Spring, when growth is established, and again in early autumn — with two different products. Feeding a lawn with the wrong one at the wrong time is worse than not feeding it.
The two feeds
Spring and summer. Nitrogen-led. The job is leaf growth and colour, and the plant can use it because it is growing hard. Often sold with slow-release coating so the effect lasts weeks rather than a fortnight.
Autumn. Potassium-led, nitrogen low. The job is to harden the plant going into winter: stronger cell walls, better root development, more disease resistance. A nitrogen feed in autumn pushes soft green growth at exactly the point the lawn should be closing down, and that growth is what disease takes.
The bags say which is which on the front, and the figures on the back confirm it.
What the three figures mean
NPK: nitrogen, phosphorus, potassium, as percentages by mass. On a lawn product the useful reading is the ratio rather than the absolute numbers — high first figure and low third is a growth feed, low first and high third is an autumn one.
Phosphorus, the middle figure, is usually low on established lawn feeds and higher on products aimed at new sowing, where root establishment is the point.
The two rules that avoid scorch
Spread evenly. Concentrated granules burn, and the marks are stripes that last months. This is what a spreader is for, and why the setting matters more than the machine.
Water it in, unless rain is imminent. Granules sitting dry on leaf can scorch; dissolved and in the soil they cannot.
What this site does not tell you
What any specific product may be applied to, at what rate, or with what precautions. That is on the label, it is a legal document for a regulated product, and the pages here print the maker’s stated rate and point at the label rather than paraphrasing it.
How this site handles it
The fertiliser shelf prints the NPK as stated, the coverage in square metres per bag, and whether the product is described as slow-release. The spreader shelf is separate, and those pages state working width and whether a calibration setting exists.
Wherever this page and the maker’s own documentation disagree, the documentation wins. Every cutting width, cutting height, stated area, pack capacity, flow rate, head, sound level and application rate on this page comes from the maker’s own published figures, with the unit as printed and the source named. None of it is measured here, and no figure is converted into another convention, because a converted number is a different number. And the document this page hands back: the dose, the precautions and what a product may be applied to are on its label. That label is a legal text for a regulated product, and paraphrasing it would be rewriting it. This page reports the coverage and the analysis as the maker prints them, and points at the label for everything else.
The questions that keep coming in
What is the difference between a spring and an autumn feed?
The balance. A spring feed leads on nitrogen to drive leaf growth; an autumn one drops the nitrogen and leads on potassium, which hardens the plant for winter rather than pushing soft growth into it.
Can I use general garden fertiliser on a lawn?
It will do something, unevenly. Lawn feeds are formulated and sized for spreading over a surface at a low rate, and the granule size is part of that. What any product is approved for is on its own label.
Last reviewed 26 September 2026