Potassium, Potash, K.
These three names all have to do with the same thing, and that's potassium. The word is derived from Potash, which is the mined salts that contain potassium.
The 'K' comes from kalium, the medieval Latin word for Potash, and can possibly be traced back to the arabic word qali, meaning alkali. In other words, potassium has a long history with humans, and with agriculture.
What is potassium?
Potassium is a soft, silver-white metal that in its pure form reacts violently with air and water. Besides manure, potassium is the potentially the earliest known "manufactured" soil amendment.
The "slash and burn" practice is done because the ash from burned fauna is rich in potassium, which mixes with the soil for more ideal growing conditions. It can also be mined from salts and used as an amendment, or even as part of the salt on your kitchen table.
With the introduction of inorganic fertilizers, potassium became a much more popular option for growers.
What does potassium do?
Potassium plays several roles in the health and growth of your plants, including stimulating early growth, promoting disease resistance, and improving the efficiency of water use.
With a healthy amount of potassium in your plants' cell walls, they can better deflect pathogens, reducing the plant’s susceptibility to powdery mildew and similar infections. Potassium helps your plants move nutrients throughout more efficiently, resulting in strong stems and perky leaves when you have the right amount of potassium.
While a lot of soil is naturally rich in potassium, it isn't always available to your plants. This means that your plant will have to fight harder to have access to potassium unless you make it easier for the plant to get to it.
In regards to the growth cycle, potassium is just as essential as nitrogen or phosphorus. Shocking, we know!
However compared to nitrogen which is most essential during the vegetative stage, potassium is most important during the flower stage. Failure to ensure your plants' access to potassium throughout its growth cycle, and especially during its flower stage can result in a potassium deficiency.
What is potassium deficiency?
When your plants are low on potassium to the point that it is noticeable when you look at them, they are likely suffering from a deficiency. But as we have said in our other breakdowns, nitrogen, phosphorus and potassium all show very similar symptoms of deficiency.
In all cases, the leaves will begin to yellow and die off from the bottom of your plant upward. This is because your plant is pulling all available nutrients including potassium to the top of your plant where it is receiving more light and energy.
Not taking care of the problem in time can result in lighter, lower quality yields, and in serious cases of potassium deficiency, the death of your plants.
How to fix potassium deficiency
Since a potassium deficiency looks so similar to nitrogen or phosphorus deficiencies, it's not an easy one-stop fix to resolve the issue. First you need to make sure it is actually potassium that is deficient.
This can be done by giving your plants a small dose of supplemental NPK. In other words, giving your plants small doses of nitrogen, phosphorus and potassium supplements separately can reveal the problem.
If you notice nothing happens with nitrogen or phosphorus but your plant begins to perk back up when you give it potassium, then you know that is the deficiency and can take steps to fix it. Just continue with the suggested dose of potassium supplements to get your plants back to normal.
It all works together
The grand lesson of NPK should be obvious at this point. There's a reason that even when a nutrient contains 0 nitrogen, the value will still be on the label. Because the interactions of nitrogen, phosphorus and potassium are tied together, and each nutrient has an impact on the others.
When any of these essential nutrients are missing, your plants will suffer and the other nutrients won't be able to do their jobs efficiently. If nitrogen, phosphorus and potassium are provided to your plant as needed throughout its growth cycle, you will almost always have a quality final product.
Without the proper amounts of every nutrient, your plants won't grow to their fullest potential. And yes, that includes micro-nutrients as well.
But that's a story for another article!