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Cannabis plants can suffer from a range of nutrient and mineral deficiencies. Some can have profound and even disastrous consequences on the plant.
One common deficiency found in marijuana is a lack of potassium. Typically occurring during the plant’s flowering stage, this can be deadly.
Therefore, you want to find the symptoms early and treat them as soon as possible.
If you notice one or two leaves starting to turn yellow, you shouldn’t worry too much. But, this could be a sign of the early onset of potassium deficiency.
If more leaves start to turn yellow, it means the deficiency is progressing. Therefore, you will need to find some solutions to the problem.
In today’s post, we are going to talk you through what a potassium deficiency in marijuana plants looks like. We will also discuss methods of treating it, so your plant can develop and grow healthily again.
The Symptoms Of A Potassium Deficiency In Cannabis
There are several signs to keep an eye out for to see if your cannabis plant has a potassium deficiency. The ways in which such a deficiency manifests tend not to be similar to one another.
Because of this, some people mistake potassium deficiency with other mineral deficiencies, such as magnesium, or even nutrient burn.
One of the main signs can be found on the lower and middle leaves.
If they have started to turn yellow from their tips and this has gradually increased towards the bottom of the leaf, then it’s a pretty clear indication of a potassium deficiency.
The leaf’s edges and tips may also appear to be burned.
Because potassium is critical in regulating the temperature of the plant, the leaves may struggle to regulate their temperature properly, resulting in a scorched, burned appearance.
Many people get confused between various nutrient and potassium deficiencies. However, instead of the entire leaf appearing burned, a potassium deficiency will only see the tips change color.
Moreover, the edges will also start to burn and, in only a short amount of time, a small hint of yellow will start to form.
Whether your plant’s leaves turn yellow or appear burned first can vary from one plant to another. If the leaves continue to lose their pigmentation and burn, however, they will eventually wrinkle up and die.
Dark spots of dead tissue can also form on the leaves, too. If you find any brown, red, or gray spots on the plant’s stem, this could also be a sign of potassium deficiency.
With some cannabis plants, the symptoms outlined above can be seen on their upper leaves. Because potassium moves around the plant freely, the deficiency may rear its ugly head in the upper leaves at some point.
A startling sign that the deficiency has become serious is when the plant’s growth has slowed down. This curd when the new shoots find it difficult to grow as quickly as usual, so their leaves are not as large compared to the older ones.
The main signs to look for are:
- A slower growth cycle
- Older leaves start to turn into a strong yellow color
- The leaf tips look “burned”
- The leaf tips start to die
- The edges of the leaves appear “burned”
- The plant grows too tall (stretching)
- The bud sizes and density start to decrease
- Although not as common, brown, red, or gray spots may appear on the plant’s stem
Why Is Potassium Important In Cannabis Plants?
Potassium is a key component in the flowering stage of a cannabis plant. It helps water move freely throughout the plant’s roots, stem, and leaves, as well as carbohydrates and nutrients in the plant’s tissue.
Potassium plays an important part in the production of starch, protein, and triphosphate (ATP). ATP is critical in regulating the rate of photosynthesis.
For a cannabis plant to develop and grow strongly, potassium is needed. It helps the stem develop, and improves the plant’s resistance to different diseases and cold temperatures.
Not only that, but potassium helps to regulate respiration and temperature to maintain healthy growth.
If the plant starts to experience a potassium deficiency, it can lead to many severe consequences.
First off, the plant’s growth may start to slow down, the production and number of buds will decrease, and buds that do grow may be too skinny to use, even after maturing.
There is no doubt that without potassium, plants, such as cannabis, will not survive.
Here are some of the amazing reasons why potassium is so important to a marijuana plant:
- It can increase root growth and even resist drought conditions.
- Helps with photosynthesis
- It reduces water loss and waiting
- It maintains turgor (the rigidity of cells or tissues)
- Improves translocation of starch and sugars
- Helps to reduce respiration so less energy is lost
- Helps fight off diseases
- Aids in overall protein content
- Can reduce lodging and helps to form cellulose
How Potassium Deficiency Affects Cannabis Buds
If a cannabis plant has a potassium deficiency, its bud formation may become delayed. Its bud size, density, and weight can be greatly affected, rendering the plant useless if left untreated.
Phosphorus is another crucial nutrient in the flowering stage of cannabis and without enough potassium, the plant could start to wither and eventually die.
Commercial fertilizers for flora tend to be packed with both phosphorus and potassium so are great options to use.
Why Your Plant Has A Potassium Deficiency
There are numerous reasons why your cannabis plant may have a potassium deficiency. The number one most common cause is a lack of potassium in the growing medium.
You should always ensure your plant is full of nutrients, especially during its growing phase. If you can see any signs of a nutrient deficiency, it probably means it requires more food, especially when flowering.
However, this doesn’t always mean cannabis needs more potassium. More often than not, it is given enough potassium and there are other reasons it is not absorbing the element as it should be.
A Variation In pH levels
One reason why your plant may be suffering from a potassium deficiency is that the pH level may be wrong. The pH variation of the substrate or the irrigation water may be outside the required range.
Therefore, the roots may struggle to absorb enough potassium, if there is a good amount of potassium present.
If the plant is grown in soil, the pH should be 6.0 to 7.0. For hydro and soil less growing, the pH should be 5.5 to 6.5.
Too Much Stress
Plants can experience stress and this can affect their development in many ways. Stress in plants is usually caused by poor pruning and/or too much heat. This, in turn, can cause a potassium deficiency.
If stress is found to be the cause, the plant should be able to recover within a few days, as long as you take care of it correctly and do not over- or under-feed it.
Light burn marks can appear and form spots, like potassium deficiency does. If your cannabis is grown indoors, the sunlight could be too close or too powerful for the plant to thrive properly.
Yes, your plants can withstand a lot of sun, but there is always a limit.
Too Much Salt
In some cases, the build-up of salt in the roots of a marijuana plant can impede its absorption of potassium. When this happens, you will need to fish the root system using clean water.
If you use hydroponics to grow your weed, this is not likely to happen, but it can occur. Therefore, always ensure you have a top-quality pump.
How To Solve A Potassium Deficiency
If your substrate is already being fertilized sufficiently, the symptoms outlined above should not be present.
If there is a lack of potassium in your cannabis plant, however, you must find the reason for it before trying to solve the issue.
As stated above, there are numerous possible reasons for a potassium deficiency, even when there are enough nutrients present.
The most likely scenario is that you’re not giving your plants enough fertilizer. Here are some tips on fighting this problem.
Make Banana Peel Tea At Home
One option is to make homemade fertilizer. This can help with nutrient deficiencies and even help buds develop properly during their flowering stage.
The peel of a banana is home to a lot of phosphorus and potassium, two important nutrients in flowering. Moreover, the banana itself contains these two nutrients when it becomes ripe.
By leaving banana peel to soak in water for a few days, bacteria will begin to form, and its nutrients will be absorbed by the plant.
Although banana tea is usually boiled, we don’t recommend this as you will lose some of the nutrients die to the high temperatures.
To make banana peel tea, follow these instructions:
- Allow the water to sit for at least a day.
- Cut your banana peels into different pieces.
- Place the banana peel pieces into a jar (up to around 5 cm)
- Fill up to 3/4 of the jar with water.
- Cover the jar with a rug, cloth, or towel.
- Leave it to sit in the refrigerator for three to five days.
- Stir a few times a day before using on your plant.
Using a flowering fertilizer is perhaps the safest and simplest method to solving an issue like potassium deficiency in cannabis.
Flowering fertilizer is available online, in nurseries, and your local grow shops.
Like all plants, cannabis requires multiple nutrients to bloom and thrive. With the right fertilizer, you can help it develop and become strong. But, you must choose the correct type of fertilizer.
In flowering fertilizer, you need to make sure it contains potassium (K) and Phosphorous (P).
You will find that the amount of potassium, phosphorus, and nitrogen is specified in such fertilizers, but bear in mind that nitrogen is not as necessary for flowering.
Altogether, there are two types of fertilizers available:
Organic fertilizers are absorbed more slowly but are incredibly beneficial for the soil and substrate. Chemical fertilizers will go directly to the plant’s roots and tend to be more precise.
When buying chemical fertilizer, you need to make sure that it is suitable and safe to use with edible plants.
The amount of potassium your plant requires depends on whether you are already adding supplements to it, as well as the brand you are using.
When buying fertilizer, read the instructions and label carefully to ensure it is suitable for cannabis plants. Do your research. Check online for comments from customers.
There are usually forums where you can ask for assistance, too.
- Use Tiger Bloom at the first sign of flowering
- To extend flowering or fruiting; add Big Bloom liquid fertilizer late in the season
- Formulated with a low pH to maintain stability in storage and keep micronutrients available
If nothing else works, you can try adding bone meal to your marijuana plant. This can be bought at any nursery, garden center, or online.
To apply to your plants, sprinkle some on the soil during the first few weeks of the flowering stage.
Bone meal fertilizer absorbs slowly. Therefore, cannabis plants will still continue absorbing it even after they have recovered.
Bone meal provides a great deal of potassium, phosphorus, magnesium, and calcium. So, if your plant is lacking in any or all of these, bone meal could be the answer.
It should ideally be used when preparing the substrate, ensuring that it is present throughout this entire process.
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Another method to try is to sprinkle some wood ash on the soil, as you would with bone meal. However, wood ash should only be an option if you grow your plants on the ground outdoors.
For those in pots, another method should be used.
Wood ash, as long as it is not wet, can provide a good amount of potassium to your plants. If it is wet, though, lime and salt may start to form in large quantities.
This can burn the roots or alter the pH levels, creating further nutrient deficiencies.
Start by using a small amount of ash and then see how the plant reacts. If the plant is okay, you can gradually increase the dosage.
Sprinkle it around the plant but above the ground (but do not cover all the soil). Just make sure the ash does not come into contact with the flowers or leaves.
If you decide to use wood ash, start regulating the soil pH to ensure it is at the right level for healthy growth.
Potassium deficiency is a common but potentially catastrophic problem with cannabis plants. The key is to spot the symptoms early enough to then tackle head on with our various methods above.
I’m an avid gardener and cannabis enthusiast. You can usually find me in my garden caring for my plants or at my computer crafting helpful blogs for my readers.