Why the answer changes with the season
The Central Coast runs warm, humid summers and mild winters, and almost every home lawn here is a warm-season grass — buffalo, couch or kikuyu. Those grasses do the bulk of their growing between about September and April, then slow right down.
That is why a fixed schedule does not work. A fortnightly cut that keeps a lawn immaculate in June will have it looking shaggy by the second week of November.
A season-by-season guide
- Spring — weekly. Growth takes off, and this is when lawns get away from people fastest. Warm, wet weeks can mean twice a fortnight is not enough.
- Summer — every five to ten days. Kikuyu is the fastest of the three and often wants a weekly cut. After a run of storms, expect it sooner.
- Autumn — every two to four weeks, and start raising the cut height as the days shorten.
- Winter — every three to six weeks, or simply when it needs it. Some lawns want nothing more than an edge tidy for a couple of months.
The rule that beats the calendar
Rather than counting days, look at the grass. The one-third rule says never remove more than a third of the leaf in a single cut. So mow once the lawn has grown by about a third above the height you like it at.
Follow that and the lawn stays green after every cut, the clippings are fine enough to leave on the ground, and the roots keep pushing down instead of sitting shallow.
What happens if you leave it too long
Letting it run and then cutting it hard back is the single most common way people damage their own lawn. Taking off half or more of the leaf in one pass leaves yellow stalk with no green on it, shocks the roots, and opens the canopy up so weed seed gets the light it needs.
It also makes a mess. Long grass produces clumps of clippings heavy enough to smother the lawn underneath, so it all has to be caught or raked off.
What most people end up doing
Most of the yards Shane looks after sit on a fortnightly or monthly round, with the interval set to suit the lawn rather than the diary. Kikuyu in full sun gets seen more often than buffalo in shade. The point of a regular round is that the grass never gets away in the first place.