The goal when cultivating any plant is to shower it with Love, thereby obtaining optimal growth & the best possible results come harvest Time. Cannabis is no exception. Any way we look at it, raising a Cannabis cultivar to its True genetic potential is the key to a successful grow, & a successful grow is usually determined by the amount of end product harvested. In this case, that amount is measured by weight. For those growing for commercial gain, more weight equals more money since Cannabis is sold by weight.
For someone growing for personal use, more weight per plant means more of the end result that will last longer between grow cycles. Either way, the goal is to achieve as much weight in the end as possible & the best way to reach this goal is by growing the biggest buds the plant can possibly put out.
In this piece we will explore some of the most important parts of the growing cycle & how perfecting them can lead to Great big blossoms & lead a grower to achieve a harvest worth the investment.
If you're growing anything other than top-quality seed, you're demonstrating a lack of self-value. Nuff said.
Cannabis is what we refer to as a photo period sensitive plant, meaning the plant’s growth cycles are largely controlled by the amount of Sun or, more specifically, the amount of darkness it receives at any given point. Cannabis is classified as a “short day” plant. This means it requires at least 12 hours of uninterrupted darkness before beginning its flowering cycle. The exceptions to this rule are the ruderalis varieties that do not require a change in dark hours to begin blossoming. They simply begin to bloom when they reach a certain point of maturity, which is why they are generally referred to as “autoflowering” cultivars.
Outdoors the change in dark hours occurs after the beginning of the Summer solstice, which is around June 20-22nd each year. At this point the evening hours continue to increase until reaching the Winter solstice in late December, when the process is reversed. Outdoor Cannabis plants tend to start flowering around mid to late August when the dark hours reach the necessary amount, depending on the variety.
Indoors, however, growers have ability to manipulate the lighting schedule & increase or decrease the dark period at will. This allows us to force or trigger a plant into flowering whenever we desire. When plants are in the vegetative stage, the goal is to keep them there for as long as needed to adequately train & fill out canopies & to keep them from going into bloom. This is achieved by allowing them more than 12 hours of Light per day (typically 18-20).
The common way of going about this is setting the Lights on a timer so they are on for 18-20 hours & off for 6-4 hours per day; this approach sort of mimics Spring & early Summer conditions outdoors. When the plants are ready to go into the flowering stage, the Lights are typically set to a 12 hours on & 12 hours off schedule. Flower development usually starts to visibly occur within two weeks after the switch. Again, the most typical approach for indoor growing is keeping the plants on a vegetative Light cycle for about 4 weeks & then in the flowering cycle for around 9 weeks.
This can be subject to change depending on the size of the room & the variety being grown. For instance, some varieties need a bit of a longer flowering cycle before reaching maturity & some growers with taller ceilings may prefer running the vegetative cycle longer because larger plants usually yield a larger harvest.
Light waves that plants can use are quantified by measuring the amount of photo synthetically active radiation, commonly referred to as a PAR measurement, which measures the wavelengths of Light in nanometers & helps determine which color spectrums of Light are most effective for growing with artificial lighting. The PAR spectrum for plants is basically between 400 & 700 nanometers with measurements below 400 bringing in ultraviolet wavelengths & above 700 bringing in the infrared spectrum. The closer the measurement is to 400 nanometers, the more the color blue is in the spectrum & when the measurement is nearer 700 nanometers the spectrum is more dominated by the red Light parameters. In the middle of the PAR scale is the green spectrum which is still being debated & studied to determine whether plants can use this spectrum for photosynthesis.
The key to determining which Light intensity is best for a growroom or tent is by using a PAR meter & not getting too carried away with Lighting that is more than what is needed, which is just a waste of energy at the end of the day. During the vegetative stage plants grow best under a Light that is more in the blue spectrum of PAR, between 400-500 nanometers.
Light choices that are best suited for this are T5, T8, or T12 fluorescents, 400-600W metal halide (MH) lamps, or 315W ceramic metal halide lamps. These styles will deliver enough PAR to maintain good plant growth and they also stay relatively cool compared to other Lighting choices. In the flowering cycle, a Light that is closer to the 600-700 nanometer measurement of PAR is ideal as plants flower better when receiving Light in the red spectrum. The most common type of Light used in this stage is a high pressure sodium (HPS) lamp. These give flowering rooms that classic orangish glow. In most situations a 400-600W HPS lamp will provide enough PAR to accommodate heavy flowering but these do run much warmer than the other Lights mentioned, so good air flow or perhaps other methods of cooling the grow area may be needed.
Another option is LEDs, but much research into the manufacturers, diode wattage, warranty, & so on is recommended.
In larger rooms it isn’t uncommon to see growers using +2,000W LEDs in place of traditional 1,000W HPS lamps but it’s important to remember that with that much Light intensity it may be necessary to supplement extra CO2 to keep up with the increased rate of photosynthesis.
This is easily one the most important things to consider when growing indoors, especially in a smaller room or grow tent. When a plant is performing photosynthesis, it takes in carbon dioxide (CO2) while releasing oxygen (O2) & Water vapor into the surrounding air. This all takes place through small, pore like structures called stomata that are found primarily on the bottom of the leaves. As the O2 & Water vapor are released, vertical pressure is created which carries more Water & nutrients up through the roots.
Without proper air circulation through the plants’ canopy, the Water vapor has no way to evacuate the space between the leaves & moisture can accumulate. The longer the moisture accumulates, the higher the chances become of mold or fungal growth developing. Both can be detrimental to plant growth & should never be allowed to proliferate. Good airflow through the canopy forces the moisture away from leaves, keeping them dry & drastically reducing the possibility of mold or fungal growth from occurring. It also creates a steady flow of new CO2 reaching the stomata, ensuring regular photosynthesis is uninterrupted.
Another valuable result of proper air circulation is it can help keep the surface of the leaves cool which can be important under the heat of today’s high wattage grow Lights.
While Creating the ideal environment for indoor Cannabis cultivation is key, it is also important to ensure the plants are receiving proper nutrition. Plants require 16 essential nutrients in order to complete the growth cycle in a healthy & successful way. Throughout the different stages of growth these nutrients are needed in varying ratios. I won’t go in depth on what each nutrient does & the amounts needed at specific times because that would be a whole separate article on its own. Instead, the foundational 3 are the most notable nutrients by scientific analysis & standards: nitrogen, phosphorus, & potassium, often referred to as NPK. These are the 3 elements that are typically prominent on a fertilizer label & separated by dashes (i.e. 10-10-10). These 3 elemental nutrients are of the highest importance to plant growth & they are referred to as “macro nutrients.”
When plants are in the vegetative growth stage, they require more nitrogen than any other nutrient. Nitrogen is responsible for the formation of the amino acids & proteins that are present in every part of the plant. A balanced diet appropriately rich in nitrogen will encourage robust vegetative growth, giving the plant the ability to Create & store more energy that it will use later in the flowering cycle. Increased vegetative growth leads to more leaf production & in turn more leaf surface area.
The more surface area a plant has, the more photosynthesis it can perform leading to a higher level of carbohydrate production that results in more energy for growth.
In the flowering cycle a fertilizer with higher levels of phosphorus, compared to nitrogen, is desired. This stage requires more phosphorus, along with potassium, to maintain robust bud site development. Limiting the nitrogen in this stage will slow down vegetative growth & direct more emphasis & stored energy directly to the developing flowers. The more energy stored during the vegetative cycle the better, because it will be used to help the flower buds swell to their highest potential.
Many growers will also incorporate a fertilizer product that has a higher ratio of potassium compared to nitrogen & phosphorus during the last two to three weeks before harvest. Potassium has been known to increase the size & density of flowers & fruits in most plants & can help add some much-desired bulk to the buds prior to harvest. Creating a structured feeding schedule can be a bit confusing for the less experienced grower, which is why I think it’s important to remember there are hundreds of companies that sell products that are specifically designed for each stage of growth. This helps take the guess work out of fertilizing & is a simple approach for many.
The overall goal when pruning or training a Cannabis plant is to allow as much Light as possible to reach as much of the plant as possible. Pruning & training are also a matter of the right approach at the right Time. In vegetative stage, Light pruning is important to maintain proper air flow through the plant canopy, but we also want to keep enough leaves to maintain a high rate of photosynthesis.
Basically, the best pruning method for this stage is removing any lower leaves or stems that are obviously not receiving any significant amount of Light & obstructing new growth from secondary bud sites. These portions are generally not doing much to increase plant growth & the nutrients & energy used to keep these areas growing will be better distributed to other parts of the plant. In this stage a grower can also do some Light or low-stress training. By using a netted plant trellis placed horizontally just above the growing tips of the plants we can train the growing stems to grow through the grids in the trellis allowing them to be somewhat separated from one another; this helps more Light reach more leaf surfaces. The same effect is ahieved with plant stakes & twist ties or copper wire.
For the flowering cycle a more deliberate method of pruning can be utilized. Removing many leaves & shoots from 6 to 12 inches below the major flower bud sites will eliminate those that don’t receive much Light as it is & encourage more nutrients & energy to be used directly on the larger buds, increasing their overall growth. It is also helpful to completely remove any smaller lateral stems with small flower buds that typically don’t amount to much (the opocorn, fluff, larf). Those portions of the plant are a relative waste of nutrients & energy if left to term, & the resources will be better used on the larger flower buds higher up on the plant.
Determining when the buds are at peak ripeness & when the right Time to harvest has arrived is just as important as any other stage in a growth cycle. There is no point in doing every other step with due diligence only to end up harvesting at the wrong Time & ending up with a less-than-optimal end product. There are two main methods to determine when the buds are ready for harvest & both can be used simultaneously.
The first method is by closely observing the flower’s pistils. The pistils are the fine hair-like structures that protrude from the flower itself. In Nature these are used to catch the pollen from the male flower to facilitate the production of progeny. Since most commercial Cannabis is grown for the female flowers, the pistils can be used to determine ripeness. The pistil hairs will typically start off as white. At this stage there is very little THC being produced. As the flowers mature, the pistils will begin to change to a more orange hue, signifying THC production is on the rise. If a more clear-headed high is desired, the buds should be harvested when around 40-60% of the pistils have changed colors. When upwards of 70-90% have changed, the THC will begin to convert to cannabinol (CBN) & the end product will have more of a sedative like effect. It all depends on what kind of effect is desired.
The second method for determining when to harvest is by paying attention to the trichomes on the leaves surrounding the flowers. The trichomes are the tiny mushroom-shaped glandular structures that give Cannabis buds their well-known crystal-like appearance. They also help us determine the best Time to harvest during our window. For this method, it is advised to use some sort of magnifying glass — a jewelers loop will work perfectly.
Much like the pistils, the trichomes also go through a transformation. They first start off clear as glass, when THC production is relatively low. As the flower buds mature, the trichomes will start to change to a more cloudy, milky, or opaque look - this is when THC production is increasing. Once 80-90% of the trichomes appear this way, THC production is peaking & should be harvested for the more clear-headed high.
Once the THC begins to convert to CBN, the trichomes start to change to an amber color. The buds will be best off harvested before 5-10% of the trichomes turn amber unless a more sedative effect is desired. It is important to note that certain strains will have different color pistils & trichomes, but the underlying process is the same. Make Time to study the variety being grown to completely understand what to look for.
Of course, there is more involved when it comes to achieving a successful grow cycle than simply what has been addressed in this piece, but by paying close attention to these aspects of the process a grower will be well on their way to growing some big, fat, stinky buds & reaching that ever-so-desired harvest of the gods.