biological crop steering

Vegetative vs Generative Growth: Crop Steering Fundamentals

by | Sep 9, 2021

biological crop steering
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Crop steering is taking the indoor cannabis industry by storm. But the techniques and principles are not well-covered online and few can call themselves experts in the emerging cultivation technique. In crop steering, cultivators refer to the two main plant growth cycles as Vegetative and Generative growth.

What is Crop Steering?

Crop steering is the science of manipulating a plant’s controlled environment to achieve a desired outcome, like higher yields or improved terpene profile. A defining principle in crop steering is the maintenance of proper plant balance.

When a plant is in its earlier stages of growth, energy is spent on producing leaves and stalks to increase plant size. Later in the growth cycle, plants turn their energy towards flower production. Hormonal responses direct the plant towards one of these two motives and plant balance is all about optimizing the timing and focus of plant production. Yields and quality suffer when the plant balance is skewed and spends too much time in either vegetative or generative growth.

Crop steering techniques involve monitoring all environmental conditions as well as root zone data, like nutrient runoff.

The goal in commercial cannabis production is to maximize yields by optimizing plant growth in each stage. With crop steering, plants are given the opportunity to produce only enough foliage and stems in vegetative growth to support vigorous flower production.

Vegetative Growth vs Generative Growth

Cannabis plants respond to external stimuli. Their hormonal responses trigger certain kinds of growth, vegetative and generative. A plant converts the light and nutrients provided into energy. Optimally routing that energy is what crop steering is all about.

Vegetative growth is commonly known to be the stage of growth between clone and flowering. However, one can signal to a plant, even during flowering, to go into vegetative growth. One example where this strategy makes sense is plants that might be smaller or slower to grow. Climate and irrigation data is tracked and the conditions adjusted to trigger hormonal response and inspire vegetative growth to stretch the plants out.

Vegetative growth needs milder conditions to stimulate vigorous leaf growth like:

  • lower electrical conductivity (EC)
  • higher water content (WC)
  • lower vapor pressure deficit (VPD)
  • lower light intensity
  • overall stress-free environment 

Generative growth, on the other hand, directs plant energy toward flower production. While vegetative growth thrives on mild conditions, generative growth kicks into action with harsher, summer-like conditions:

  • lower substrate water content (WC)
  • higher EC
  • higher VPD
  • higher light intensity

Cultivators can motivate generative growth in their crop at different times in the plant’s life cycle, not just during flowering. One example when generative cues might be leveraged is when plants in the veg room are demonstrating excessive growth.

Vertical farming for instance offers limited vertical room for the plants to grow. Halting further growth might also be necessary for certain genetics. In either case, you can modify the environmental conditions or the substrate levels to steer your plants towards more generative growth.

Some growers go back and forth between vegetative and generative techniques to maintain plant balance. Other growers maintain vegetative steering until the crop gets closer to harvest, then switch to a heavy generative steer to finish the crop.

Crop Registration

The way to track the steering cues and effects they have on your plants is through a process called crop registration. Detailed collection of data points about your plants and conditions is the basis of crop steering. By tracking all variables, growers can test steering adjustments and monitor their effects. Round after round, steering methodology becomes clearer and more precise.

Some common attributes that are monitored in crop steering initiatives are:

  • Plant height
  • Root development
  • Stem diameter
  • Internodal spacing
  • Leaf color / Stem color
  • Flower circumference
  • Trichome attributes
  • Plant vigor

Whether your goal is higher yields or higher percentage of terpenes, you can begin to correlate your steering actions with the final harvest results.

Hardware and Software

Advancements and innovation in cultivation technology supports the adoption of crop steering in the cannabis industry. Hardware like cutting edge LED lights, HVAC, irrigation and fertigation systems boost production and management of large-scale commercial cultivation facilities.

Through a combination of sensors, control systems, cultivation software, irrigation strategy, and crop registration, growers can steer their crops toward greater yields than ever before. 

To dig deeper into the concept of crop steering, and to get guidance on how to implement these techniques into your operation, download this free guide to crop steering. Developed with leading industry experts, it will provide you with the strategies and key parameters to jumpstart or evolve your crop steering experimentations.