Mastering matric potential

Factoring matric potential into cannabis cultivation

Factoring in matric potential not only helps cultivators identify the best substrate for their setup, but it can also impact various operational factors including labor and water use. High amounts of clay or organic matter, for example, typically mean a soil or substrate has a higher matric potential because the water is more tightly held. Substrates with a sandy composition, on the other hand, generally have lower matric potential because the water is held more loosely and drains more quickly.

Too much water can cause root rot and other issues, and too little water can cause plant stress and inhibit growth. Keeping tabs on matric potential can help growers get a handle on moisture, resulting in better plant health, yields, and quality.

Using matric potential to create an efficient irrigation strategy

An irrigation strategy that incorporates matric potential can lead to healthier cannabis plants and greater water efficiency. Following are some steps growers can take to get there:

• Get visibility into the root zone. Factoring in the matric potential of a substrate means understanding its water-holding capacity, which can guide a grower’s approach to irrigation. Precision substrate sensors like the TEROS ONE offer real-time insights into the overall root zone environment, giving cultivators the intelligence to determine when and how much to water their plants.
• Use data to monitor and adjust irrigations. Substrates with a high matric potential like Rockwool may not need frequent irrigation because the water is more readily available to plants. Coco coir and other substrates with lower matric potential might need more frequent irrigations to ensure plants have adequate moisture. With this baseline as a starting point, growers can use the data to keep tabs on moisture levels and overall conditions in the root zone, take pictures and log notes on plant response, then adjust shot sizes based on the generative or vegetative targets they’re looking to achieve.
• Try drip irrigation. Growers must work hard to prevent over- or under-watering, which can lead to significant problems. Having both an understanding of matric potential and access to real-time substrate data offers growers a better, more informed path to success than gauging a plant’s watering needs by lifting a pot. Using this intelligence to set up a reliable drip irrigation system allows growers to have precise control over the amount of water delivered to each plant across all growth phases.

Understanding and applying matric potential can transform a cultivator’s irrigation strategy and lead to healthier cannabis plants and more efficient use of water, labor, and other resources.

Dive more deeply into matric potential with these clips from episode 71, episode 92,  episode 98, and episode 102 of Office Hours.

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