoor growers should also be thinking about filtering the runoff from plants, whether they are reusing it or not. Of course filtering and reusing water is ideal, but I haven’t seen any cost-effective filtration systems that can clean water adequately for reuse.

Even if you aren’t reusing your water, you should filter it before disposing of it. Otherwise the accumulated mineral salts in the water will affect local groundwater and watersheds.

Third Party Assistance

One of the great benefits of the movement toward legalization is that cannabis growers no longer operate underground (literally or figuratively). Rather than hiding from utilities, we can engage with them in an effort to operate more efficiently.

In Oregon, both Pacific Power and PG & E (the two largest electric utilities) have begun outreach programs to help growers find solutions that use as little power as possible.

Third party organizations exist to help with this issue as well. The Energy Trust of Oregon is an independent nonprofit organization dedicated to providing utility customers with low-cost, clean energy solutions. They are eager to work with the cannabis industry to help us to become more efficient.

A new non-profit called the Resource Innovation Institute has recently formed as well. Based in Portland, Oregon, their mission is to provide certification standards, technology reviews and a platform for best practices on resource conservation specifically for the cannabis industry.

You can contact one of these organizations for guidance and assistance or look for a similar organization in your area.

Indoor cannabis cultivation will continue as long as substantial demand exists. With new markets continuing to open up and demand steadily rising, it’s safe to say that we will see an explosion of indoor cannabis cultivation in the coming years.

Over time, we will see a transition to more sun grown cannabis. But in the meantime, we have a responsibility to take whatever steps we can to reduce our environmental impact.