Plant nutrients: what are they?

What are the plant nutrients?

Just like us, plants also have many nutrients they rely on in order to grow and thrive. Some of these nutrients are more important for leaf growth, some others are critical for fruit formation and general health of the plant. Plant nutrients are generally classified in two major groups: Macro and Micro nutrients.

As their name suggest, they represent nutrients the plant uses in larger quantities (macronutrients) and those they utilise in smaller amounts (micronutrients). Here’s a simple breakdown:

• Macro: Nitrogen (N), Phosphorous (P), Potassium (K), Sulphur (S), Calcium (Ca) and Magnesium (Mg).

• Micro: Boro (B), Chlorine (Cl), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Zinc (Zn).

You don’t have to remember all the micronutrients as they are often less of a problem for home gardeners, but knowing the Macro ones and their function can be handy. Particularly, knowing the famous N-P-K combination can be a game-changer when fertilising your garden.

Why it matters

It may seem like random science and overcomplicating your hobby, but knowing the role of these nutrients can be useful when choosing what and when to fertilise. For example, knowing that nitrogen is responsible for leaf and biomass growth can come in handy if you are growing lettuce, rocket, coriander and other leafy greens. Similarly, knowing that potassium and phosphorous play a critical role in bud formation and blooming can help you choose a fertiliser richer in P and K, instead of heavy in N when your tomatoes flower!

Here’s a quick summary of their role.

• Nitrogen (N): very important during photosynthesis, this nutrient helps with leaf growth

• Phosphorus (P): important during flower and fruit formation, as well as root development.

• Potassium (K): also important for fruit formation, lack of potassium might be the reason your fruits are not pulpy or lack in flavour. This nutrient is also important for the lengthening of stems.

Of course knowing the other nutrients is very important, specially that Magnesium is often the cause of sad citrus plants (we’ll investigate this on a later post). But it’s also important to remember that to run a garden you don’t have to do things perfectly and there is no need to overwhelm yourself.

In fact, if you create a mini-ecosystem, instead of a perfectly curated garden, you’ll often find that you won’t need to worry about many of these things.

Fertilising: Golden Rule

If you ever find yourself in need of fertilising your plants, it might be helpful to remember the following rule:

• If you are growing salads or want your plants to grow in size and become bushier: Nitrogen

• Plants started to flower : Phosphorus and Potassium rich fertiliser (i.e tomato food)

Of course, it is important to check if your plants truly need to be fertilised or if the slow growth or sad appearance is coming from other factors like the environment or poor set up. But I do hope this guide helps you understand more of the plant world.

Happy gardening.