NPK Breakdown: Phosphorus

NPK Breakdown: Phosphorus

Every bottle of nutrients you see at Cultivate is going to have an NPK label.

These letters stand for Nitrogen (N), Phosphorus (P) and Potassium (K) and they are essential to the healthy development of your plants. If your plant is missing any of these elements, it will not survive.

Each element serves its purpose in plant development, from initial growth through the final stages of flowering. This makes nitrogen the most essential element during early growth, and phosphorus and potassium later on.

But really, all three work in unison throughout the entire growth process to produce a strong healthy plant. That's why it's important to know the importance of every single one!

What is Phosphorus?

Phosphorus is a chemical element with the atomic number 15. It’s highly reactive and is found in ATP, DNA, RNA, phospholipids, and the Earth’s crust. In other words, it can be found in all life!

Behind nitrogen, phosphorus is considered the second most essential nutrient because of its responsibility for managing biological functions like helping plants capture and store energy from the sun during photosynthesis. Phosphorus converts ADP (adenosine diphosphate) into ATP (adenosine triphosphate), a chemical found in all living things that stores and transfers energy.

ATP provides the energy to drive many different processes and biochemical reactions from seedling growth to harvest. Without phosphorus, there is no ATP.

Is That a Phosphorus Deficiency?

When your plant is young, a phosphorus deficiency can be hard to catch. A phosphorus deficiency will be shown through less growth during the early stages of vegetative growth.

Smaller leaves, stems, and shorter overall plants compared to others at the same stage of development is a good sign that your plant could be missing phosphorus. If a deficiency occurs in a later stage of growth, it can be easier to spot.

The early stages of phosphorus deficiency in more mature plants typically expresses itself through the leaves. They will turn a purplish-red hue, which should be noticeably different from the natural color of your plants.

If you can catch the deficiency here and stop it, then you can avoid a lot of trouble down the road. However if you don't notice it right away it can develop into a much more noticeable problem, turning from purplish-red to dark brown as your leaves start to die.

Fixing a Phosphorus Deficiency

The problem a lot of growers face with NPK deficiencies is that they can look pretty similar. This can bring in a little bit of guesswork on the part of the grower, which is always uncomfortable when you're dealing with your plants!

Because the deficiency could be phosphorus, or nitrogen, or potassium, it's best to test out just a couple plants instead of the whole garden. For example, if you have six plants, and all of them look they might have a phosphorus deficiency, give just two plants a phosphorus supplement to see if anything changes.

If you notice positive results, then you can incorporate the supplement into the rest of your plants. The reason we do this is in case the deficiency is from something other than phosphorus. If phosphorus turns out not to be the problem, giving all of your plants extra phosphorus can lead to nutrient lockout of other nutrients.

If you want to be sure which deficiency you have before you start giving it supplements, check out our article figuring out nutrient deficiencies.

Just the P in NPK

It's important to remember that even though phosphorus is essential to plant growth, it is only one part of the three-part NPK formula that your plants need. Nitrogen and potassium are just as essential as phosphorus and you should monitor how much of each your plant is receiving constantly.

Stay tuned for more breakdowns on nitrogen and potassium to get the full scope of how important these three elements truly are!

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.