Macro and Micronutrients in Cannabis Cultivation

If you're new to growing, no worries. I'm here to make sure you’re fully equipped to handle cannabis macronutrients and cannabis micronutrients like a pro, even if you’ve never touched a weed plant before.

Micronutrients and Macronutrients in Cannabis

Let’s break it down nice and simple. Cannabis macronutrients are like the main course for your cannabis plants. These are the nutrients weed plants need in larger amounts to grow big and strong. You’ve probably heard of the main three—Nitrogen (N), Phosphorus (P), and Potassium (K)—which are often referred to as the NPK ratio. Think of these as the essential building blocks. Learning to understand this NPK ratio for cannabis early on will save you a lot of headaches further down the line in your grow journey. Trust me on this: they are crucial and fundamental.

Cannabis micronutrients, on the other hand, are needed in smaller doses but are still super important. These are like supplemental vitamins and minerals for your plants. You don’t need much, but without them, things can go sideways.

Let’s dig into the details and figure out how these macro and micronutrients work together to make your cannabis thrive.

If you want to get the best nutrients for your plants, below you can find our own Cannabis Fertilizer, available from ILGM.com.

Where Do Cannabis Plants Get Macronutrients From?

So, where do cannabis plants get all these essential macronutrients? Let’s take a closer look:

From Air and Water

Your cannabis plant is actually pretty resourceful. It can pull some of the essential macronutrients straight from the air and water, including:

• Carbon (C): Plants absorb carbon dioxide from the air through tiny pores called stomata. Carbon in the form of CO2 is used in photosynthesis to create energy and growth.

• Hydrogen (H): This comes from water. When your plant absorbs water, it splits the hydrogen to use for building plant tissues.

• Oxygen (O): Plants absorb oxygen from the air and water, using it in respiration to release energy stored in sugars. The roots also need oxygen from the soil to stay healthy.

From Soil

Other key macronutrients—like nitrogen, phosphorus, potassium, and secondary macronutrients— are taken in through the soil. You can add rich organic cannabis nutrients or you can add fertilizers to make sure your plant gets what it needs.

Primary Macronutrients (NPK)

Nitrogen (N)

Nitrogen is your plant’s growth machine. It helps build strong leaves and stems, keeping everything nice and green. Your cannabis needs nitrogen most during the vegetative stage when it’s focused on growing bigger. If your plant starts turning yellow, especially in the older leaves, that may be a sign that it is lacking nitrogen.

But too much nitrogen? That’ll give you big leafy plants with airy buds. So, you’ll want to keep an eye on how much your plant is getting, especially once it starts to flower.

Phosphorus (P)

Phosphorus is your plant’s energy booster. It helps with everything from root development to bud production. In the early stages, phosphorus gives your plants the strength to grow deep roots, and later on, it helps build those fat buds you’re waiting for. If there’s a phosphorus deficiency in cannabis, growth will slow down, leaves might turn purple, and the buds won’t fully develop.

Potassium (K)

Potassium is like your plant’s immune system. It keeps things running smoothly, helping with water regulation, disease resistance, and overall health. When your plant is in the flowering stage, potassium is essential for bud development and quality.

If you notice burnt tips on your leaves or edges turning brown, that’s usually a sign your plant is missing potassium. During flowering, potassium helps to produce denser, more resin-packed buds—so, yeah, it’s pretty important.

Secondary Macronutrients

Besides the big three, your cannabis also needs secondary macronutrients. These are needed in smaller amounts compared to the NPK ratios for cannabis, but they’re still essential to keep your plants happy and healthy.

Calcium (Ca)

Calcium helps keep your plant’s cell walls strong, giving it structure and resilience. Think of it as building strong bones for your plants. It’s an immobile nutrient, meaning it can’t move around within the plant once it’s absorbed. So, if you’re seeing problems with new growth—like brown spots or curled leaves—it might be a calcium deficiency.

Magnesium (Mg)

Magnesium is the powerhouse behind photosynthesis, making it absolutely essential for capturing sunlight and turning it into food. Without magnesium, your plant’s leaves will start to turn yellow between the veins, a sure sign that it’s not getting enough of what it needs to make chlorophyll. Since it’s a mobile nutrient, your plant can move magnesium to where it’s needed most—usually the newer leaves.

Sulfur (S)

Sulfur helps your plants build proteins and enzymes. You don’t need a lot of it, but it’s still crucial for plant metabolism and growth. If your plant is deficient in sulfur, you’ll see yellowing leaves, similar to a nitrogen deficiency, but starting with the newer growth instead.

Cannabis Micronutrients

Now, let’s talk about cannabis micronutrients. They’re needed in much smaller amounts, but don’t underestimate them—they still play a big role in plant health. Here’s what your cannabis will need:

Boron (B)

Boron is essential for building strong cell walls. Without it, your plant can become weak and fragile. Boron also helps with nutrient movement inside the plant, especially during growth spurts.

Copper (Cu)

Copper helps your plants with photosynthesis and also aids in carbohydrate and protein metabolism. If your plant is low on copper, you might see bluish or purple-tinted leaves on the new growth.

Iron (Fe)

Iron is crucial for producing chlorophyll, which helps your plant capture light energy. A lack of iron usually shows up as yellow or light colored leaves, starting with the youngest leaves at the top of the plant first.

Manganese (Mn)

Manganese helps with nitrogen metabolism and photosynthesis. It’s also key for reproduction, aiding in pollen development and seed formation.

Molybdenum (Mo)

Molybdenum helps your plant turn nitrogen into a form it can use for growth. If your plant is low on molybdenum, the leaf edges might turn yellow or curl.

Zinc (Zn)

Zinc is important for metabolic reactions and growth regulation. Without it, your plant’s growth might be stunted, and you’ll see newer, smaller leaves yellowing in color.

Mobile and Immobile Nutrients

Here’s a handy tip for figuring out nutrient deficiencies: some nutrients are mobile, meaning the plant can move them around to where they’re needed. Others are immobile, which means once they’re in a part of the plant, they stay there.

• Mobile nutrients: These include nitrogen, phosphorus, and potassium. Deficiencies in mobile nutrients usually show up in older leaves first because the plant is moving these nutrients to new growth.

• Immobile nutrients: These include calcium and sulfur. Deficiencies show up in the new growth because the plant can’t move these nutrients from older leaves.

Overfeeding, Underfeeding, and pH Levels

Getting your cannabis nutrient balance right can feel a bit like walking a tightrope. Too much or too little, and your plant will let you know. Luckily, there are some great nutrient lines that provide balanced nutrition. Try ours for instance and simply follow the dosage recommendations on the back of the package.

• Overfeeding: More isn’t always better. Don’t be a “more-on”. Too many nutrients can cause nutrient burn, which can look like brown or crispy leaf tips. Excess nutrients can also cause a nutrient lockout, where your plant can’t absorb any more nutrients because there’s a buildup in the soil.

• Underfeeding: On the other hand, underfeeding leads to deficiencies. You’ll see things like yellowing leaves, poor growth, or small buds if your plant isn’t getting enough food.

Finally, don’t forget about pH levels. If the pH of your soil or water is off, your plant won’t be able to absorb nutrients properly, even if you’re feeding it the right amount. For cannabis grown in soil, aim for a pH of 6.3 to 7.0. In hydroponics, keep it between 5.7 and 6.0. Keeping your pH in check is key to healthy nutrient uptake.

Final Thought on Cannabis Plant Nutrients

I’ve tried to keep this information as simple as possible, but there’s still a good chance you are feeling overwhelmed at this point. All I can say is, yeah, it is a lot, and it is complex. But, also, trust me when I say that this is important stuff to understand, and yes, it will get easier over time. Simply because you will see terms like NPK, cannabis micronutrients, and organic cannabis nutrients throughout your cannabis grow journey. Just like the nutrients into soil, it will all slowly sink in for you as you grow.