Cannabis, like all plants, needs water to survive. For growers who use crop steering techniques in the garden, an efficient irrigation strategy is crucial for achieving maximum yields and quality consistently and repeatedly. Drybacks, shot sizes, and other irrigation-related topics come up regularly during our weekly Office Hours podcast, and in this post, we’ll dig into a key concept that can help growers improve their irrigation strategy and optimize cannabis growth: matric potential.
Matric potential measures the energy required for plants to extract water from their grow medium, and indicates how tightly water is bound to the particles in the soil or substrate. Matric potential is directly influenced by the substrate’s composition and in a grower’s day-to-day, it tells them how easily their plants will be able to us use their roots to access the water available in the grow medium. High amounts of clay or organic matter 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. This distinction is important because 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.
Balancing substrate moisture for optimal plant health
Too much water can cause root rot and other issues, and too little water can cause plant stress and inhibit growth – that’s why growers must always work towards having a balanced approach to irrigation to ensure plants can thrive. Understanding and keeping tabs on matric potential can help growers get a handle on moisture, resulting in better plant health, yields, and quality in the long run.
An irrigation strategy that incorporates matric potential can lead to healthier cannabis plants and greater water efficiency – and here are some of the 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, and that can go a long way to 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 irrigations 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 by checking out these clips from episode 71, episode 92, episode 98, and episode 102 of Office Hours.