Part I: Overview of the Plant Lifecycle
By Craig Allen and Nik Nikolayev
Welcome to the start of a discussion on plant happiness. We want to initiate a conversation within the cannabis growing community, so please, use this article as a starting point: take notes, discuss the topics with friends or colleagues. Collaboration can be a powerful tool.
We want plant nutrition to be as transparent as possible in the hope that you will walk into your garden and start having more fun and with more successful harvests. The plants you grow are incredible living beings, and as you uncover their secrets can open a vast world of possibilities.
It is helpful to think of a plant’s growth cycle in terms of three categories: environmental conditions, metabolism and pathology, and stages of growth.
– Environmental conditions describe the environment where the plant grows — air temperature, humidity, CO2, under what kind of lights and in what medium, whether that is soil, hydroponics, coco coir, etc.
– Symbiotic relationships refer to how plants interact with that environment. Plants interact in order to obtain carbon, water and nutrients via foliar sprays, soil drenches, etc. This category encompasses the good with the bad, including how the plant interacts with predatory insects, bacteria and fungi, etc.
– Plant growth addresses interactions within the plant throughout its lifespan from germination to harvest, including processes like photosynthesis and flower formation. Plant growth, of course, depends heavily on environmental and symbiotic conditions.
As you read on, remember: plants want to live. They will find any way possible to grow and propagate. You can make a thousand mistakes while growing your plants and somehow they will still form buds. If you shift your focus from succeeding more to failing less, you might be surprised with the outcome. For example, if your environment and symbiotic relationships are well balanced, it is difficult for plant chemistry to fail. Be organized and grow well.
All plants require nitrogen (N), phosphorus (P), potassium (K), and micronutrients from their environment, which is why all nutrient regimens contain these supplements. In fact, most premium nutrients utilize the same raw ingredients. Their differences lie solely in the ratios of those ingredients to each other — and on occasion there are a few fancy additives. As long as you have an appropriate balance of the elements the plant needs, you can choose whether to purchase your nutrient regimen from a single manufacturer or you can build it from mixed components off the shelf at your local shop. How those nutrients are used is more important than which brand you choose, because at the end of the day it is the gardener that grows the plants and not the nutrient program.
Optimizing the environment can be a complex task but it is based on simple components. The lights cannot be too bright or dim, the temperature cannot be too high or low, humidity cannot fluctuate between arid and tropical, and so on. Look for the sweet spot at which plants grow best, then figure out ways to keep the plants as close to that sweet spot as possible. With enough time, care and attention, you will quickly come to understand the nuances of your plants and find ways to drastically reduce failures.
Before we dive under the hood of your marijuana plants, it might be good for you to know where we are headed. We’ll start by looking at the plant life cycle beginning with the rooting conditions for cuttings. From there we will follow the plants growth needs into the vegetative state and on to early bloom. Once we have covered the interactions in early bloom, we will delve into mid-late bloom and harvest conditions.
Keep in mind that these general guidelines are meant to serve as a starting point. Every plant, gardener and grow facility is different, meaning the best way to grow your plants is yet to be discovered by you. We will point you in the right direction.
Optimal Rooting Conditions
Whether you take cuttings from mother plants or grow from seeds, your plants will first attempt to grow roots so that water can be transported into their first set of leaves for photosynthesis to occur. This process is beautifully complex and orchestrated by hormones. Hormones tell the plant what to do and how to grow from rooting to harvest, and without them, your plants would not grow any roots. No roots equals no way to solubilize, assimilate and utilize any nutrients.
Because they are so important to the rooting process, premium rooting compounds contain hormones, specifically, an auxin such as indole-3-acetic acid. Auxins are a class of hormone naturally produced in the new leaf growth of your plants. They travel down the leaves into the root zone; along the way, they pass important chemical messages throughout the plant, eventually stimulating the roots to grow. If leaves are healthy they will produce more auxins and that will stimulate the roots to get bigger and stronger so the leaves will get more nutrients so they can keep producing more auxins. This process is called a feedback loop, and it helps build a strong relationship between the roots and the canopy.
Rooting is arguably one of the most sensitive and delicate phases in a plants life. The plant’s defense mechanisms are not yet established to resist toxicity from overfeeding, overwatering, inadequate humidity levels, and so on. Therefore, when you take your cuttings, take them with care and follow informed, organized procedures. The health and final production of your grow can be greatly influenced by the way you interact with your plants in this first step. We have said for a long time that the entire process of growing marijuana hinges on getting your cuttings to root.
Cuttings taken at the correct time and cared for properly often have shorter rooting times, more balanced growth patterns, stronger immune systems, and can provide significantly higher yields as a result. If rooting times are reduced by more than four to five days, those extra days can be spent in vegetative growth and extra bud sites can form as a direct result. Additional bud sites on every plant in a room, plus shorter turnaround time between rooting and veg states can mean significant profit increases.
During veg, the roots will support the growth of the canopy. By being adventurous and exploring the soil, they can increase their total surface area with which to absorb water and nutrients. More surface area equals more nutrient uptake. More nutrient uptake equals more photosynthesis and faster growth.
Once your cutting’s roots have taken hold, a different set of growth hormones kick in: the cytokinins. These are produced in the root zone and travel up the stalk into the developing canopy. Once here, they will stimulate the shoots and stems to grow and develop new leaves. Cytokinins and auxins essentially work together to coordinate a significant majority of growth throughout the plant’s lifespan. As the root system and canopy are developing, they rely on both hormones, so when one of them is not functioning properly the whole plant can experience stress.
Plants will drink lots of water during vegetative growth to meet their demands for photosynthesis. As they process that water, the leaves push used water out of their pores, which creates a draw on the roots to pull new water from the soil — think of sucking on a straw. This flow is an important part of the photosynthetic process, so it is beneficial to make it easier for your plants. Proper humidity levels in the air of your grow room can act as a wick, helping to pull moisture out of the leaves and into the air. Lighting that is sufficient but not too intense can promote the transfer of water without evaporating it. In this way balanced humidity and gentle lighting levels in a room have a direct effect on root growth in the vegetative phase.
A week or two into vegetative growth, and your plant should be growing vigorously. Photosynthesis in the leaves is continuously converting atmospheric carbon into carbohydrates. It’s a pretty cool process which allows the plant to fuel its own growth. Some of what is produced in the leaves will travel down the stalk and be exchanged with bacteria living in the root zone for nutrients, like nitrogen. Some of those nutrients are crucial for photosynthesis to occur, so it is an interesting relationship that the plants have with bacteria. This subject will be addressed in more detail in the September issue of Marijuana Venture.
In vegetative growth, the general rule is that more sunlight equals more photosynthesis. However, more photosynthesis does not necessarily equal more growth. Remember the pores in the leaf we just discussed? Those open during the day to exhale water. When the lights are on they create a vacuum on the roots drawing water one direction, but at nighttime they close and the vacuum is essentially reversed. The fancy word for this is “hydraulic redistribution” and in simple terms it allows water to flow back to the roots where it can be used to solubilize and transport nutrients. So remember, even a couple hours of darkness for plants in vegetative growth can yield positive results — while photosynthesis does not occur in the dark, nutrient exchange does.
You might be wondering why there is a shift in nutrient movement when the sun goes down?
One simple explanation is that it supports a symbiotic relationship between the plant and beneficial bacteria and fungi. A good way to look at this is that the plant and the sun create certain compounds naturally through photosynthesis. These compounds are difficult for the root zone bacteria to make on their own, so they engineered a trade with the plant. The root zone bacteria produce compounds that the plant needs and has trouble making on its own. A perfect trade! It’s almost like these life forms evolved together.
In a nutshell, the goal in vegetative growth is to find the perfect balance of environmental conditions and symbiotic relationships so that you can grow strong, healthy plants that eat lots of sunlight. This will provide structure and capability for your plants to flower well, and hopefully yield a bumper crop.
Transitioning from vegetative to flowering growth is the next chapter in our story.
Late Vegetation and Early Flowering Conditions
The best way to hold gigantic buds upright is with thick, hearty stalks. Calcium and silica are your plants’ preferred elements for structural support because they are relatively hard when crystallized and provide a number of additional benefits. Calcium is critical for the plant overall because the role it plays in opening and closing the pores on the leaf that allow for photosynthesis. It also helps maintain a pressurized flow of water and nutrients throughout the plant, and is crucial for so many more reasons.
The benefits of silica in plant growth have only recently been discovered, and while it is not considered an essential element, there are many studies that show positive effects ranging from pest and disease control to increased uptake of amino acids. Silica can also increase the thickness of cell walls, making it harder for intense light to evaporate water from the inside of the leaf.
By the end of veg, you should have beautiful, healthy plants with thick stalks — and it’s time to change the light cycle. Flowering is such a complex process that to this day, it’s difficult for scientists to fully explain how plants do it. Nobody really knows what’s going on here, but we do know what nutrients are needed to make an excellent harvest.
It’s a pretty complex process, so to make it easier, we will divide flowering into two phases: bud formation and blooming. During formation, the plant will form small buds on the stalk that will become full flowers as it blooms. Buds develop and bloom into flowers as nutrients are assimilated and become cannabinoids, terpenes, and all the other good stuff we like. The whole process is known as flower morphology, but that’s more complex than we’ll get into for this first article.
Let’s just take a look at the basics here. First and foremost, the nutrient needs of the plant change dramatically from the vegetative stage. During vegetative growth, the plant primarily needed nitrogen for photosynthesis. During flowering, the plant is going to need more phosphorus and potassium because these two are required for flower formation. No phosphorus equals no THC.
You may notice that for at least a of couple days into the new light cycle, your plants lengthen and stretch out. In this phase, excess nitrogen is burned up and the plant opens up, allowing greater photosynthetic capacity and increasing total surface area for bud formation without focusing on new growth. Stalks will stretch comfortably where water leaves are nearby, because they can obtain nutrients from those leaves much more easily than they can if they draw up from the roots.
This early stage of flowering is when the plant needs the most phosphorus. Similar to the general truth in veg that more light equals more photosynthesis, the general truth in flower is that more phosphorus equals more flowers. However, don’t overdo it. Too much of any nutrient can cause a chemical burn in your plant. Scale up your phosphorous additive slowly and be mindful of the plant’s limits.
Mid-Late Flowering and Harvest Conditions
Cannabinoid synthesis is a pretty complex process that requires a lot of energy and nutrition. And anything that needs to be transported between the roots and the bud sites requires potassium. The more you want to move, the more potassium is needed to transport it all. This is important during flowering, when your plant is growing thick colas and juicy flowers. Cannabinoids can quickly accumulate into heavy compounds and so they require a lot of energy to move. If your potassium levels are low you will likely notice stunted growth and sluggish flower formation. We don’t want that — not after we spent so much time and care on these plants in rooting and veg.
About four to five weeks in, your plants are going to fill their flowers in densely and evenly if all of their nutritional needs have been met. You will see trichomes distributed evenly across flowers that look healthy, colorful and vibrant. You may also see leaves starting to turn yellow. Don’t worry — this is normal. At the end of the cannabis plant’s life, it will pull nutrients from the leaves and deposit them into the flowers. It’s an interesting concept known as nutrient remobilization, and makes sense for a number of reasons — most importantly that your plant is spending more of its resources on flower production than on maintaining canopy health.
Toward the end of their lives, you may also notice your plants drink less water and require fewer nutrients. This is perfectly natural. One common but semi-controversial practice during this period is called “flushing the plant.” For about 10 days before harvest, the plant is fed pure water and possibly a flushing agent. The idea is to prevent nutrients from accumulating inside the plant during this stage and ruining the taste of the final product when it is harvested and dried. There are ongoing debates on the legitimacy of this practice. We are of the opinion that the flavor of your bud is more strongly related to how you treat your plant over its entire lifespan than how you treat it during the final week or two of its growth.
When the trichomes on the buds have gone from translucent to milky to amber, it’s time to harvest. All of your time planning and executing strategy in your growing operation should be honored here. Make sure you spend an equal amount of energy harvesting well. Good plants harvested improperly are an expensive mistake, and a general disappointment. You’ve taken great care of your plants so far, so do a good job on this last mile.
Plants always strive to maximize efficiency, so the name of the game is to create pathways where the least amount of energy is required to transport the largest volume of water and nutrients. That is how you get the most growth from each day your plants are blooming.
Never forget the law of the minimum. All plant growth is governed by what is least available.
Try to get involved in your plant’s health. Call your nutrient company and ask the difficult questions. Keep investigating. If you don’t know the answer, someone you know probably does.
In our articles to come we will take a more in-depth look at both nutrient usage and plant chemistry.