Read the NPK label
The three headline numbers show the percentage by weight of nitrogen, phosphate and potash. Nitrogen drives leafy growth and colour. Phosphate supports roots but is often already adequate in established soil. Potash supports stress and disease tolerance. The analysis matters more than the marketing name.
- Spring/summer feeds usually contain more nitrogen
- Autumn feeds use less nitrogen and relatively more potassium
- Iron can darken turf and suppress moss, but it is not a complete feed
- Slow-release nitrogen feeds steadily and reduces growth surges
Apply accurately
Measure the lawn rather than guessing. Multiply length by width for simple rectangles and split irregular lawns into sections. Calibrate a spreader on a small known area. Apply granules to dry foliage, then water them in if the label requires it.
- Never exceed the labelled rate
- Use two half-rate passes at right angles for even coverage
- Brush spills off paving immediately
- Keep products in original packaging away from children and pets
A sensible annual approach
A typical lawn may need a measured spring feed when active growth starts, an optional lighter summer feed only if moisture is available, and a low-nitrogen autumn feed. A soil test every few years is more useful than habitually adding phosphorus.
- Do not feed drought-stressed or frozen grass
- Delay feeding newly germinated grass until it has been cut several times unless the seed-bed product says otherwise
- Leave unfed areas under observation before escalating treatment