Troubleshooting common issues with indoor cannabis plants

Approaching the grow holistically

Anyone cultivating in an indoor environment packed with plants, people, and heavy industrial equipment is bound to face some challenges. But a grow cycle only lasts for so long, and when cultivators regularly have to shift their focus away from nurturing plant development to address issues that arise, that can negatively impact the business in the long run.

When cultivating indoor flower, weed and its requirements for proper airflow, lighting, and irrigation will change with each growth cycle, and growers must always be able to support their plants’ ability to transpire, photosynthesize, and take in nutrients along the way. Establishing optimal root zone and environmental conditions right at the beginning sets the parameters crop-steering cultivators need as a jumping-off point for tracking and monitoring their plants. This represents a more holistic approach to cultivation that makes managing many of the issues that inevitably come up much easier.

A huge part of this is making sure plants have what they need whether a human is present or not, especially at night. When the overnight strategy is to go lights off and drop the temperature, an improperly set HVAC system could cause humidity levels to spike so high that plants can’t transpire, inhibiting their ability to take in nutrients. This results in smaller drybacks, which ultimately leads to smaller plants and low yields. But rather than approaching nighttime differentials as a game of trial and error, growers that take the time to understand the relationship between temperature, humidity, and VPD are better able to make more informed decisions about how to set up their HVAC and other systems so plants may continue to thrive even after everyone has gone home for the day.

With genetics appearing more at the forefront – and consumer expectations higher than ever – being able to support indoor bud development and maintenance at every phase of growth is crucial. And considering each cultivar has its own path of progression – one strain might start forming buds at day 14, whereas another won’t show them until day 24 –  the real challenge is figuring out how to incorporate solutions that benefit the entire garden. When there’s too much humidity in the environment or the irrigation strategy isn’t right for example, plants can grow smaller buds which results in lower yields. But when a grow cycle only lasts for so long, it’s important to choose cultivars whose genetic potential can be achieved within that period. If the production timeline is 55 days but one individual strain in the garden takes 65 days to yield, it may be time to assess whether there’s enough return in putting in that extra 10 days of work.

Then once harvest is over, the last phase of due diligence begins. If 10-14 days for drying and roughly 3 weeks for curing is the sweet spot, then the production schedule must accommodate this timeline. Rushing the drying and curing process could cause buds to become crusty on the outside while retaining too much moisture on the inside, resulting in a less-than-favorable consumer experience. After the cultivation team has put tons of effort into growing crowd-pleasing flower, using water activity meter to track and monitor moisture data reveals far more than a snap test ever could – and creates a reliable, repeatable process that will benefit the business in the long run.

Prevention as the cure

All commercial growers can look forward to eventually dealing with pests and pathogens – especially powdery mildew, which if left unchecked can spread easily in indoor and greenhouse environments. While applying fungicides is certainly an effective way to treat powdery mildew, it doesn’t address the root cause of the infection, which all but guarantees its inevitable return. Figuring out how to prevent and treat powdery mildew in indoor cannabis plants using a broader integrated pest management (IPM) approach can be a far more effective strategy than tackling each outbreak as it comes.

Incorporating a good air filtration system for proper ventilation, adding supplemental CO2, and using air conditioning to manage temperature fluctuations help create environmental conditions that support plants while being unfriendly to powdery mildew. Choosing cultivars that are resistant to powdery mildew is another approach. But at the end of the day, adopting good biosecurity practices – from disinfecting seeds and new equipment and regularly cleaning trimmers and other tools, to wearing hair nets and following decontamination protocols when moving from room to room – helps reduce the likelihood of an outbreak while also minimizing the pathogen’s spread in the event of one.

Key takeaways

• Rather than constantly chasing issues, a holistic approach to managing their garden makes dealing with common cultivation issues much easier.
• Understanding the relationship between temperature, humidity, and VPD goes a long way toward informing growers’ decisions about optimal environment and root zone conditions, day and night.
• Each cultivar has its own path to progress, making it crucial that growers assess the viability of each strain in their grow.
• The drying and curing process needs as much due diligence as the rest of the grow cycle.
• Biosecurity practices and staying on top of sanitation are crucial for mitigating harmful pests and pathogens.

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