Accidents happen. Whether you're a beginner grower, or a cannabis cultivation expert, issues like surprise pollination, root rot, and cal mag lockout can still rear their crop-killing heads. Doing the best for your grow, no matter your level of expertise, will always be a rewarding challenge if you're doing it right, and that's because cannabis has such unique needs!
During the seedling stage, cannabis needs close light to avoid becoming leggy, and can do well with an ordinary white bulb! As it grows through its vegetative stage, you'll need to change that bulb to a blue-heavy one, and move it further away to prevent light burn. Yet later, you want a red-heavy spectrum to encourage bigger, stickier buds with a higher concentration of cannabinoids!
Similarly, your cannabis needs different amounts of light as it grows, if you aren't growing autoflower strains. Every kind of cannabis needs to have intense lighting, but harvests are only possible when their schedule is flipped! Outdoor growers don't have a need to simulate the seasons, as the sun and movement of the Earth do that for them, but indoor growers need to move to a set schedule for each stage of growth to get their buds to bloom at all. 16-24 hours of light in the vegetative stage is standard for most strains, but flipping to flower requires a move to 12 hours of darkness and 12 hours of that red-heavy light.
Cannabis is a fast-growing and hardy plant in general, but the ditchweed that grows through all sorts of adverse conditions in some parts is not the same as the plants you wish to harvest for yourself. Non-feral cannabis requires certain levels of humidity, consistent observation to prevent pests, quarantine periods, tool sanitization, air flow for healthy vegetation, and adequate ventilation! There are grow tents and grow cabinets that meet those needs–and some set ups that don't, and every grower has to make that determination.
Nutrition needs also vary in different stages! If you're starting from seed, it's very possible to put seedlings in soil that's "too hot" for them–meaning the overabundance of nitrogen is deleterious to the tiny plants. Meanwhile, that same soil might have nitrogen levels under what a towering flowering plant would need later in life.
Furthermore, no matter what medium you're growing in, hydroponic or soil, a PH level that's too acidic or too basic will also lead to lockout of several nutrients. Cannabis prefers a level between 5.8 and 6.2, and any conditions too far outside of this range will need to be corrected in order to keep your grow not only at its best, but alive in the first place.
Lockout of any nutrient is caused by an inability of the cannabis to uptake those nutrients from its medium and use them effectively. Though lockout causes deficiencies, the biggest difference between these two issues is that a deficiency can be caused by lack of supplementation. Lockout occurs when the nutrients in question are actually present in the medium, but are not being absorbed by the cannabis.
The unique needs we discussed not being met are how lockouts can occur–a stressed plant, like many stressed people, can't eat! Nutrient burn occurs when the opposite happens, and we'll cover that topic in a later blog.
Macronutrients are nutrients that plants need in larger qualities in order to thrive! Human macronutrients are complex nutrients made of multiple compounds like fats, and carbs, but plants like cannabis have the narrower specificities of certain elements made into very simple chemical components.
Carbon, Oxygen, and Hydrogen are technically macronutrients–the biggest any plant needs! But if you remember your eighth grade biology, you'll realize you don't need supplementary nutrients to get these essentials to your grow. They're literally the components of air and water! Carbon dioxide (CO2) and water (H2O) provide all the supermacros that your cannabis needs–and while there are certainly environments in which your grow wouldn't get as much as they need, no additional supplementation is needed for these elements in particular.
The primary macronutrients are Nitrogen, Potassium, and Phosphorus. You'll recognize these elements from the NPK on most bags of soil and nutrients. They're essential for regulating metabolism, water intake regulation, and root growth respectively, and as the name suggests, they're needed in the largest quantities.
The secondary macronutrients are Calcium, Magnesium, and Sulfur. Though they're not afforded primary status, they're far from unimportant! Without these minerals, plants wouldn't be able to form chlorophyll, cell walls, or strong root structures.
One of the biggest issues new cultivators must face is overcoming misconceptions based on non-scientific uses of certain terms in regular life. If there are primary and secondary macronutrients, they must be more important than micronutrients, right? Wrong! The only difference is in the concentrations of each mineral that plants need! Make no mistake, micronutrients are still vital to the health of your cannabis, and the potency of your future harvests. The best nutrients for cannabis will have a healthy balance of all of them!
The micronutrients cannabis needs are:
Boron - another cell wall building element that keeps plants upright and firm.
Iron - maker of chloroplasts– the cells that let your cannabis turn light into food.
Copper - a metal that allows for protein metabolism
Zinc - responsible for the hormone production that signals your cannabis to create certain structures (leaves, buds, and seeds if you're unlucky).
Molybdenum - key in synthesizing amino acids, translating them into what cells need to be constructed. Think of this element as the blueprints as your plants grow!
Manganese - creates reproductive structures–ie the parts of the plants we're here for!
Calcium and Magnesium are macronutrients, therefore there's a need for a higher concentration of these two minerals in the nutrients these plants uptake. But what are they past that?
Calcium is an alkaline earth metal–one of six powdery, silver-colored metals that react strongly with water, melt easily, and are found in abundance naturally in various compounds.
Calcium wasn't isolated as an element until the 1800s, but it was known to many peoples around the world in many forms as the primary element in many regular items. It's present in limestone, pearls, chalk, and areas with naturally hard water, as well as in milk, bones, and cruciferous vegetables.
It's number 20 on the periodic table, the fifth most abundant element in soils all over the world, and was first isolated by Humphry Davy in 1808.
It's just as essential for humans as it is for cannabis–regulating our muscles in motion, playing a part in blood clotting, and making up a good part of our skeletons. Unlike cannabis, an over abundance getting locked out isn't an option for humans–and kidney stones and tonsil stones are also made of calcified material.
What calcium does for cannabis is very similar to its function in our own bodies. Cell walls are the plant equivalent of skeletons–providing structure and firmness. Hormone regulation is its secondary job–but as an immobile nutrient (meaning once it's metabolized in one location, it stays there), its primary job is to be a building block.
Cannabis needs between 150 and 300 ppm of its medium to be an absorption-worthy source of calcium (bone meal won't be absorbed in the less-acidic soil that cannabis needs), and as a macronutrient, this mineral is a non negotiable component for healthy growth through the plant's entire life.