Lawn care

Page last updated: Friday, 25 May 2018 - 10:30am

Fertilising

Only apply fertiliser when symptoms of nutrient deficiency occur like yellowing. On Perth sandy soils, an application of 25g/m2 of a complete fertiliser, containing 10-12% nitrogen (N), 1% or less phosphorus (P) and 6-10% potassium (K) is recommended in autumn and spring, when grass grows rapidly. Most commercial fertilisers contain all the essential elements. Lawns need less fertiliser if grass clippings are recycled during mowing by removing the catcher. Buffalo grass requires less fertiliser than couch. As pollution of waterways due to phosphorus leaching from gardens is an issue in Perth and in other parts of Western Australia, the use of a complete fertiliser without phosphorus is another environmentally responsible option for home gardeners. Because phosphorus leaches slowly, it may not need to be applied as frequently as N or K. Try alternating fertiliser with mixtures which do not contain P.

Mowing

Different cutting heights are recommended for different grass varieties. A lawn will become thin, weak and prone to disease attack and weed invasion if it is consistently cut too short. As a rule, you should never cut your grass lower than 2.5cm. Adjust your cutting according to the seasons: cut shorter during active growth and longer at the end of the season. Longer grass will use less water as more of the soil surface is shaded.

To maintain a lawn of reasonable quality, mow weekly in summer and reduce the frequency to monthly (or less) in winter.

In general, make sure that no more than 40% of the leaf area is removed in one cut. Avoid cutting the lawn when it is wet.

Most people remove the clippings from the lawn. However, this depletes it of valuable nutrients. If you decide to leave the clippings on the lawn, make sure that they are spread evenly and thinly. Thick layers of clippings produce heat and/or may harbour diseases, which could harm the lawn beneath. Leaving the clippings on the lawn may also lead to a faster build-up of the thatch layer.

Mulching mowers are now commercially available. They shred the grass to a fine layer which breaks down faster. This is a more effective way of recycling the valuable nutrients.