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Shoots, Roots, Fruits – Understanding Fertilizer

Have you ever found yourself standing in front of a box of fertilizer at the garden centre trying to decipher numbers that don’t make sense to you?

20-20-20… 15-30-15… 3-3-2

What do these numbers mean?! What do I need!? There is a lot of meaning behind these numbers…. the science world is vast and wild! This post is intended to break down the basics, without adding confusion. Our goal is that you will understand the general sense of fertilizer and will feel more confident and won’t be left scratching your head in the middle of the garden store.

plant potting tools

What is plant fertilizer?

You may have heard people refer to fertilizer as “plant food” or “nutrients”, but in reality they are nutrients for the soil that help our plants grow. Without the help of our soil and fertilizers, we would not get the same results out of our plants. Plant fertilizer is a chemical or natural ingredient that is added to your plant’s soil to help with their growth. However, by using a natural fertilizer our plants are able to get a much more balanced diet from the soil. By using a synthetic or chemical fertilizer, you will not get the same results from your plants, as you would’ve if you used an organic fertilizer.

What are the main components of fertilizer?

So, the three numbers that stand for three chemical elements, and are often outlined as: N-P-K. They are ALWAYS in that order and will never switch around.

N = Nitrogen
P = Phosphorus
K = Potassium
These are the three primary nutrients that help support growth for a happy and healthy plant.

Shoots-Roots-Fruits!

Let’s break it down to make more sense, what element does what for the plant? Think about nitrogen having a separate job from phosphorus and so on.

So, when you see N-P-K, think “Shoots-Roots-Fruits.”

  1. Shoots = Nitrogen
  2. Roots = Phosphorus
  3. Fruits = Potassium

Now let’s dive one more step deeper:

  1. Shoots = Assists with foliage and vegetative growth (leaves and anything that grows above ground)
  2. Roots = Aids with healthy root growth (underground and what we don’t see)
  3. Fruits = Helps promote flowers and fruit (vegetable) formation and size
potting a plant

Is there such a thing as too much fertilizer?

Yes! There is such a thing as too much fertilizer. Excessive use of fertilizers can damage the plants and can decrease the soil’s fertility. For example, if your tomato plant is tall and green but is lacking in fruit production, there may be too much nitrogen in the soil. When you are picking a fertilizer, larger numbers don’t necessarily make for a better fertilizer. Listen to your plants and try to pick a fertilizer that is best for their needs.

How do I choose a fertilizer?

  • Test the pH levels of your soil. Finding soil testing kits is very easy, and can be found on Amazon. Say you are trying to test the soil of your lawn, the soil should have a pH of 5.5-7.0.
  • Get to know your plants and try to understand their needs. For instance, if you are planning on transplanting, you may want to pick a fertilizer that has a higher Phosphorus number (2-8-4).
  • If you are unsure you can always choose an all-purpose fertilizer (5-5-5). Meaning there is an equal amount of Nitrogen, Phosphorus and Potassium (Shoots, Roots and Fruits).
Pepper Seedlings
soil pH test

The next time you go into a store to purchase some fertilizer, just remember ‘Shoots, Roots and Fruits’, in that order! The fertilizer numbers on the bag are also in that order, so by remembering ‘Shoots, Roots and Fruits’, hopefully that will help you the next time you need to buy fertilizer.

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2 Comments

  1. Great tips for my plants , thankyou so much. I will let my friends know.

    • Thanks Miriam, happy to hear that!


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