Most Australians have been fertilising at the wrong times of the year. Australia’s relatively warm winter climate and our change in turf types has been highlighted in research as a reason why we should be fertilising in winter and less in spring and summer. This research conducted by Ozbreed has shown that it is possible to keep Buffalo, Kikuyu and Zoysia turf green all year round when following optimum fertiliser applications and certain mowing practices, even in frost prone areas. This research has designed recipes to keep these turf types green all year round in many parts of Australia, using specialised fertiliser formulations. Most Australian studies of winter fertilising warm season turf have been conducted on Couch turf, which in this study showed poor results. Most USA and other overseas research on winter fertilising has been conducted in regions that reach minus 10° Celsius or colder in winter, yet have warm temperatures for the rest of the year: regions such as Florida, Texas, and Georgia in the USA. In these regions winter fertilising can cause winter kill. In Australia, only climatic regions similar to Canberra and Armidale get that cold and have the potential for winter kill if fertilised in winter. For the rest like Melbourne, Sydney (Including frost affected Western Sydney where the research was conducted), Perth, Adelaide and Brisbane, this research unlocks the true potential of keeping lawns green in winter.
In brief, the research involved fertilising replicated plots of numerous turf types with many different timing combinations, using a specialized autumn and winter blend of slow and quick release fertiliser and iron. Earlier research highlighted that a product called 2 Spec Elevate from Globe, provided the best performance for winter colour compared to other fertilisers tested. Large areas around Ozbreed trial gardens were also tested, including shaded areas. Some areas were not fertilised at all, whilst others had either regular autumn fertiliser, or heavy autumn fertiliser. Parts of these areas then either got no fertiliser in winter, or a heavy fertiliser in winter.
The results were unexpected. Common practice is to not fertilise in winter, as it is seen as a waste of time, or is often considered to hurt a lawn. This research for regions that do not usually get colder than minus 3° Celsius clearly shows that winter fertiliser greatly improves the green colour of many turf types. Over 30 frosts were recorded with a lowest temperature of around minus 3°c. In general, Kikuyu, most Buffalo and Zoysia types benefited from autumn and winter fertilising. Couch however showed no real benefit from winter fertilising in this trial. As Couch is probably the most researched sports turf, it is little wonder that conventional research and practice say to not fertilise lawns in winter. If well fertilised in winter, the lawns needed no fertiliser in spring to quickly green. Those that did not have winter fertiliser and no spring fertiliser struggled to green up. Next autumn and winter try fertilising your client’s lawn at a heavy rate.
Based on this research different recipes have been formulated to keep Buffalo, kikuyu, and Zoysia green all year round for many Australian regions. If you have Couch, these recipes will generally not work.