This is the first of a series of articles providing you all the information you need about marijuana nutrients problems and what you can do to make the problems go away. We’re starting with the most common nutrient problems and the ones that cause the most harm to your marijuana plants.
First off, some interesting, basic facts…
Your marijuana plants need 18 essential elements. They get carbon, hydrogen, and oxygen from atmosphere and water. They get the 15 other elements via their roots. These elements are sometimes grouped as major, secondary, and trace elements. The groupings are determined by how much of each element is needed–some are needed a lot more than others, but all are necessary.
The major elements are nitrogen, phosphorus, and potassium. The so-called secondary elements are magnesium, calcium, silicon, and sulfur. Some people group these seven elements as “macronutrients” because they’re required in larger weight amounts than the remaining essential elements your plants need. Those are called micronutrients, and they’re very important even though your plants don’t need as much of them. We’re talking about iron, zinc, copper, molybdenum, boron, manganese, cobalt, and chlorine.
Until recently, silicon wasn’t even included in the essential element list, but modern research on marijuana plants indicates your plants use silicon to build strong cell walls, resist pests and diseases, and to create THC glands.
Nutrients problems most likely to reduce growth rate, THC percentages, and harvest weight often involve nitrogen, phosphorus, potassium, and calcium. But problems with deficiency or excess of any of the 18 essential elements is likely to cause serious trouble for your marijuana plants.
How do you know your marijuana plants have nutrient deficiency or excess? Look at your leaves. If they’re not lime green, upright, and looking like the perfect marijuana leaf photo accompanying this article, your leaves are trying to tell you something.
But here’s a twist…it may not be your organic fertilizers, soil, or hydroponics nutrients that are actually causing the problem. Signs of nutrient element shortages or excess may merely be a symptom of the real cause of the problem. For example, low temperatures interfere with nutrient uptake. So you can’t solve a temperature-related nutrient deficiency problem by increasing your nutrients dosing…you solve the temperature problem instead, so your marijuana plants can take in what they need.
The Right Amount of Nitrogen
Makes Your Marijuana Healthy and Green
Nitrogen makes up 78% of the dry volume of our atmosphere and plants need to capture it if they want to grow at all.
No doubt you already know nitrogen is the big N in the N-P-K on your hydroponics nutrients bottles, and it’s a big, important ingredient for your marijuana growing success.
Unless your plants are in the final weeks of flowering phase, yellow leaves (especially lower leaves) are signs of trouble, and the troubles are most often a nitrogen deficiency. It starts with the bottom leaves and works its way up until only the newest growth is green.
On the other hand, if your marijuana plants are overdosing on nitrogen, the leaves will be extremely dark green.
Either way, nitrogen problems mean big trouble for your marijuana plants because nitrogen is absolutely necessary for plant survival because nitrogen is a primary elemental support for protein synthesis, growth, leaf development, metabolism, and root health.
If you oversupply nitrogen, you get marijuana plants that are too tall, thin, and gangly. It’s harder to get successful flowering from plants that have been overfed nitrogen.
If you see that the very tips of your leaves are yellow, that’s an almost sure sign of nitrogen deficiency, which occurs most often during a fast-moving grow phase or when you’ve switched to an improperly-configured bloom fertilizer during flowering. Many brands of hydroponics nutrients do not contain the right ratios of nitrogen, phosphorus, and potassium, or they contain the elements in forms that are not easily available to your marijuana plants.
These potential nutrients problems are especially harmful in flowering phase, when your plants only have 12 hours to run their photosynthesis metabolism.
Nitrogen deficiencies first show up as leaf tip yellowing, especially on lower leaves. Then it spreads to affect entire leaves, and moves up the plant. When you do research on marijuana strains before you buy seeds or clones, take note of the strains that are said to be heavy feeding. Those will likely want higher parts per million of nutrients, and they are hogs for eating nitrogen, potassium, and phosphorus. In bloom phase, your marijuana plants want less nitrogen, and more potassium and phosphorus.
The only time you tolerate signs of nitrogen deficiency is when you’re more than halfway through flowering phase. During those closing weeks, your marijuana plants are focusing on floral production so they sucks stored nitrogen out of leaves rather than doing the work of taking nitrogen in through the roots.
That’s why you don’t need to add extra nitrogen (beyond the amount found in a properly-configured flowering base nutrients product) to flowering crops after they’ve passed the midway point of flowering cycle: excess nitrogen during flowering negatively affects bud development, taste, and aroma.
Fixing Nutrients Problems to Save Your Marijuana Plants
In later articles in this series, you’ll see a more detailed program for analyzing and fixing marijuana nutrients problems but it’s important to understand a couple of things right away. One thing to know is that organic or “natural” fertilizers often fail to remediate a deficiency fast enough because they aren’t immediately bioavailable to your marijuana plants.
If you’re absolutely sure your marijuana root zone pH, grow environment, water, and other factors are what they should be, and your plants are still showing signs of nitrogen deficiency in soilless hydroponics marijuana growing, it almost has to be that something’s wrong with your base nutrients.
What are your remedies? If you’re growing in soilless hydroponics using synthetic hydroponics nutrients, you have it pretty easy.
First, make sure your pH meter is working perfectly (or use the new pH Perfect base nutrients that automatically buffer and adjust pH to the ideal sweet spot). Flush your plants (I prefer Final Phase or Flora Kleen), dump your reservoir, fill with reverse osmosis water, and feed with quality hydroponics base nutrients. When I say “quality hydroponics nutrients,” I mean a reliable brand of hydroponics base nutrients other than the brand you were using when the nutrients deficiency occurred.
You can also experiment with slight up and down adjustments of nutrients strength (ppm) or nutrients water pH and see if that corrects the problems. For example, many of us follow the dosage instructions on nutrients bottles and end up with 500+ ppm during flowering. In some cases, that’s too much, and what’s really strange is that using too much nutrients can result in nutrient deficiencies.
So try changing your dosage 50-100 ppm in either direction, and see if it makes a difference. Try adjusting you pH from 6.2 to 6.0. Different nutrients interact with root zone material and water differently, so that you might get absorption of 12 elements, but the pH is wrong for three other ones. Even small adjustments in pH (unless you’re using pH Perfect base nutrients in which case it doesn’t matter), can affect individual element’s absorption.
Just realize: it takes at least a couple of days for new root-fed nutrients, or changes in pH and ppm, to show up as fixes. In some cases, you might not see any changes in old growth…the only positive effects are in new growth.
If you have a severe nitrogen deficiency and you’re very worried about it, and if you’re in grow phase or pre-flowering, it’s best to mix a foliar spray containing a plant rescuer made with synthetic nitrogen, iron, and other nutrients(such as the product called “Revive”). That’s the fastest way to get emergency elements into your plants, and in some cases you can see the leaves green up in a few hours. Follow the foliar with a dose of Revive delivered via the roots.
Or if you’re past pre-flowering, use Revive only as a root dose. I don’t recommend spraying much of anything on marijuana plants that have established buds.
Unfortunately, if you’re growing marijuana in soil using organic or natural fertilizers it’s harder if not impossible to totally or quickly fix nitrogen problems and other nutrients problems. Your best bet is to use infused teas. Soil can produce kind marijuana, but consider taking a look at what one of my marijuana journalist colleagues has written about the complexities of growing marijuana in soil, and also be looking for the next in this series on fixing marijuana nutrients problems so you get fatter buds with more THC.