There are countless nutrient options when it comes to growing cannabis. Therefore, it can be difficult for inexperienced growers to find the best choice for their plants. Arguably the biggest mistake new growers make is to turn this process into an overly complicated task. Ultimately, they spend significantly more time, effort, and cash than necessary.
If you think that nutrient options are confined to marijuana plants that grow in soil, you are wrong! There are also a variety of hydroponic options, which tend to muddy the waters for the uninitiated. But fear not! We’re here to provide an easy guide to selecting the best nutrients for growing marijuana and producing fantastic yields.
What Elements Does a Marijuana Plant Require for a Successful Growing Cycle?
Hydrogen, oxygen, and carbon are considered non-mineral essential plant elements. They are taken up by the plants in either gas or vapor form. In ideal growing conditions, fresh air and water will provide ample hydrogen, oxygen, and carbon. These are, of course, the basic building blocks of life.
There are 17 essential mineral elements for plant growth broken up into macro and microelements or nutrients.
The macronutrients required for plant growth are:
The first three nutrients listed above – Nitrogen (N), Phosphorus (P), and Potassium (K) – are the most crucial. If you purchase a bag of nutrients from a store, you should notice an N-P-K ratio listed on it.
The ideal ratio changes throughout the growth cycle of your marijuana plants. For instance, you need a higher proportion of N and K to P during the vegetative stage. A general rule of thumb is to remain close to a 3-1-3 (N-P-K) ratio for the first few weeks.
It is best to reduce the proportion of nitrogen to phosphorus and potassium during flowering compared to the ratio used during the vegetative stage. It is essential to lower the portion of N at this point. It can reduce bud development and promote vegetative growth instead of generative (also known as flowering) growth.
Maintaining higher proportions of P and K is critical when flowering. This is because the plants use larger amounts during the flowering stage than during the vegetative stage.
If a marijuana plant doesn’t receive enough of a nutrient, it will show signs of a deficiency. Let’s explore this issue in greater detail below.
What About Cannabis Nutrient Deficiencies?
Please note that most nutrient deficiencies are due to excessively high or low pH levels in your water. Ideally, soil-grown marijuana plants will have a pH of 6.0-7.0. The range drops to 5.5-6.5 if you use coco coir as a growing medium or if you are growing hydroponically. When the pH is at the wrong level, it reduces the plant’s ability to absorb these nutrients.
Calcium and magnesium are often overlooked when discussing the growth of the cannabis plant. It is common to find them together in a single Cal-Mag supplement, which generally contains iron as well. These nutrients are essential to the process of photosynthesis, which involves creating energy from light. Magnesium is particularly crucial for photosynthesis; it is the central atom in the chlorophyll molecule.
While marijuana plants don’t need a large amount of sulfur, it is still considered an essential macro element. As well as aiding enzyme formation, it helps to construct proteins. Sulfur is also pivotal in the development of chlorophyll molecules. If your plant is deficient in sulfur, calcium, magnesium, or iron, it can display symptoms like yellowing or dying leaves.
Besides the macro elements, there are several more elements needed in much lower amounts. A deficiency in any of the following microelements will negatively impact the health of your plants:
What Are Mobile and Immobile Nutrients?
Many novice growers are unaware that there are ‘mobile’ and ‘immobile’ nutrients. There are also primary, secondary, and micronutrients. The difference between mobile and immobile nutrients depends on whether they can be translocated once the marijuana plant assimilates them.
A mobile nutrient can move from one part of the plant to another as and when needed. If a plant has a mobile nutrient deficiency, parts of it accumulated in old leaves move to new leaves to make up for the shortfall. This is why the first sign of mobile nutrient deficiency appears in the oldest leaves at the plant’s base.
Immobile nutrients stay in the same place once the plant assimilates them. You will spot signs of immobile nutrient deficiency in young leaves near the plant’s top and outer branches.
Crucial Cannabis Nutrients and Deficiency Symptoms
Now, let’s take a look at 11 important nutrients for marijuana plants, along with symptoms of deficiency.
Nitrogen is one of the most common nutrients in cannabis, and growers are aware of its importance. Despite this fact, nitrogen deficiency is common. It plays a significant role in most plant functions, including amino acid production and photosynthesis. Although your plants need nitrogen throughout their life cycle, it is especially important during the vegetative stage.
You can correct a deficiency by purchasing fertilizer with the right NPK ratio. Quick treatments include urine and bat guano. If you spot a nitrogen deficiency, act fast because your plant’s yield will be significantly affected otherwise.
It is fairly unusual for marijuana plants to exhibit a phosphorus deficiency. One of the main reasons involves the pH of the water or growing medium going above 7.0. Your plants need phosphorus for photosynthesis. Phosphorus also helps the release of stored energy in carbohydrates.
If you allow a phosphorus deficiency to run amok, the effects are potentially devastating. Your plants will experience stunted growth, poor yields, and low resin production when they become mature. Make sure you use a fertilizer with a high amount of phosphorus or a bloom fertilizer.
Potassium is the last of the ‘big three.’ It aids the production and movement of carbohydrates and sugars. It also aids cell division and helps with water uptake, root growth, and transpiration. In essence, no potassium means no plant growth!
Despite its importance, potassium deficiencies are common. If you use a natural fertilizer such as bat guano, please note that potassium is the least abundant nutrient of the big three. Fixing major deficiencies requires a water-soluble fertilizer high in potassium.
Your marijuana plants need calcium, as it is a crucial aspect of cell integrity and overall growth. Calcium helps with the flow of nitrogen and sugars throughout your plants. It is unusual to experience calcium deficiency when plants are grown outdoors. However, it can happen when you grow them in plant mixes.
Certain types of water don’t include large amounts of calcium; this makes them a poor choice if using a hydroponic system. You can treat a deficiency by using a calcium-rich substance such as lime.
Magnesium is one of the most important secondary nutrients. It is rare to experience a magnesium deficiency when you grow weed outdoors. However, it is more common when you grow indoors or if you use a soilless medium. It is a crucial player in chlorophyll production. You must infuse your plant with magnesium immediately if you spot signs of deficiency.
Marijuana plants use magnesium in very high amounts. If you believe your plants aren’t getting enough, use Epsom salts to deal with the issue. Make sure you distinguish between an iron and magnesium deficiency. Otherwise, you could end up over-fertilizing your plants.
Although sulfur deficiencies are uncommon, they can occur if your fertilizer or soil doesn’t already have enough of it. Sulfur is an essential nutrient because it helps plant respiration and the synthesis and breakdown of fatty acids. If your soil or water has an excessively high pH, it could result in phosphorus loss. This is a major cause of sulfur deficiency.
Your marijuana plants require zinc for sugar and protein production. This nutrient is crucial for the formation and retention of chlorophyll. It is also necessary for strong stem growth. Zinc deficiencies in marijuana are relatively common and manifest in significant structural changes in your plant.
You will see twisted leaf blades on the plant’s new growth while the leaves’ veins turn yellow. In some instances, you will see an extremely pale-looking plant. During the flowering stage, the plants’ buds become distorted and twisted. A lack of zinc can result in a brittle plant. In general, zinc deficiency is also linked to a lack of iron and manganese. As a result, we recommend purchasing a micronutrient mix of all three.
Your marijuana plants only need a tiny amount of molybdenum, which means a deficiency in this micronutrient is rare. It plays a role in a pair of important enzyme systems that convert nitrate to ammonium.
Manganese deficiencies are relatively rare in marijuana plants. They are typically found in conjunction with zinc and iron deficiencies. This nutrient is important for creating nitrates and also for the production of chlorophyll. High soil pH or iron excess are also possible causes.
Your marijuana plants require iron to assist with chlorophyll production and reduce and assimilate nitrates and sulfates. Iron deficiency can be caused by excess levels of copper, zinc, or manganese.
Your marijuana plants only need copper in trace amounts. It is important in the reduction of oxygen while aiding the plant’s carbohydrate metabolism and nitrogen fixation. As your plants only require a tiny amount, it is relatively rare to see copper deficiencies.
However, it is important for reproduction and maturity. Therefore, you must give your plants something to help replenish their copper supplies. Copper fungicides can help to re-adjust copper levels in the soil.
Nutrient Deficiency Symptoms
- The plant’s older mature leaves will become lighter in color and eventually turn yellow. It is especially noticeable near the bottom of the plant.
- A failure to treat the initial nitrogen deficiency will result in further yellowing of the plant. Eventually, the entire plant will be affected by discoloration and brown spots at leaf margins.
- The leaves of your plants will start to curl and drop.
- You need to ensure your plant gets lots of nitrogen during the vegetative stage. Also, make sure it continues to get a reasonable amount during flowering. Otherwise, the plant will flower earlier, exhibit fewer bud sites, and yield less potent marijuana.
- Slow growth and dark leaf colors.
- Once the phosphorus deficiency threatens to get out of hand, upward and outward growth almost grinds to a halt. Dead spots will appear on petioles, and the plants’ leaves will curl and drop.
- It is also possible that leaves will turn dark bronze.
- Potassium deficiency is deceptive because it seems like your plants grow tall and vigorous at a glance. However, the bottom leaves could be dying.
- Overly green leaves with rusty brown tips.
- Dehydration, leaf burn, and the curling of younger leaves.
- Weak plants at high risk of being attacked by pests or stricken by disease.
- With magnesium deficiency, you’re unlikely to spot any signs for 3 to 6 weeks after it has started. At this stage, you’ll notice the veins of older leaves becoming yellow, with rust spots.
- Eventually, symptoms move through your whole plant. You can see larger spots visible in the interveinal areas, along with the leaves’ margins and tips.
- The plant will look sick, and leaves will start to curl up, die, and fall off.
- You will find that the signs of deficiency speed up during the flowering stage, which leads to a diminished harvest.
- The plant’s development slows, and the young leaves begin to turn a darker green color.
- The rate of flower production slows significantly.
- The plant’s root tips will wither and die. As a result, your crop’s yield is reduced.
- Large necrotic blotches on leaves that have become dark green.
- Newer leaves begin to turn lime green, then yellow.
- Stunted growth with narrow and brittle leaves.
- Slow and weak flower growth with reduced potency.
- The leaves of the plant turn 90 degrees sideways.
- The tips of the leaves become ‘burned’ and discolored, with brown spots arriving shortly afterward.
- New growth shows signs of interveinal chlorosis.
- The middle leaves begin to turn yellow.
- The shoots begin twisting, and you might see a red discoloration at the tips of the leaves.
- Occasionally, the leaves of your plants curl up before dying and dropping.
- It begins with interveinal chlorosis in new growth, which spreads to older leaves.
- The areas around the places where the plant is yellowing remain green.
- Young leaves and new shoots show a lighter green color than is normal.
- Chlorosis spreads to other leaves.
- These leaves become necrotic and eventually die.
- Necrosis in young leaves.
- A copper-like or bluish-gray color at the tips of the leaves.
- Limp flowers, leaves, and other parts of the plant.
What Are Hydroponic Cannabis Nutrients?
The hydroponic growing process involves growing marijuana plants without soil as the growth medium. Instead, you use a different substrate such as clay pebbles, Rockwool, or coco coir. Hydroponics is becoming an increasingly popular growing method because it offers potentially high yield using a small amount of space.
Due to the soaring popularity of hydroponics, the majority of nutrients sold for cannabis cultivation are now soluble fertilizers. These products consist of concentrated mineral salts available in powder or liquid form. Whatever option you choose, you dilute the nutrients in the water to the correct concentration before applying them to your plants.
There are separate products available for the vegetative and flowering stages that contain different N-P-K ratios.
For vegetative growth, choose a fertilizer with a higher proportion of nitrogen and potassium to phosphorus. When your plants are flowering, decrease your nitrogen concentration and increase the percentage of phosphorus and potassium.
One problem with hydroponic nutrients is that they can be very unforgiving if the incorrect dosage is applied. Follow the fertilizer bag or bottle recommendations and frequently check the pH to ensure it’s between 5.5 – 6.5.
Now, let’s examine fertilizer usage when using one of the three most popular hydroponics growing mediums.
This light and inexpensive mineral is known for its water retention abilities. It consists of a silica compound and basalt. You can buy it shredded, in small cubes and blocks, or large slabs.
If you purchase Rockwool, remember that it is an alkaline medium before it is conditioned with a lower pH solution. To condition the blocks before planting, soak them for at least an hour in water with a pH of 5.5.
In Rockwool, the elements you provide in the nutrient solution will be immediately available to your plant for growth.
This coconut fiber is a natural choice for a growing medium. It is made up of a coconut husk, the substrate used by coconut seeds to help them germinate.
Coco coir does an excellent job of retaining minerals and water. Its water retaining abilities are akin to Rockwool, but it’s recyclable and doesn’t cause damage to the lungs when inhaled.
Coco coir has a pH of 6.5 – 7.0, which is very close to unfertilized soil. It’s becoming increasingly common to add up to 30% perlite to coco coir to increase aeration around the root zone.
Overall, it does not have the buffering capacity that soil does, but it is more forgiving than alternative growing mediums. Ideally, you will keep the pH of your water and nutrient solution between 5.5 – 6.5 when using coco coir.
Growers recommend nutrient brands such as Dutch Master and Canada Advanced Nutrients when growing marijuana plants in coco coir. One final thing to note: Coco coir doesn’t retain calcium particularly well. Therefore, keep an eye out for any deficiencies and consider supplementing with extra calcium at all stages of growth.
Unlike Rockwool or coco coir, clay pellets don’t retain water well. However, you’ll find it easy to cycle nutrients and water without the age-old concern of overwatering your marijuana plants.
The gaps in clay pellets are ideal passages for nutrients and oxygen, which results in a robust root system. Best of all, clay pellets are reusable, so you can save money in the long term.
Soil Nutrients vs. Organics for Cannabis – Which Is Best?
The main difference between soil and the growing mediums used in hydroponics is the existence of organic matter. Examples of these include manure, worm castings, compost, and humus.
The majority of the essential elements contained in organic matter are only available in a non-soluble form. They have to be processed by the microbes and fungi in the soil to be available for plant uptake.
Non-organic fertilizers can be a quick and easy package to increase soil fertility for outdoor and indoor grows. However, these fertilizers can build up rapidly and diminish the quality of the soil. The buildup of these fertilizers can reduce a plant’s capacity to absorb water and nutrients.
In contrast, organic nutrients and fertilizers contain fewer soluble nutrients. They also help promote soil health by feeding the microbes and fungi that live in the soil.
Creating an Organic Fertilizer
A cheap and straightforward way to create your own fertilizer is to use organic inputs. Here are a few examples of organic options high in a specific nutrient:
- Nitrogen: Fish meal and blood meal.
- Potassium: Kelp meal and wood ash.
- Phosphorus: Bat guano and bone meal.
- Calcium & Magnesium: Dolomite lime.
- Sulfur & Magnesium: Epsom salts.
Suppose you’re able to mix these ingredients in the right amounts. In that case, your main tasks during the growth cycle involve watering your plants and adding carbohydrates to feed the microbial communities that occupy your soil. You can purchase premixed organic fertilizers, but these can be more expensive than mixing your own.
Final Thoughts on the Best Nutrients for Growing Cannabis
There are a remarkable number of ways to grow cannabis. Some involve hi-tech equipment, while others require vast experience and skills. Although it’s tempting to dive into the latest fads, remember that humans have been cultivating marijuana for thousands of years. Using little more than water and any organic option will help your soil. That being said, pay attention to any signs of nutrient deficiency and act as soon as possible.
Organic soil is recommended if you’re a newbie since it is more forgiving than growing hydroponically. Hydroponic nutrients help you produce enormous yields but require more time, expertise, and attention.
Above all else, analyze how much time and money you can afford when growing your marijuana plants. This is a great idea because it will save you time and money on products you won’t ultimately use.