Forty per cent of the year's rain falls in January, February and March. A mowing schedule that ignores that is either wasting your money for half the year or losing your lawn for the other half.
The short version
- The Bureau of Meteorology has 93 years of record at Archerfield Airport. Mean annual rainfall is 1,061.1 mm.
- February (156.3 mm), January (134.6 mm) and March (133.8 mm) carry 424.7 mm between them, just over 40 per cent of the year in three months.
- September is the driest month at 34.6 mm, and the mean July overnight minimum is 7.8 degrees, so warm season grass all but stops.
- That means weekly to ten daily cuts through the wet, and three to four weekly through winter. One fixed interval all year is wrong twice.
- October is the turn: rain roughly doubles and the nights warm up. Get ahead of it then rather than catching up in January.
What the Archerfield record actually says
Mount Gravatt, Sunnybank and Carindale all sit within a few kilometres of one of the longest running weather stations in south east Queensland. At Archerfield Airport, station 040211 the Bureau of Meteorology has 93 years of rainfall on the books, from 1929 to now, and the mean annual total is 1,061.1 mm. the Brisbane station, 040913 a little further north reads 1,065.2 mm. Two different records, two different lengths, near enough the same number.
The annual total is not the useful part. Where it lands in the year is.
Two fifths of the year's rain in three months
At Archerfield the three wettest months are February at 156.3 mm, January at 134.6 mm and March at 133.8 mm. Add them together and you get 424.7 mm, which is just over 40 per cent of the entire annual average falling in a quarter of the year.
Then it shuts off. September averages 34.6 mm and August 35.6 mm. February brings more than four times what September does. The station also counts rain days, and the pattern holds there: 9.8 days of rain in February against 4.2 in September.
So a Brisbane lawn does not get a steady trickle it can grow along with. It gets a long dry stretch through late winter, then a wet quarter where the water arrives in volume.
Warmth is the other half, and it moves the same way
Rain on its own does not make grass grow. Warmth does, and the two peak together here.
The Archerfield record puts the mean overnight minimum at 20.5 degrees in January and 7.8 degrees in July, with a yearly mean of 14.5 degrees across 51 years. The mean 3pm temperature runs 28.8 degrees in January against 20.2 degrees in July.
Almost every lawn across Brisbane's southern suburbs is a warm season grass. Couch, buffalo, kikuyu and zoysia all behave the same way: they grow hard while the ground is warm and they slow right down as the nights cool. A July night at 7.8 degrees is not a growing night.
Put the two records side by side and the year splits cleanly. Hot and wet from December to March. Cool and dry from June to September. The lawn is doing something completely different in each half, and the mowing has to follow it.
What that means for how often you cut
Through the wet months a lawn here can put on a week's growth in four or five days. Fortnightly stops being enough somewhere around late December, and stays not enough until March. Weekly or ten daily is the honest interval through that stretch.
From about May the same lawn can go three or four weeks and look no worse for it. Cutting it weekly through July is not care, it is just noise and money.
This is why our lawn mowing runs are not one fixed number all year. A schedule that made sense in February is the wrong schedule in July, and the other way around.
The one third rule, and why the wet season breaks it
The standard rule for any lawn is to take no more than about a third of the leaf off in a single cut. Go harder than that and you expose stem and soil, the lawn browns off, and it takes weeks to knit back together.
In February that rule is easy to break by accident. Miss one cut in the wet and the grass is far enough ahead that bringing it back to a normal height means taking half of it or more. The fix is not a lower blade, it is two passes a few days apart.
This is the single most common reason a lawn in Carindale or Sunnybank looks scalped and yellow in midsummer. Not the mower. The gap before it.
What stretching it too far actually costs
A lawn left long through the wet does not simply need a bigger cut. Three separate things start happening.
The clippings stop disappearing
A short cut drops fine clippings that break down in days. A long cut drops rows of wet clippings that sit on the surface, block light and leave pale stripes across the lawn. On a summer cut that is usually the point where the clippings have to leave the property rather than stay on it, which is what our green waste removal is for.
Weeds get their window
Long grass falls over. Where it falls it opens gaps, and gaps in a warm wet February are exactly what broadleaf weeds and nutgrass are waiting for. A lawn kept at a consistent height through the wet crowds them out on its own, without anything being sprayed on it.
The edges go first
Edges and garden borders run away faster than the open lawn because they get water off the hard surface next to them. A fortnight in February is usually enough for the edge to lose its line completely, which is the difference between a lawn that looks maintained and one that just looks cut. Keeping that line is part of garden maintenance, not an extra.
Height matters more than most people think
The other lever, and the one almost nobody touches, is how low the blade sits. Cut short and the lawn dries out faster, because there is less leaf shading the soil. Cut a little longer and the same lawn holds moisture through a hot week and shades out the weeds trying to get started underneath it.
Through the wet quarter that works in your favour, because the grass is growing fast enough to carry the extra length without looking shaggy between visits. Through winter it matters for a different reason: with the nights down near 7.8 degrees the lawn is barely replacing what you take off, so anything cut hard in July stays looking bare until October.
Buffalo in particular does not forgive a hard winter cut. It is the most common lawn across Brisbane's southern suburbs and it recovers from the runner, not the seed, so there is no quick fix once it has been taken back too far.
The bits that grow on a different clock
Lawn is not the only thing responding to that wet quarter. Hedges, shrubs and garden beds all push hardest through the same months, and they need a different interval again.
A hedge cut once in spring will be out of shape by February. Two lighter cuts across the growing season hold a much better line than one hard cut trying to undo six months of growth, and the plant stays denser for it. That is the same logic as the one third rule on the lawn, just on a slower clock. Our services page sets out how the two schedules fit together across a year.
Catch up costs more than keeping up
There is a money argument in here too, and it runs the opposite way to what people expect. A lawn cut on a tight interval through the wet is a fast, simple job every time. The same lawn left to run is a long job with bagging, a second pass and a trailer load of clippings to take away, and it looks worse for a fortnight afterwards while it recovers.
Across a full year the tighter summer schedule usually works out close to level, because the winter visits drop away to once a month. What changes is that the lawn never has a bad stretch, and you are not paying extra to fix something that did not need to happen.
When to start again in spring
September is the driest month on the Archerfield record and the nights are still cool, so the lawn is not away yet. October is the turn. Rainfall roughly doubles from 34.6 mm in September to 79.0 mm in October, and the overnight minimum climbs from 11.3 to 14.6 degrees.
That is the point to bring the interval back in, tidy the edges and get the hedges back into shape before everything is growing at once. Getting ahead of the wet in October is far less work than catching up in January.
A note on when we can actually run a mower
There are hours on this. Brisbane City Council sets the times for power tools and garden equipment, and the practical effect is that early starts and late finishes are not available even when a customer asks for them. It is worth knowing if you are trying to book around work hours, because it shapes what a run can cover in a day.
Where to start
If your lawn is on a fixed year round interval, it is being cut too often for half the year and not often enough for the other half. Moving to a schedule that tightens through the wet and relaxes through winter costs less across the year and the lawn looks better in the months anyone is actually outside looking at it.
We mow across Mount Gravatt, Upper Mount Gravatt, Carindale and Sunnybank, and we set the interval by the season rather than by the calendar. If you want it looked at, get in touch and we will tell you what your lawn actually needs through each part of the year.