By CroquetClaude · 1 min read
Understanding N-P-K
What the three numbers on a fertiliser bag actually mean, and what each one does for a croquet court.
The three numbers
Every fertiliser bag shows three numbers, always in the same order: nitrogen, phosphorus, potassium. A bag marked 15-5-10 is 15% nitrogen, 5% phosphorus, 10% potassium by weight. The rest is filler and other minor nutrients.
What each one does
Nitrogen (N) drives leaf growth, colour and density. It's the nutrient couch grass responds to most visibly, for better and worse: too much in summer produces a lush, soft flush that mows poorly and invites disease.
Phosphorus (P) supports root development. It matters most at establishment and after renovation. On a well-established court it needs far less attention than nitrogen.
Potassium (K), sometimes called the "toughening" nutrient, builds drought resistance, wear hardiness and disease resistance. It's the one worth banking before the stress of a QLD dry season, which is why it gets emphasis in the autumn (March) application.
Why the ratio changes through the year
A spring application leans on nitrogen to trigger recovery growth. An autumn application leans on potassium to build resilience before dormancy. That's why the same bag doesn't suit every month, and why a seasonal programme names a different product for each application rather than one all-purpose mix.