When problems arise in hydroponic cannabis operations, it’s important to act quickly. Unfortunately, diagnosis isn’t always straightforward. For example, wilting can result from either drought or overwatering, or chlorosis may stem from iron deficiency or excess phosphorus. Identifying the source requires a systematic process of elimination.
In this blog post, we’ll cover six common areas where problems often occur, along with preventive measures growers can take to keep their operations running smoothly.
Issue 1: Environment
Cannabis is highly sensitive to its environment, and several environmental factors must be carefully controlled to grow healthy, productive plants. The following are especially critical:
Lighting
Light affects not only the plant, but also the surrounding environment, affecting temperature, transpiration and vapor pressure deficit (VPD). It must be properly managed. If plants are getting burned, the light is too intense, so the lighting source may need to be changed or the fixture adjusted. If overhead lighting isn’t reaching the lower canopy, consider adding canopy lighting. The light intensity and spectrum should match the plant’s growth stage.
Temperature and humidity
Research shows the ideal daytime temperature for cannabis is 25–30°C (77–86°F),[1] dropping to around 21°C (70°F) at night.[2] Optimal relative humidity depends on the plant’s growth stage and target VPD. For example, juvenile plants require a VPD of 0.8 kPa, which equates to 75% relative humidity at 25°C (77°F) or 80% at 30°C (86°F).
If the temperature or humidity is off, start by checking the thermostat and confirming it’s properly calibrated. If it’s accurate and functioning, the issue may lie with the HVAC system. Signs of HVAC trouble include excessive heat or cold, condensation on walls and dry air that causes throat irritation. Always follow the HVAC manufacturer’s guidelines for regular maintenance and servicing.
Water
Even if your water source was vetted before use, it requires consistent monitoring to ensure it remains clean and suitable for hydroponics. Check the dissolved oxygen levels regularly and keep the water temperature between 65°F and 75°F to support proper oxygenation.
Irrigation frequency and volume are also important—both overwatering and underwatering can harm plant health.
Hydroponic systems are prone to biofilms and clogs, which may lead to nutrient deficiencies, drought stress or more pests and pathogens. Inspect for clogs and clean the irrigation system as needed.
Issue 2: Nutrient management
Without the right nutrients at the right times, plants can’t grow at their best. Deficiencies or imbalances make them susceptible to pests and diseases, reduced bud quality and lower yields. To rule out nutrient issues, check the following:
- Balanced formula: Make sure the nutrient solution provides the right nutrients in the correct ratios for the plant’s growth stage. If you’re mixing your own, double-check both the nutrient ratios and how you’ve prepared the stock tank solution. Improper mixing or incompatible nutrient interactions can throw off the ion balance, causing nutrient toxicities or deficiencies. Regular tissue sampling is a reliable method of confirming proper nutrient uptake and balance.
- EC and pH: Measure the EC to verify plants are getting the right nutrient strength without overfertilization. Monitor the pH of the solution and substrate; nutrient availability is optimal when pH is between 5.8 and 6.3.
- Nutrient source: Fertilizer selection matters. Choose products that are compatible with hydroponic systems. Some fertilizers contain salts or compounds that aren’t well-suited to recirculating setups, and some may include heavy metals. The American Association of Plant Food Control Officials (AAPFCO) provides guidance on acceptable levels. See our white paper Turn Down the Heavy Metal. To avoid these issues, use fertilizers designed specifically for hydroponics produced by reputable manufacturers.
- Recirculating runoff: In recirculating systems, check the runoff. Reused nutrient solutions can cause salt buildup or lead to deficiencies as certain elements are depleted faster than others.
Issue 3: Pests and diseases
Cannabis is susceptible to a number of pests and diseases that can compromise plant development, quality and yield.
Pathogens often flourish under the right environmental conditions. If disease is discovered, determine whether the grow room needs adjustment, such as reducing humidity. Don’t forget about storage conditions, either, where mold and mildew can also develop.
While some pest and disease problems are easy to spot (e.g., aphids, thrips, powdery mildew), others may not be. Follow Integrated Pest Management (IPM) best practices to check for issues. Manually scout the plants—even if your operation uses scouting technology—to verify its accuracy. Sticky cards, pheromone traps and indicator plants can also help detect pests and track populations. Keep in mind that finding pests isn’t always cause for concern if their numbers remain below threshold levels.
Issue 4: Contaminants
Contaminants[3] can pose health risks to consumers, potentially compromising the therapeutic value of cannabis-based medicines and the safety of recreational cannabis. These may include pathogens, pesticide residues, heavy metals, residual solvents or mycotoxins. For example, the mold Aspergillus can cause respiratory issues in people with compromised immune systems,[4] while Fusarium, another fungus, can produce mycotoxins that trigger vomiting.[5] Pesticides, if used, can also contaminate the final product.
Unfortunately, testing can be tricky, as labs may not be able to detect all contaminants, especially pesticide residues.[6] While some companies offer remediation solutions, there is limited peer-reviewed research confirming their efficacy. Prevention through best management practices remains the most effective way to limit contaminants. This includes following IPM protocols so pesticides are used only as a last resort, ensuring cannabis dries properly and keeping humidity in check during storage.
Issue 5: Product inconsistencies
Consistency is crucial to running a successful cannabis operation. To build a loyal customer base, growers need to ensure that recreational users enjoy a similar experience every time. Medicinal cannabis is treated like a pharmaceutical product and must meet strict regulatory standards.
Delivering a consistent product depends on consistency across the entire operation. In addition to environmental control, key factors include:
- Cannabis strain: A consistent consumer experience requires growing the same plant with the same genetics. Clones or tissue cultures from a mother plant ensure genetic uniformity and consistent metabolite profiles. Tissue culture offers the most reliability because its sterile environment helps eliminate inherited issues like disease.
- Pruning: Pruning not only redirects the plant’s energy into bud production but is also linked to greater chemical uniformity.[7] Inconsistent pruning, by contrast, can negatively affect the final product.
- Post-harvest care: Trimming and drying influence cannabinoid and terpene levels and can lead to significant differences in secondary metabolites. Standardize these processes to ensure they are consistent in technique and timing.
- Storage: Packaging and storage also matter. Exposure to humidity, temperature and light[8] can degrade cannabinoids. Ensure storage methods are correct and applied consistently.
Issue 6: Operational challenges
Sometimes errors occur and issues arise because we get too focused on the granular. While it’s important to pay attention to the details, it’s just as crucial to step back and get a big-picture view of the entire operation to make sure nothing is falling through the cracks. Common problems at the operational level include:
A standard operating procedure (SOP) is “a simple document that provides instructions on how to perform a routine or technical task that is followed by a business or industry.”[9] Clear, replicable SOPs ensure consistency in the grow room—which, as discussed, is essential for product consistency—while also reducing human error, saving time, minimizing costs and variables, and preventing avoidable setbacks. SOP templates and software can help with development.
Data is only as useful as it is accurate. Incomplete or incorrect data can lead to misinterpretations, misdiagnoses and poor decision-making. Consider using software tools that streamline data collection and analysis.
New solutions should be tested on a small scale before being rolled out across the entire operation. Conduct controlled trials where only one variable is changed and a control group is included. Use yield data, third-party lab results and qualitative evaluations—like bud aroma and effects—to draw conclusions. A careful, systematic approach to change enables informed decision-making.
Preventing problems
Not every challenge can be avoided, but there are many steps growers can take to prevent issues—or stop them from becoming bigger problems:
- Regularly monitor plants: Frequent, thorough inspections help catch issues early and fine-tune conditions to maximize yield and quality. Accurate, complete data allows growers to recognize patterns and spot problems sooner. If something goes wrong, records can help identify where the issue started.
- Source fertilizers from reputable brands: As discussed in the nutrient management section, fertilizer source matters. High-quality fertilizers designed specifically for hydroponic systems help maintain nutrient availability and avoid precipitation or negative interactions. Reputable manufacturers also ensure proper nutrient ratios and concentrations.
- Use a high-quality water source: We recommend reverse osmosis (RO) water, which removes pesticides, heavy metals and other toxins—creating a nearly pure input ideal for hydroponics. If RO isn’t an option, distilled water is a good alternative. Whatever source you choose, test it before use and monitor it regularly.
- Choose your strain(s) wisely: A plant’s genetics strongly influence growth and final product quality, so it’s important to choose the right one. Advertised cannabinoid levels don’t always match lab results, and donor plants may carry infections that suppress terpene levels. Run your own lab tests and trials before making major investments in a strain or cultivar.
- Automate the environment: Use automated sensors and systems to monitor and control key environmental variables—temperature, humidity, light, carbon dioxide, pH, moisture and nutrient concentration. Refer to VPD charts to confirm that conditions are optimal.
- Implement IPM: This strategy combines mechanical, physical and biological controls to prevent and manage pest and disease outbreaks. Follow its four steps: set threshold levels, monitor and identify risks, prevent outbreaks and use non-chemical solutions before turning to pesticides.
- Prioritize hygiene: Pathogens can spread quickly in tightly controlled systems. Make sure all inputs—seedlings, mother plants, media, water—are clean and healthy. Maintain good employee hygiene, too. Handwashing and sticky mats help prevent pests and pathogens from entering the grow room. Keeping plants healthy through good practices also helps them resist infection.
Plants are living organisms, and it’s impossible to control every factor that could harm them. But proactive practices reduce the odds of problems arising, and a systematic response gives growers the best chance to resolve issues quickly and effectively.
Emerald Harvest Team
[1] Trancoso, Ingrid, Guilherme A. R. de Souza, Paulo Ricardo dos Santos, et. al. 2022. “Cannabis sativa L.: Crop Management and Abiotic Factors That Affect Phytocannabinoid Production.” Agronomy 12 (7): 1492. https://doi.org/10.3390/agronomy12071492.
[2] Bok, Gwonjeong, Seungyong Hahm, Juhyung Shin, and Jongseok Park. 2023. “Optimizing Indoor Hemp Cultivation Efficiency Through Differential Day–Night Temperature Treatment.” Agronomy 13 (10): 2636. https://doi.org/10.3390/agronomy13102636.
[3] According to the Cambridge Dictionary, a contaminant is “a substance that pollutes, spoils or poisons something”: https://dictionary.cambridge.org/us/dictionary/english/contaminant, accessed on 29 May 2025.
[4] American Lung Association. 2024. “Marijuana and Lung Health.” Last updated September 9. https://www.lung.org/quit-smoking/smoking-facts/health-effects/marijuana-and-lung-health.
[5] Caspermeyer, Joe. 2024. “New Study Reveals High Levels of Toxins in Seized Cannabis from Arizona and California.” Arizona State University News, March 20. https://news.asu.edu/20250320-health-and-medicine-new-study-reveals-high-levels-toxins-seized-cannabis-arizona-and.
[6] Dryburgh, Laura M., Nanthi S. Bolan, Christopher P. L. Grof, et. al. 2018. “Cannabis Contaminants: Sources, Distribution, Human Toxicity and Pharmacologic Effects.” British Journal of Clinical Pharmacology 84 (11): 2468-2476. https://doi.org/10.1111/bcp.13695.
[7] Danziger, Nadav, and Nirit Bernstein. 2021. “Shape Matters: Plant Architecture Affects Chemical Uniformity in Large-Scale Medical Cannabis Plants.” Plants 10 (9): 1834. https://doi.org/10.3390/plants10091834.
[8] Birenboim, Matan, Daniel Chalupowicz, David Kenigsbuch, and Jakob A. Shimshoni. 2024. “Improved Long-Term Preservation of Cannabis Inflorescnece by Utilizing Integrated Pre-Harvest Hexanoic Acid Treatment and Optimal Post-Harvest Storage Conditions.” Plants 2024 13 (7): 992. https://doi.org/10.3390/plants13070992.
[9] Zangaro, Casey, Elizabeth Ferry, and Madonna Benjamin. 2020. “What Are Standard Operating Procedures, and Why Are They Important to the Swine Industry.” Michigan State University Extension, January 14. https://www.canr.msu.edu/news/what-are-standard-operating-procedures-and-why-are-they-important-to-the-swine-industry.
