Lawns

A lawn is the most demanding planting in most Australian gardens: it wants more water, more feeding and more of your time per square metre than anything else you could put there. That is a fair trade if the lawn is used. It is a poor one if it exists because the space had to be something and grass was the default.

Decide how much lawn you actually need

Before choosing a grass, work out which parts of the lawn are walked on, played on or sat on, and which parts are simply green. The used parts justify the maintenance. The rest — narrow strips beside the house, the shaded southern side, steep banks, the awkward triangle behind the shed — are usually better as garden bed, groundcover or paving, and each square metre converted is a square metre off the mowing and watering.

Two positions in particular are worth reconsidering. Deep shade under an established tree will never carry a decent lawn no matter which variety is used, because turf grasses need light and tree roots take the water first; that is a job for shade groundcovers or mulch. Slopes steeper than about 1 in 4 are difficult and unsafe to mow and better planted with clumping plants that bind the surface.

Warm-season and cool-season grasses

This is the fundamental choice and it is decided by climate, not by preference.

Warm-season grasses — couch, kikuyu, buffalo and zoysia types — grow through the warm months, spread by runners, and go dormant and straw-coloured through winter in cooler districts. They handle heat, wear and drought far better than cool-season grasses, and they recover from damage by running back into it. They dominate in tropical, subtropical, arid and warmer temperate districts, which is most of the country.

Cool-season grasses — fescue and ryegrass types — stay green through winter and grow in spring and autumn, but they struggle through hot dry summers and need considerably more water to get through January and February. They suit cool-zone gardens and shaded positions in cooler temperate districts. They grow from seed rather than spreading by runner, so wear damage has to be repaired by resowing.

Winter dormancy in a warm-season lawn is normal, not a failure. Watering and feeding a dormant lawn in July does not green it up; it simply wastes both. The grass will come back when soil temperature rises.

Establishing a new lawn

Preparation decides the outcome, and it is the step most often shortened. Remove existing vegetation, then cultivate the top 100 to 150 mm and break up any compacted layer beneath, because turf laid over a compacted pan will be shallow-rooted and thin for its whole life. Grade the area with a slight fall away from the house — even 1 in 100 is enough to move surface water — and rake out hollows, since low spots will hold water and thin out.

Add a layer of screened sandy loam if the existing surface is heavy clay, and roll or firm the surface lightly so it does not settle unevenly after the first watering. Lay turf with staggered joints, butted tightly, and water it heavily and immediately — a newly laid lawn cannot be over-watered in the first fortnight. From then on, taper towards deep infrequent watering.

Turf is quicker and more reliable; seed is cheaper and is the only option for cool-season lawns over large areas. Either way, autumn and spring are the establishment seasons. A lawn started in December in a hot district needs constant attention to survive its first month.

Mowing

Mowing height does more for a lawn's health than anything except watering. Grass cut short has less leaf area, produces less energy, grows shallower roots and dries out faster. Grass left slightly longer shades its own soil, keeps roots cooler and out-competes weed seedlings for light.

Raise the blade through summer, particularly during heat waves. In practice this means running one or two notches higher than you would in spring. In warm-season lawns, 25 to 40 mm suits couch and zoysia, while buffalo types prefer 30 to 50 mm. Cool-season lawns are generally happier at 40 to 60 mm.

Never remove more than about a third of the leaf height in one cut. Scalping a lawn that has got away from you does more damage than the long grass did; cut it twice a week apart instead, lowering gradually. Keep the blades sharp: a blunt blade tears the leaf and leaves a ragged brown tip across the whole lawn.

Leave the clippings on the lawn most of the time. They break down quickly, return organic matter and moisture to the soil, and do not cause thatch in normal use. Remove them only when the grass has got long and the clippings would lie in mats.

Watering a lawn

Deep and infrequent, as everywhere. One or two long waterings a week that wet the profile to 150 mm produce a deeply rooted lawn. Daily light sprinkling produces a shallow one that wilts the moment you stop.

Measure what your sprinklers deliver by placing a few straight-sided containers on the lawn and running the system for a set time. Most people find coverage is far less even than it appears, with dry arcs at the edge of throw that account for the patches that always look worst.

Water in the early morning. Check current restrictions with your local council or water authority before setting a schedule; they vary by authority and change with storage levels.

Feeding, aeration and top-dressing

Feed warm-season lawns as growth resumes in spring and again in early autumn, using a slow-release complete fertiliser. Feed cool-season lawns in autumn and early spring. Do not feed a dormant lawn. This site does not recommend brands or publish application rates; follow the directions on whatever product you use.

Aerate compacted areas — gateways, the line between the back door and the clothesline, wherever the ground is hardest — by pushing a garden fork in to full depth every 150 to 200 mm and levering gently. Do it when the soil is moist, in autumn or spring. Brushing a sandy top-dressing into the holes afterwards keeps them open.

Top-dress with a thin layer of screened sandy loam or compost, no more than 10 mm at a time, to level minor hollows. Anything thicker smothers the grass. Repeat over several seasons rather than trying to correct a bad level in one go.

Weeds and wear without sprays

This site does not cover herbicides or any other chemical control. In a lawn, the practical approach is competitive: a dense, well-fed lawn mown at the right height leaves very little bare soil for weed seed to germinate into, and thin patchy lawns are where weeds appear. Where individual weeds establish, remove them by hand with a narrow trowel or a weeding knife, taking the root, and do it while the soil is moist and before they set seed.

Repair worn patches by physically renovating them: fork the area to relieve compaction, top-dress, and either lay a patch of turf or over-sow, depending on the grass type. Where a path has worn through the lawn, the honest answer is that people will keep walking there — put a paved or gravel path in and stop fighting it.

Common lawn problems

Thin, yellowing grass under a tree. Light and root competition, not feeding. Reduce the lawn area and mulch or plant instead.

Patches that dry out first every summer. Usually uneven sprinkler coverage or a compacted layer beneath. Check both before adding water.

Water beading on the surface. Water-repellent soil, common in sandy lawns after a dry summer. Fork the surface and water in several short cycles rather than one long one.

A spongy layer above the soil. Thatch build-up, most common in vigorous runner grasses. Reduce by scarifying or vertical mowing in late spring when the lawn is growing strongly enough to recover.

Straw colour across the whole lawn in winter. Normal dormancy in a warm-season grass. Do nothing.