Nutrients For Cannabis: The Importance of Potassium To Grow Stunning Cannabis Plants

We have a special affinity for bananas — the fruit is easy to eat, cheap, and rich in potassium among other nutrients. A couple of bananas is often a good enough breakfast for college students! 

But you can’t feed bananas to your plant, can you? So, how do your plants get potassium? And more importantly, why does cannabis even need potassium in the first place? Let’s answer these questions in this article on the importance of potassium. 

The Significance of Nutrients in Cannabis Cultivation

Cannabis cultivation has transformed from small setups to a sophisticated agricultural practice driven by science and economic importance. Whether cultivated for recreational or industrial purposes, cannabis demands attention to detail to achieve top yields. This means that you should understand and fulfill the plant's requirements throughout its life stages from seedling to harvest. 

From providing proper lighting, maintaining temperature and humidity levels, and air circulation to using essential nutrients, everything is important. 

And, talking about nutrients, you need to be familiar with the top three macronutrients such as nitrogen, phosphorus, and potassium. For the purposes of this article, though, we will only talk about potassium and its importance in cannabis cultivation. 

But, before we talk about potassium, let's understand a bit about nutrients in general. They serve as the foundation of plant life as long as you maintain the right balance and provide only as much as the plants need. 

These essential nutrients are categorized into macronutrients and micronutrients, each with different roles in supporting the plant's growth and functions. Macronutrients, such as nitrogen (N), phosphorus (P), and potassium (K) — commonly known as NPK in fertilizers — are required in large quantities. On the other hand, micronutrients like iron (Fe) manganese (Mn) zinc (Zn) copper (Cu) molybdenum (Mo), and boron (B) are needed in tiny amounts but don’t underestimate their importance as the plants cannot function without them. 

All nutrients are important, but the star here is potassium. It’s vital for cannabis plants to produce buds but did you know that it’s also important for physiological processes like photosynthesis, water regulation, enzyme activation, and carbohydrate synthesis? The impact of potassium on these processes directly influences the health, growth rate, and ultimate yield of the plant.

Any deficiency or excess of these nutrients can disrupt the equilibrium and result in decreased yields and compromised product quality.

Therefore, even a basic understanding of the needs of cannabis plants is important so you can manage them easily. 

In the next few sections, we will explore potassium in detail and discuss its significance from identifying and rectifying deficiencies to employing the best approaches to maintaining optimal potassium levels for abundant yields.

Why Does Cannabis Need Potassium? 

Potassium is one of the three macronutrients for the cannabis plant, which is super important for your plant. That’s why it is found in all types of fertilizers for cannabis, including the PK boosters. Cannabis plants require potassium in adequate quantities for their overall growth and progress. Here’s an overview of how potassium helps in growing incredible cannabis plants.  

Photosynthesis: Plants cannot survive without photosynthesis. Potassium plays a role in this important process by regulating the stomata on the leaf surfaces. Potassium ions build up in the guard cells surrounding stomata, so they swell up and begin to open. However, on the flip side, when potassium levels drop, the guard cells contract and close. 

This mechanism ensures that the plants conduct photosynthesis efficiently, optimizing the plant's capacity to convert the energy they absorb from sunlight into chemical energy essential for growth and development. These stomata also control the exchange of gasses like carbon dioxide which is essential for photosynthesis and oxygen which exits as a byproduct. 

Water Regulation: Potassium helps the plants uptake water and also maintains the plant cell’s osmotic pressure. This process ensures that the plant cells remain firm and steady. So, if the plant has enough potassium, it can cope with water loss that occurs due to transpiration, particularly when it doesn't get much water.

Enzyme Activation: Potassium activates various enzymes that are important for many biochemical processes. It helps in synthesizing proteins, starches, and other vital compounds that are vital for the plant’s metabolic processes. 

Carbohydrate Synthesis and Transport: When photosynthesis occurs, the carbohydrates are synthesized in the leaf cells that are present in the chloroplasts. Potassium helps to transform these carbohydrates into forms the plants can use. In addition, it helps to transport them to other parts of the plant, including growing tissues. It contributes to the generation of adenosine triphosphate (ATP) which is crucial as the energy carrier in cells.  

In essence, while you may not find this element abundantly within the plant tissues, it does play various roles in the plant’s health and growth. Apart from the functions described above, potassium also makes the plant robust by improving the plant’s structural integrity. Along with phosphorus, it helps make the root system strong and hardy. In addition, it acts as an antifreeze for the sap, which increases the plant’s resistance to cold temperatures. And, finally, it boosts the weight and volume of the buds, leading to better harvests. 

No doubt, potassium is one of the most important nutrients your cannabis plant needs. 

The Cycle of Potassium in Nature 

Here’s the thing, potassium is abundant in soil. It exists primarily in minerals, though, but it is found in high concentrations in clay soils — they possess up to 3% potassium. Let’s take a look at how its natural cycle process works:

1. Potassium minerals are weathered and broken down, entering the soil and water systems 
2. Through rain and rivers, the element travels to the seas and oceans 
3. Water vapors carry potassium after evaporation and return to the land through precipitation 

At the same time, potassium can self-regenerate. When animals consume plants containing potassium, it is returned to the soil via excrement. Here, microbes process this potassium and make it available for the plants. 

However, this natural cycle can sometimes be an issue if you’re growing cannabis. If your region experiences heavy rains, the element can be easily leached from the soil, leading to potassium deficiency. Here, you may need to add potassium sulfate to the soil to replenish the nutrient. 

What Happens If Cannabis Plants Don’t Get Enough Potassium?

Potassium is a mobile element, meaning it moves from the oldest leaves to the youngest when needed, particularly where the plant’s metabolic activity is highest. When your cannabis plants are suffering from a potassium deficiency, you'll notice visible symptoms that help identify the issue. 

It's crucial to ensure your plants have enough potassium because a visible and advanced deficiency will have already reduced their production. But how do you spot the signs? Here are some common symptoms of potassium deficiency:

Yellowing Leaves: The first sign of potassium deficiency is when the leaves start turning yellow, beginning from the edges and progressing towards the center. This is usually more noticeable on leaves located at the lower parts. You may also see a yellow pattern emerging between the leaf veins, known as interveinal chlorosis. While the veins themselves often stay green, the tissue in between becomes yellow. 

Necrosis: As the deficiency worsens, the plant will display a lack of vigor. The yellowed areas on the leaves may transform into necrotic patches indicating death. These necrotic spots can spread, leading to curling and drying out of leaf edges.

Leaf Tip Burn: Severe potassium deficiency can give the leaves a scorched appearance as if the leaf tips and margins are burnt. This occurs because of the plants’ inability to effectively regulate water.

Weak Stems: Plants lacking potassium tend to have stems that are more susceptible to damage and struggle to support heavy buds effectively. If you bend them, they give away without any resistance. 

Stunted Growth: As you know already, potassium is crucial for photosynthesis. In addition, it plays a role in cell growth and division. Thus, when there's a deficiency, the plant's energy production is affected, so they don't grow as well as expected and stay smaller in size compared to other healthy plants that have enough potassium. 

Reduced Yields: The plant’s ability to produce energy and buds is reduced significantly, which is why you may notice a drastic reduction in yields. In addition, the plants produce significantly smaller buds as well. 

Increased Disease Vulnerability: Potassium helps strengthen cell walls and enhance plant immunity. Without that, plants become more susceptible to pests, diseases, and environmental pressures.

Causes of Potassium Deficiency in Cannabis Plants

Now that you know how to spot potassium deficiency, the next step is to fix the issue. But before that, you must learn the causes so you can nip it in the bud, pun not intended. Here are some of the causes of calcium deficiency in cannabis plants:

• Excess calcium in the soil, which can inhibit potassium uptake 
• Soil lacking clay or the organic matter in the soil failing to retain potassium 
• Overwatering, thereby flushing out potassium from the soil 
• Incorrect administration of fertilizers, which can lead to potassium deficiency 
• Lack of beneficial microbes in the soil, which would otherwise fix potassium for the plants to use 
• Incorrect pH of the soil, reducing potassium availability 
• Compacted soil, reducing the growth of roots and limiting nutrient uptake 

Fixing Potassium Deficiency in Cannabis Plants

Now let’s get to fixing potassium deficiency in your cannabis plant. It’s fairly easy, but you must do it right. Don’t wait around too long as a lack of potassium can seriously affect your cannabis plant. 

Here are some tips on fixing potassium deficiency in cannabis:

• Check the environment 

If you suspect the environment is at fault here, start by fixing that. So, check the soil quality. Sometimes, the soil doesn’t contain enough potassium. In that case, transplant your cannabis to different soil that is rich in potassium. 

You should also check the light panels and ensure they are set at the correct distance from the plant. Follow the manufacturer’s recommendations when determining the distance of the light. 

• Check and Fix the pH

Sometimes, your plant may fail to absorb potassium due to the soil being too acidic or alkaline. Here, you should use a pH pen to measure the pH of the nutrient solution and runoff water. 

You can then use a pH Up/Down solution to fix the pH of the nutrient water. If you're growing cannabis in the ground, perform tests on the soil to check the levels of potassium in the growing medium. You can use soil testing kits and ensure that the soil's pH falls within the range (6.0-7.0 for soil and 5.5-6.5 for hydroponics) as pH imbalances can impact absorption.

You also have to flush the soil to give it a good reset. For this, use pH-neutral water to flush the soil thoroughly and avoid feeding your plant any nutrients for a few days. 

• Use Bloom Boosters 

You can use bloom boosters that are rich in potassium and phosphorus with lower concentrations of nutrients. These boosters are excellent for flowering cannabis plants suffering from a lack of potassium. 

Don’t cheap out here and follow the manufacturer’s instructions on using them. However, you should still be more conservative initially to ensure your plant does not experience toxicity. 

• Or Use Other Products 

You can also use various other potassium boosters like banana peel tea, wood ash, bone meal, or kelp meal to give your cannabis plant a potassium boost.

But, sometimes, it can be too much. 

Excessive Potassium Levels in Cannabis

While potassium toxicity in cannabis plants is not as common as deficiency, it can still pose a threat. Yes, it’s a macronutrient and your plant needs it, but you shouldn’t overfeed it. Excess potassium can lead to various issues for your cannabis plant. However, identifying the signs and symptoms can help you minimize negative effects. 

Key indicators of potassium toxicity include:

• Leaf Discoloration

An abundance of potassium darkens the edges of leaves. Initially, the leaf tips and marginal may look brown, but as the toxicity advances, this discoloration spreads, leading to necrosis and brittleness in affected areas. 

You can confuse this with leaf burn as the leaves also look crispy over time. But, ultimately, the leaves die, and the plant struggles. One difference between leaf burn and toxicity is that leaf burn affects the top parts of the plant or the leaves that are closer to the light. The damage pattern often matches the intensity and direction of your grow light. 

It is usually caused due to environmental factors like light, heat stress, or exposure to artificial lights that are too intense. It can also happen when you spray the plants when the lights are on, leaving residue on the leaves.

Typically, leaf burn will have a few leaves with browning or scorching at the tips and edges of leaves. The damage is usually uniform and limited to areas directly affected by the stressor while the rest of the leaf may stay relatively healthy.

However, potassium toxicity affects the lower parts where excess potassium tends to accumulate. It can spread throughout the plant, and not just in areas exposed to light or heat. When excess potassium disrupts the plant's absorption, it can cause a range of deficiencies to occur.

• Interveinal Chlorosis

Excessive potassium levels can also trigger chlorosis in cannabis plants, where the areas between veins turn yellow while the veins themselves stay green. Again, you'll see this on the lower leaves initially, but you can confuse this with magnesium deficiency. Look for a yellowing pattern between the veins on leaves indicating issues with nutrient transport due to an excess of potassium.

• Nutrient Imbalances

Magnesium deficiency: An abundance of potassium competes with magnesium for nutrient absorption, leading to a deficiency in magnesium. Signs include yellowing or curling leaves but it usually starts from the lower leaves and moves upwards along with chlorosis.

Calcium deficiency: Elevated levels of potassium can hinder calcium uptake, so the stems become weak as their structural integrity is compromised. Symptoms of calcium deficiency include distorted or crinkled growth and an increased vulnerability to physical damage.

• Stunted Growth

Over time, plants may display stunted growth due to their inability to efficiently absorb essential nutrients. This can result in weak plants that don't form many buds. Even if they do, the buds will be inferior in quality. 

In addition, the overall vitality of the plant is affected, leading to a slowdown in growth. The plant's resources are redirected towards dealing with the imbalance rather than supporting healthy growth and bud formation.

• Weak Stems and Branches

Excessive potassium can weaken the plant and the stems and branches become fragile and prone to breakage. This is especially concerning during the flowering phase when the plant bears the weight of developing buds. And, since the stems and branches become brittle, they can break easily under pressure, so the yields will reduce as well. 

How to Fix Potassium Toxicity in Cannabis Plants

Potassium toxicity symptoms can vary based on your cannabis plant’s variety and growing environment. So, you must keep a close eye on your plant’s health. Fortunately, potassium deficiency is not too common in cannabis plants as mentioned already, and the problem is easy to fix. 

But, you can do so only if you identify the symptoms on time. Here are a few ways to make sure you can help your plants recover:

• To manage potassium toxicity, it's important to take action by flushing the growing medium with pH-balanced water when symptoms appear. You can also use enzymes that help break down salts during this process. 

This process helps remove potassium from the soil or hydroponic setup, restoring a nutrient balance for the plant's roots to recover. Depending on how severe the toxicity is, multiple flushes may be required, so keep an eye on the plant's progress. You must also ensure that you don’t cause another problem by overwatering the plants. After washing, follow up by watering with a light fertilizer, ensuring you adjust the pH to match your plant’s current growth stage. 

This approach will help your plant recover and restore its nutrient balance. Or, cut back on potassium fertilizers until the symptoms improve to prevent a buildup of potassium in the plant’s growing medium. Also, consider the plant's growth phase as cannabis plants typically require more potassium during their pre-flowering and flowering stages.

• Rather than trying to make your own fertilizers from scratch, especially if you're a beginner, look for balanced fertilizers containing all necessary nutrients while avoiding an overabundance of potassium. Good fertilizers will specify the NPK ratio clearly. You can even go for fertilizers that tell you what to use according to the plant's stage of growth. Lastly, pick fertilizers specially formulated for cannabis and tailored to meet its needs. 
• If you're growing in hydroponic systems, regularly test the nutrient solutions to maintain proper nutrient ratios. Use an EC meter to check the levels of the nutrients and do it on a bi-weekly basis depending on the growth phase and requirements of the plant. If the concentration is too high, dilute the solution or adjust the feeding schedule to lower the intake of potassium.
• If you're growing in the soil where you're planting your plants directly in the ground, you should conduct soil tests to determine the levels of nutrients and make adjustments. These tests indicate the composition of nutrients in the soil and help identify any imbalances. If the soil has excessive potassium, use nutrients that are low in potassium to compensate and maintain balanced nutrient levels. This step is crucial in preventing the accumulation of potassium in the soil. You can use compost or vermicompost as they provide a balanced nutrient profile without an excess of potassium.
• Your growing medium should be able to drain excess water easily to avoid overwatering, clogging, and nutrient imbalances. Poor drainage can result in waterlogged conditions that worsen issues related to toxicity. To avoid this, you can use aerated soil mixes with excellent drainage properties. Alternatively, you can add perlite, vermiculite, or sand to enhance soil structure and promote drainage. Also, make sure that the containers you use can drain water. 
• Just like you'd do this to prevent a deficiency, check the pH levels and maintain the appropriate range to make sure toxicity doesn't occur. Check the pH levels of both the growing medium and nutrient solution using a pH meter. This ensures that nutrients are effectively absorbed and helps prevent any imbalances.

How Much Potassium Do Cannabis Plants Need?

This totally depends on your goals. However, according to experienced growers, the recommended potassium rate is between 40 to 80 ppm K. Yes, these figures are lower than what you’d think is the industry standard. For example, many growers prefer using 60 to 120 ppm for their cannabis plants. 

Also, if you’re cloning your cannabis plant, stick to a higher concentration of 80 to 100 ppm. This will help your clone grow properly. And if you want high-quality cannabis buds, something around 60 ppm may suffice for optimal cannabinoid concentration. 

You can always experiment with both ranges and find what works best for you. Ideally, try to use plenty of potassium — to a point where it’s safe and doesn’t cause toxicity in your plant. This especially applies during the early stages of your plant’s growth. 

Remember, these numbers are a guideline, and the actual number that works for your cannabis plant may vary. So, experiment a little with your plant to find the sweet spot of concentration. 

Since you’ll be purchasing nutrients and will need to know the ratios according to the stage of growth, here’s a quick overview:

• Seedling stage: Cannabis plants don't need you to provide nutrients at this stage as the cotyledons take care of their needs at least for the first couple of weeks. However, if you feed them, make note that they need a balanced mix of nutrients with little potassium. In fact, you should only feed a little of all nutrients because if you overdo it even with small amounts, the seedlings can experience nutrient burn and die. You can use just a quarter strength of what's suggested by the manufacturer to see whether your plants are okay with it. 
• Vegetative Stage: In this stage, cannabis plants grow leaves, stems, and roots. Potassium plays a role in cell division and growth as you already know, so it's best to use a mix with more nitrogen but adequate potassium like 3-1-1 or 3-1-2 NPK. 
• Early Flowering Stage: As the plants transition into flowering, they will need more phosphorus and potassium to support bud development. As you know, higher potassium levels aid in carbohydrate synthesis and even transport them to different parts of the plant, and this is important for bud growth. A nutrient ratio of 1-3-2 (N P K) or similar with increased potassium is ideal during this phase.
• Late Flowering Stage: In this stage, maintaining proper potassium levels helps the plants develop thick potent buds. Thus, a nutrient blend with potassium levels like 0-2-3 or 0-3-3 (N P K) is commonly applied. 

You don’t have to do this on your own, though. Simply purchase a well-balanced nutrient blend that gives you proper instructions. Typically, the “bloom” part of the fertilizer will contain more potassium and you just have to follow the instructions to feed the plant. 

Sources of Potassium for Cannabis Plants

Here are a few options that can help you provide potassium to your plants.

Natural Sources

1. Compost: Packed with organic material and essential nutrients, compost gradually releases potassium as it breaks down, enriching the soil's fertility.
2. Wood Ash: Wood ash contains soluble potassium. However, using too much can make the soil alkaline, so use it sparingly. 
3. Kelp and Seaweed: These oceanic plants are abundant in potassium and other essential trace minerals. Whether you apply kelp meal or its liquid alternative, it serves as a great potassium source while promoting overall soil well-being.
4. Banana Peels: Available easily, banana peels are an excellent source of potassium and while you can use it raw, you can also use its composted form for great results. 

Synthetic Sources

1. Potassium Sulfate (K₂SO₄): As one of the most common potassium fertilizers, this synthetic fertilizer delivers potassium without introducing excessive chloride content that can be detrimental in large quantities.
2. Potassium Nitrate (KNO₃); Provides a combination of both nitrogen and potassium during the plant’s vegetative phase when these nutrients are vital.
3. Potassium Chloride (KCl) is a cheap potassium option that's widely accessible. However, its high chloride content requires cautious handling to prevent potential toxicity issues.

How to Prevent Potassium Deficiency in Cannabis Plants

Preventing potassium deficiency in cannabis plants doesn't require you to do anything special. All you have to do is take the right steps and adopt a proper approach to manage the nutrients you feed. Here are a few things to consider:

• Using Balanced Fertilizers

Opt for fertilizers that have a balanced NPK ratio suitable for your plant’s specific growing stage. We have mentioned the NPK ratios you can use, so you can use that information when purchasing nutrients. Also, apply fertilizers as per the manufacturer's guidelines to maintain a balance of nutrient levels in the growing medium.

If you're growing in soil, make sure it's fertile. If not, add components like compost and a bit of wood ash (don't overdo it) to introduce some potassium to the soil. Compost releases potassium and many other nutrients steadily over time. Not only does it help with potassium but also enhances soil quality, improves water retention, and supports root development for nutrient absorption. Therefore, make sure you have some compost at hand when growing cannabis. 

You can also use kelp meal or liquid kelp extracts to make sure that your cannabis plants never face a dearth of potassium. Kelp also offers trace minerals and growth hormones, so it's a great addition. 

Apart from that, you can integrate slow-release fertilizers into the soil when planting but don’t use other fertilizers when you use these as that could be overkill. These fertilizers release nutrients gradually over time, ensuring a steady supply of potassium and other vital elements.

Finally, maintain the right pH of the growing medium, whether it's soil or a hydroponic solution. If it's not in the right range, adjust the pH as needed. 

• Water your Plants Properly 

Avoid overwatering because excess water can cause nutrient leaching where important nutrients like potassium are washed away from the roots. Let the soil dry slightly between waterings to promote root growth and nutrient absorption.

Ensure that the soil stays consistently moist without becoming waterlogged. Also, do not underwater as constant dehydration is never a good thing. 

• Regularly Check on your Plant's Health

Look closely at your plants for signs of potassium deficiency such as yellowing or browning leaf edges, slow growth, and other symptoms. Detecting issues early allows you to take action promptly.

Keep notes of your fertilizing routine, watering schedule, and any symptoms you notice. This information is valuable for spotting trends and adjusting your care routine accordingly.

• Optimizing Growth Conditions

It's important to maintain proper temperature and humidity levels to grow healthy cannabis plants. Also, make sure your plants get light based on their growth stage. Good lighting helps with photosynthesis and nutrient absorption which are essential for plant growth.

Environmental stress can impact how plants absorb nutrients and their overall well-being. Thus, if you don't pay attention to these factors, your plants will suffer even if they have enough potassium. 

• Enhancing Soil Health

Having a thriving soil ecosystem is key to keeping your cannabis plants healthy. This means that your soil should be full of beneficial microbes that help the roots absorb adequate nutrition. 

Summary: Nutrients For Cannabis: The Importance of Potassium To Grow Stunning Cannabis Plants

And there you have it, folks! Ensuring your cannabis plants get enough potassium is like giving them the secret sauce to thrive. Remember, while you might love a potassium-packed banana, your plants need a more refined touch. 

Too little and they'll struggle, too much and they might get a bit overwhelmed. Keep experimenting to find that sweet spot and watch your cannabis flourish. After all, a well-fed plant is a happy plant!