Crop steering: The simple summary

What is crop steering?

Plants need light, water, and a place to grow. When cultivating in an indoor or greenhouse setting, it’s the grower’s job to create a nurturing environment  that mirrors nature as much as possible. This requires regularly monitoring and adjusting the lighting, irrigation, and other environmental factors in response to what the plants need.

Crop steering allows  cultivators to manipulate light, climate, and irrigation to encourage their plants to grow a certain way. Long used in hydroponic vegetable production, crop steering is achieved in part by adjusting the frequency and amount of irrigation specifically for the environment, cultivar, and stage of plant growth. This lets cultivators grow bigger, higher-quality plants and increase yields without cutting production.

How does crop steering work?

To achieve healthy cannabis plants in high yields, maintaining a proper balance between a plant’s vegetative and generative growth stages is vital. Growers can use crop-steering techniques to cue their plants to lean more heavily in one direction or the other.

It’s helpful to understand the life cycle of the cannabis plant:

1. Propagation: when a new plant grows from a seed, cutting, or tissue culture
2. Vegetative: when plants produce leaves, stalks, and shoots
3. Generative: when plants produce flowers, fruits, and seeds
4. Harvest: when plants are gathered and dried before curing

During the vegetative stage, plants are focused on early root and plant development. Growers must maintain proper water content in the root zone without over- or under-saturating the substrate. Crop steering  promotes rapid growth by eliminating stressors and allowing plants to absorb as much water as possible while also ensuring they receive adequate nutrition. This balance is achieved by keeping electrical conductivity (EC) low and using each irrigation event (shot) as a signal that encourages the plant to maximize resource uptake and growth.

During its generative stage, the cannabis plant focuses on maximizing flower, resin, and flavor production. While growers apply more shots throughout the day in this phase, water content is typically maintained at lower levels than during the vegetative phase. When steering generatively, growers apply targeted stressors including increasing EC in the irrigation and substrate to control water uptake. This promotes more compact growth with a greater focus on the parts of the plant that support reproduction.

Nimble responses to cues

Crop steering empowers growers to control their environment, make more informed cultivation decisions, and achieve targeted results. The following parameters are most important when steering crops:

• Electrical Conductivity (EC): The amount of dissolved fertilizer in a solution as determined by the ease at which electricity can move through the water; EC is a direct measure of the amount of water that roots can access immediately for transpiration and growth. For a deep dive into EC, check out our video.
• Drybacks: The difference in volumetric water content (VWC) - expressed as a decrease in VWC% - from the last irrigation event of a given day (maximum saturation) to the first irrigation event of the following day (lowest VWC level).
• Field capacity: The point after/during irrigation at which a substrate can no longer hold any more water. Check out this video for more about field capacity.
• Leachate: The solution that is not absorbed by the medium during an irrigation event once it has reached its maximum potential saturation; also known as runoff.
• Shot size: The volume applied during an irrigation event, or shot - usually expressed in total volume (mL) or as a percentage of the total media volume. For example: a “3% shot” means the volume of the irrigation water applied is equal to 3% of the total substrate volume.
• Volumetric Water Content (VWC): The volume of water per volume of substrate, expressed as a percentage (%). Check out this video for more on volumetric water content.
• Water Content (WC): The volume of nutrient solution (water + nutrients) in the substrate.

With sensors that see inside the substrate and a platform that tracks and monitors  growth at every stage, cultivators get the insights they need to steer their plants successfully.

For a deeper dive on this topic, check out the AROYA Guide to Crop Steering.

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