What is Crop Steering? A Definition
How Does Crop Steering Work?
Understanding Plant Growth Stages
Crop Registration
Harnessing Light, Climate, and Irrigation Cues
Lighting Strategy
Cannabis Crop Steering Chart
Tips on Choosing a Substrate
Tips for Crop Steering with Lighting
Tips for Crop Steering with Irrigation
Designing a Crop Steering System with Advanced Environmental Monitoring
Crop Steering Glossary
Cannabis crop steering is the next frontier of data-driven production. It's an indoor cultivation strategy that requires meticulous control over irrigation, lighting, and climate to apply specific environmental cues to drive plant growth. Crop steering promises growers better yields, larger flowers, and more predictable harvests.
Developed initially within the confines of traditional controlled environment agriculture (CEA), crop steering has quickly moved into the world of cannabis cultivation. As many cultivators have discovered, this strategy helps unlock a strain's full genetic potential by moving plants into and out of vegetative and generative growth phases.
What is crop steering in cannabis? How does it work? The following is a comprehensive review of the overarching strategy, a breakdown of irrigation, lighting and climate cues, and advanced crop steering tips.
Crop steering is an advanced method of growth management achieved by manipulating irrigation, fertigation, lighting, and other climate conditions to achieve the desired metabolic and hormonal changes inside the plant. It requires manipulating environmental and root-zone conditions to steer plant growth between two distinct channels: vegetative or generative.
By adjusting variables like light intensity, humidity, watering schedules, and nutrient concentrations, crop steering nudges plants between these two stress states. Vegetative steering is low stress, and generative steering is high stress.
Levering plants between high- and low-stress phases produces specific growth characteristics, like shorter or taller development, improved bud size, desirable cannabinoid profiles, and specific terpene expressions.
Crop steering cultivation is increasingly prevalent in the cannabis industry, where it is used to optimize plant growth, increase yields, and boost flower quality.
What is the fundamental principle behind crop steering? In short, stress.
By turning the knob between low-stress and high-stress conditions in the grow room, it's possible to induce predictable patterns of plant development.
But if we look beyond the bud, what is actually happening inside the plant in response to the grow room conditions? In part, crop steering is a play between two principles governing water movement: matric and osmotic potential.
Matric potential measures the energy plants require to extract water from the substrate. The substrate's physical characteristics, such as texture and structure, impact matric potential. This is especially pertinent in soil, a more variable substrate, because there is more wiggle room.
Osmotic potential governs a plant's water absorption capacity. It's influenced by the concentration of dissolved nutrients and salts inside the plant cells compared to the substrate.
Plants absorb water by maintaining a lower osmotic potential inside their cells than in the surrounding substrate. This encourages water and nutrients to move from the substrate into the plant, flowing from a high to a lower osmotic potential.
By playing around with the osmotic potential of the root zone, growers make it easier or harder for plants to absorb water and nutrients. This is yet another play between lower stress and higher stress conditions for the plant.
As an example from crop steering, growers may stimulate water stress through larger dry backs and/or increased electrical conductivity (EC) of the substrate to push plants into generative development.
The two modes of crop steering — generative and vegetative — should not be confused with the two conventional growth phases, veg and flower.
Plants still progress through the veg and flower stages of growth, but within these phases, cultivators manipulate the plants into more vegetative or generative development characteristics.
Let's look at an example:
Both vegetative and generative tactics can be applied during an eight-week flower stage. During the first four weeks of flower, when the goal is to limit vertical growth and shorten internodal spacing, growers apply high-stress conditions, aka generative cues.
In weeks five to seven of flower (once the flowers have formed), it's time to reduce plant stress by moving back into vegetative crop steering cues. This will encourage plants to increase bud size.
Again, generative and vegetative growth crop steering techniques are simply cultivation tactics that may be applied at any step of the production process to encourage specific growth patterns.
The precise manipulation of so many cues is only valuable if paired with intense grow room monitoring and plant data collection. In the crop steering world, the collection of plant-level data is called crop registration.
Crop registration requires the timely collection and analysis of detailed plant measurements to inform and optimize crop steering efforts. Every cue, whether it's irrigation, climatic conditions, or lighting, will trigger a related response from the plant, and crop registration aims to capture and document this data for better results.
The key performance indicators (KPIs) that are typically tracked include:
This data-driven approach helps identify optimal growth conditions for different cultivars, enhances productivity, and improves repeatability from one crop to the next.
Irrigation is a critical component in crop steering. Irrigation strategy governs the manipulation of three main principles: watering frequency, volume, and timing.
To move between vegetative and generative types of growth, cultivators work with different combinations of dry backs (the intervals between watering sessions), shots (the volume of water applied during any single irrigation event), and field capacity (the point during irrigation when the substrate cannot absorb any more water).
To encourage vegetative growth, irrigation must be frequent (e.g., every 30 minutes during light periods). This also encourages a lower substrate electrical conductivity (EC) because when combined with increased irrigation runoff, the concentration of nutrients in the substrate is diluted. In turn, this lowers EC levels. Together, these vegetative irrigation cues support a low-stress environment.
Transitioning to the generative phase, larger dry backs are applied, and the daily irrigation schedule is shortened. For example, watering might start two to four hours after lights on and conclude three to four hours before lights off, ensuring plants can transpire before receiving more water. During this phase, the goal is to slow down irrigation frequency, extend dryback periods, and maintain higher substrate EC levels.
Lighting cues are a longstanding cannabis cultivation tactic to guide cannabis through growth stages, from veg to flower. Flipping from an 18/6 schedule to a 12/12 tells cannabis plants that fall is right around the corner, indicating they need to move into reproductive development.
Yet, lighting also plays a role beyond the basic veg-flower flip. It is also a component of a more advanced crop steering strategy. Lighting intensity directly impacts plant stress, which in turn triggers vegetative and generative reactions in a plant's growth patterns.
Beyond photoperiod manipulation, growers can manipulate intensity and spectrum while also responding to strain-specific canopy heights to steer the crop further in the desired direction.
Lower light intensity can be applied (alongside higher water content, lower EC, and lower VPD) as yet another low-stress cue for vegetative growth.
Of course, lighting is also responsible for setting the photoperiod (lights on/lights off schedule). During the veg growth phase, a longer light schedule (18 on and six off) allows plants more time to absorb photosynthetic energy for greater vegetative growth.
To encourage a generative phase, growers shorten the photoperiod (12 on, 12 off). They can also apply higher-intensity lighting, lower water content, higher EC, and higher VPD cues. The latter creates a higher-stress growing environment.
Switching cannabis plants to a 12-hour light cycle from an 18-hour one signals plants to start budding. Increasing light intensity, which simulates late summer conditions, creates a more significant temperature drop between day and night, further encouraging flower.
Despite the fundamental role indoor lighting plays in manipulating plant growth under the crop steering mandate, lighting technology has remained frustratingly stagnant. Most options don't allow the type of zone-by-zone and precise control needed in a multi-strain grow room.
This is why the TSRgrow Zone Control, driven by remote power servers, is such a game changer.
Our advanced LED lighting technology has been decoupled from fixture-based drivers, allowing a innovative crop steering solution. Now, growers can customize lighting by zone and by strain to enhance total production potential and crop consistency.
Your substrate choice directly impacts a plant's ability to access water and nutrients. Each growing medium (coco, rockwool, or soil) has unique physical qualities, particularly their abilities to absorb and retain moisture, plus the subsequent effects over EC.
No matter what substrate you use, the only way to achieve the kind of meticulous control required for crop steering is through environmental monitoring, particularly root zone monitoring. Crop steering requires precise root zone scrutiny over the many variables, including EC, water content, and substrate temperature.
Coco coir has a naturally porous structure, facilitating more effective air and water exchange in the root zone. It also allows for a high cation-enhanced capacity (CEC). This means it is more effective than other substrates for exchanging and retaining positively charged nutrient ions with plant roots. This unique physical structure means coco coir has a greater capacity to hold essential nutrients, making them more available to the plants for uptake.
Rockwool, made from basaltic rock, retains water longer than other substrates. It offers a more linear water content curve, making it less forgiving than coco but beneficial once irrigation and environmental parameters are established. Interestingly, rockwool can absorb water more quickly than other substrates, even at low moisture levels.
Crop steering with soil is less common than with coco or rockwool but not entirely unheard of. Many craft growers are proponents of applying the principles of crop steering to living soil systems. Unlike coco and rockwool, soil isn't sterile, and its living biome impacts CEC, irrigation strategy, and dry back characteristics. There is a higher degree of variability when working with soil.
Most conversations about cannabis crop steering ignore lighting, at least beyond the basic photoperiod considerations. In part, this is because traditional lighting doesn't allow for the type of flexibility and zone-by-zone control crop steering requires.
Even most LED solutions are responsive to the room's environmental fluctuations. Yet, when irrigation and other crop steering cues are planned out minute by minute, shouldn't the lighting technology follow along with the nuances of the larger environment?
TSRgrow's advanced LED Grow Lights with Zone Control means growers now have meticulous control over lighting — no matter how many strains they have growing in the same room.
With our Zone Control LED lighting integrated into our TOTALgrow Solution approach, growers get unparalleled insight and management over the indoor environment on a zone-by-zone basis.
We've engineered this first-of-its-kind intelligent growth management platform for:
Irrigation cues are the cornerstone of most crop steering strategies. Typically, growers adopt a schedule that cycles through four phases of irrigation every 24 hours. The specific cues within each of the four phases vary depending on many factors, but the most critical is whether or not the grower is driving a high- or low-stress environment.
What are the four phases of irrigation in crop steering? Here are the basics:
This occurs between lights on and the first irrigation event.
It allows growers room for an additional dry back period and regulates when a plant begins transpiring. This phase effectively sets the plant's metabolism and growth direction for the day.
This phase occurs between the day's first irrigation event and when the substrate reaches its target volumetric water content (VWC%).
This phase does not happen in a single shot but through small, frequent waterings to ensure even distribution.
This occurs between when the substrate reaches maximum VWC% and the day's last irrigation event.
Phase Two aims to adjust substrate EC through tailored dry back percentages and irrigation shot sizes. Smaller, frequent irrigation shots promote runoff, aiding in salt flush-out and EC reduction, while larger, less frequent shots minimize runoff, increasing substrate EC. The duration and strategy guiding this phase vary, depending on plant size, water uptake capacity, and targeted dry back percentage.
This occurs between the last irrigation event of the day and until lights on the next morning.
During this time, substrate VWC% decreases as plants continue transpiring overnight. This phase intentionally subjects plants to mild drought stress, triggering specific hormonal responses.
The outcomes of tackling cannabis cultivation through crop steering will only be as good as the crop data — and analysis. Yet, despite how critical grow room monitoring plays in the equation, it fails to get the kind of attention it deserves.
How do you design the environmental monitoring component of a crop steering system?
It starts with GROWHub, TSRgrow’s award-winning cultivation software.
As we like to say, it's your autopilot solution to manage, track, and autonomously control your growing environment. Our platform connects four distinct elements into a centralized intuitive system:
Our wireless sensors can be deeply integrated into the grow room to monitor every aspect of the environment, including temperature, humidity, CO2, soil moisture, soil temperature, levels, VPD, and lighting (PAR and LUX).
Together, this real-time data helps build a master recipe for each strain, creating an environmental profile that can be replicated time and time again to achieve the full genetic potential of every strain in your portfolio and do so consistently.
Are you ready to elevate your production with advanced crop steering technology?
Contact a growing specialist today and learn more about the TSRgrow approach to cultivation.
Crop Registration: The collection and analysis of detailed plant growth data (height, stem diameter, root development, etc.) to inform and refine crop steering strategies
Crop Steering: A cultivation technique that manipulates environmental factors (light, water, nutrients) to guide a plant between vegetative and generative growth, optimizing yields and plant development
Dry Backs: Periods between watering when the substrate is allowed to partially dry, affecting root zone conditions and plant stress levels
Electrical Conductivity (EC): A measure of the salt concentration in the nutrient solution, indicating nutrient strength and affecting water uptake by plants
Field Capacity: The maximum amount of water a substrate can hold after excess water has drained away, important for ensuring optimal moisture levels for plant growth
Generative Growth: The phase of plant growth where energy is directed toward flowering and reproductive development, requiring higher stress environmental cues
Shot Size: The volume of water applied during an irrigation event, critical for managing moisture levels and nutrient delivery in the substrate
Water Content: The amount of water present in the substrate, influencing plant water availability and root zone conditions
Vegetative Growth: A phase focused on leaf, stem, and root development, where plants require specific low-stress cues to maximize growth without flowering
Volumetric Water Content (VWC): The percentage of water volume to the total volume of the substrate, used to gauge moisture levels for optimal plant growth