Recently, the concept of crop steering has become a popular topic among cannabis cultivators. While some growers are familiar with crop steering, many are just now starting to adopt the techniques. Unfortunately, there’s little information published on crop steering for cannabis cultivation.
In this post, we’ll introduce you to the concept of cannabis crop steering. For a deeper dive, download our Growers Guide to Crop Steering that covers parameters and strategies, as developed by leading industry experts.
What is Crop Steering?
Cannabis plants have hormonal systems that regulate their growth in response to external stresses. The concept of crop steering is essentially the exploitation of these hormonal responses, by manipulating a controlled environment to achieve a desired outcome – like bigger yields.
When a plant puts most of its energy into producing leaves, and not much into flower formation, the plant is considered to be in vegetative growth. When a plant is focused on the development of flowers, it is considered to be in generative growth.
Growers must maintain proper plant balance, a defining concept in crop steering. At any point in the life cycle, the plant is either focusing on leaf and stem growth or on flower production. If the plant spends too much time in either, the plant balance will be skewed. And if the plant isn’t in balance, then it’s likely that production and quality will ultimately suffer.
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.
Check out our site visit to Pacific Growth to hear their crop steering journey:
Vegetative Growth
Vegetative growth is when stems and foliage are the predominant focus of the plant’s energy use and resulting growth. Generally speaking, mild growing conditions are best to stimulate vigorous leaf growth. Conditions that favor vegetative growth include lower electrical conductivity (EC), higher water content (WC), lower vapor pressure deficit (VPD), lower light intensity, and an overall stress-free environment.
Although cannabis vegetative growth is most notably associated with the phase between clone and flowering, it’s possible to use vegetative cues to nudge plants back into vegetative growth at any point in their lifecycle.
For instance, if you have compact, slow-growing flowering plants you can use climate and irrigation cues to inspire vegetative growth, and stretch the plants out.
Generative Growth
In generative growth, the plant’s energy is directed toward flower production. The plant slows down the growth of new foliage and reduces its stretching.
In contrast to the mild conditions that inspire vegetative growth, harsher summer-like conditions are the foundation of generative cues. Higher light intensity, lower substrate water content, higher EC, and higher VPD are all examples of ways to motivate generative growth in your crop.
Generative growth cues can be leveraged throughout the plant’s life cycle, not just in the flowering period. For instance, if you have plants in your veg room that are demonstrating signs of excessive vegetative growth, you can modify your climate and substrate to steer your plants to grow more generatively.
Vegetative vs Generative Growth
It’s important to understand the difference between generative and vegetative growth, because cannabis plants are either in one or the other at any given time.
When a plant puts most of its energy into producing leaves, and not much into flower formation, the plant is considered to be in vegetative growth. When a plant is focused on the development of flowers, it is considered to be in generative growth.
To maintain proper plant balance, at any point in the life cycle, the plant is either focusing on leaf and stem growth or flower production. If your plants are not in balance they will ultimately suffer from lower yields due to less than optimal vegetative conditions. Crop steering allows the cultivator to accurately nudge the plants between the two stages to optimize their hormonal response and plant balance.
When and How to Use Crop Steering
Crop steering can be done at any stage of growth to accomplish specific goals a grower might have. In the last few years, crop steering techniques have really taken off at indoor cultivation facilities. Growers have been exploring a mix of vegetive and generative steering throughout the cannabis flowering cycle to maintain plant balance.
Growers use generative steering to initiate the flowering cycle with the change in photoperiod. Once flowers have set, and after around the first defoliation, they will switch to a vegetative strategy to keep the plant healthy and increase the bulking of flowers.
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.
You should experiment with these strategies on each cultivar as they will react differently to the timely changes in environmental conditions. The way to track the steering cues and effects they have on your plants is through crop registration.
What’s happening in the Root Zone?
Cannabis roots play a vital role in the quality of the final product. Healthy roots sustain healthy growth, as the roots deliver water and nutrients to the plant. Root zone management is the consideration of irrigation strategy and the impact the strategy will have on specific properties in the root zone, such as water content (WC), temperature, and electrical conductivity (EC) in your substrate. It’s important to understand each of these root zone properties, and how changes will affect your plants.
Selecting a substrate is an important decision as it serves as a conduit for making water and nutrients available to the plant. Substrates like soil, coco mix, or rockwool cubes, all perform differently as they have widely differing physical properties, such as the ability to absorb and retain water. In order to know how much to irrigate and feed your cannabis plants, it’s helpful to have root zone technology deployed that provides visibility into the conditions in your substrate.
Root zone technology, such as sensors, monitor the substrate temperature, EC, and WC. Monitoring your root zone will give you crucial information, which when combined with diligent crop registration practices, can help you answer key questions like “What dryback am I achieving overnight?”, “How high can I run EC before inducing crop damage?”, “What is the temperature of my root zone compared to the ambient temperature?”
Crop Registration
Crop registration is the collection of detailed measurements for your crop, and is arguably the most important aspect of crop steering. Through diligent data collection, growers can track how their steering actions affect the plants and resulting yields. Common plant attributes that should be observed during crop registration are:
- Plant height
- Root development
- Stem diameter
- Internodal spacing
- Leaf color / Stem color
- Flower circumference
- Trichome attributes
- Plant vigor
By collecting data on these key performance indicators (KPIs) at a regular frequency, you can begin to make correlations about cause and effect. And ultimately, how potent, productive, or even how vulnerable a cultivar may be to disease and pests.
Crop Steering Technology
Advancements and innovation in cultivation technology supports the adoption of crop steering in the cannabis industry. Beyond data collection and analysis, growers can control and automate HVAC, lights, fans, irrigation, and fertigation systems. Through a combination of sensors, control systems, cultivation software, irrigation strategy, and crop registration, growers can now steer their crops to greater outcomes 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 our Growers Guide to Crop Steering. Developed with leading industry experts, it will provide you with the knowledge and key parameters necessary to begin experimenting with crop steering!
