Cannabis Canopy Management For Maximum Output
Manipulating your crop’s canopy to achieve maximum yields requires good note taking and an understanding of the species you are growing and the environment you have created for it. If you are operating a commercial grow, it also requires good communication by your team. Ben Burkhardt draws from his experience to provide best canopy management practices.
As gardeners gain the experience of seeing many crops grown to completion, they develop a perspective that allows them to anticipate what a plant will become based upon its genotype and structure, even when it’s in the early vegetative stage. This allows for precise control of the flowering canopy structure well before the plants reach flower.
Encouraging gardeners to record notes on each batch, take a detailed visual assessment of each completed batch before harvest, and perhaps even take a photo to jog the memory, is recommended. Seeing the result of a crop or batch, viewing the related data and making adjustments that will in theory improve the previous result is the best method of increasing canopy output and efficiencies.
Sharing accurate yield data is crucial and that information should drive the decisions made regarding gardening technique and logistics. If operating a commercial grow, I recommend having a full-time employee just to assemble the data from the garden. If the garden is large and the vegetative and flowering growth is managed separately by different departments, there should be strong communication and the end result of the vegetative team’s effectiveness of plant contortion and pruning should be studied and constantly improved.
The three-dimensional structure of the flowering canopy consists of square footage and depth. If growing medium size plants, the bud sites can be productive several feet into the canopy. The nuances of specific genetics lead to varying results, as certain examples will grow taller with better light penetration through the canopy due to skinny sativa dominant leaves, or may generate worthwhile flowers in a limited light condition.
Topping, or pruning, is the practice of removing the tip of a branch to encourage lower growth and to inhibit a plant from stretching. It also creates more primary nodes that will add additional flower sites by allowing the lower branches to catch up in vertical growth closer to the light. Although often abused, this is the most common example of contorting a plant for optimal yield.
Like all plant contortion techniques, topping is inevitably plant count and strain specific. Many genetics will grow vertically, with an overly large central cola, creating the likelihood of bud mold and reduced yields due to a limited amount of bud sites positioned close enough to the light. If executed at the right time, to the correct degree and with adequate lighting, topping a plant once or twice is usually all that’s required.
Once a cutting has been propagated for a few weeks and is beginning aggressive vertical growth, it should receive its initial topping, which forces the lower branches to catch up vertically with the central primary node before the plant has grown large, making it the most efficient time to do so. This typically results in three or four primary nodes, which may or may not be adequate, depending upon the crop’s growth structure and plant density per square foot. When more nodes are required, it is recommended to top in the vegetative stage once more, doubling them from six to eight.
Topping is additionally effective when the flower room is full and plants need to be held in the vegetative stage longer than necessary. Although this may cause smaller top flowers and more branches to manage than necessary to achieve the desired yield from the upper canopy, without cutting them back, they may become unruly, starched specimens that are unsuitable for maximum output. If done correctly during vegetative growth, topping won’t be necessary once the plants transition to flowering.
Freshly grown branch plant material is rather pliable, allowing a gardener to gently bend the stalks in the opposite direction requiring it to work to correct itself and allow lower branches to catch up vertically, allowing for superior exposure to light. Another option is to ‘knuckle’ the branch by making an aggressive bend that creates a 90-degree near-break in a branch that then will heal and drastically reduce that branch’s vertical growth, maintaining its node sites rather than removing the branches. It’s usually used for damage control once things are getting out of hand vertically in flower.
The best practice for limiting unwanted vertical growth after minimal topping is to utilize high PAR, or light intensity, to prevent the plant’s upper branches from reaching toward the light, as they are saturated already. This results in the plant being forced to focus growth on thicker, stronger branches and increased vertical height on the lower branches, while still allowing for the stresses plant material close to the light to heal with no consequence once in flower.
This is extremely effective in allowing shorter plants within a batch to catch up with the rest for an even canopy as well. While some lights are now equipped with dimming capabilities, the other option is to manually adjust the height of your light to the desired distance above the plants. Although PAR meters aren’t necessary to accomplish this, they can be a useful tool to dial in exact light intensity and study nuances across the garden.
While often best to use the lower canopy to maximize yield, inevitably there will be some branches exposed to limited light. As a result, they are weak and unusable for any worthwhile flower production. These will be removed as they are a waste of the plant’s energy and susceptible to pests and disease. The technique of ‘lollipopping’ is the practice of removing lower branches with the purpose of focusing more of the plant’s energy to the higher, more productive nodes.
While effective, it is important to be conscious of the balance required, allowing the useful branches to remain, while removing the rest. It’s common for gardeners to be overly aggressive, underestimating the potential output of the lower branches. The number of lower branches that are useful will be strain-specific, as some genetics have wider leaves, affecting light penetration through the canopy, and specific genetics possess varying abilities to have useful flower production in lower light conditions at the bottom of the canopy.
A specific strain’s growth pattern and structure will dictate how it should best be vegetatively contorted. This is accomplished by considering the key factors that influence the creation of an optimal canopy: growth pattern, plant density, ability to flower on low-lit branches and the explosive initial vertical growth in flower. A well-constructed canopy is instrumental in increasing yields while reducing the cost of production.