Autumn oversow: Is it worth it or a waste of time?

Whether you're establishing a new lawn or refreshing an existing one, autumn is the ideal season to oversow with cool-season grass.

Oversowing offers several benefits, but it’s also important to be aware of potential challenges.

 

One of the key benefits of overseeding is maintaining a lush, green lawn throughout the year. This approach, often called a "two-grass system," involves using one type of grass that thrives in the warmer months and another that flourishes during the cooler seasons.

Cool-season grasses typically germinate quickly, often within 7 to 14 days under ideal conditions. They also tend to be more shade-tolerant than warm-season varieties, making them particularly beneficial in winter when sunlight is lower and shaded areas are larger. While some sunlight is still necessary, these grasses can grow well with as little as 4 to 5 hours of daylight per day.

This two-grass system was once a standard practice on many elite sports fields. However, as more venues are transformed into multi-use facilities hosting concerts, monster truck events, rallies, and more, they no longer have a traditional "off-season." As a result, the time available to establish and re-establish grass for the next season has significantly decreased. Consequently, many of these venues now rely on cool-season grass, such as rye, year-round.

A local overseed/establishment in Melbourne, using Striker Fine - Tee, to hopefully combat the shade. 

From initial germination though to a nearly full cover within a week. 

Great job, Steph! 

There are also increased costs associated with this approach. These expenses include the cost of the seed itself, starter fertiliser, and potentially fungicides to support germination. If the cool-season grass is removed at the end of winter or early spring, additional costs may arise from the use of herbicides to aid the transition back to warm-season grass.

For those maintaining cool-season grass year-round, higher fertiliser costs are common, as these grasses typically require more nutrients. Additionally, water expenses tend to increase during the summer since cool-season grasses are far less drought-tolerant. Even when the cool-season grass is removed, the warm-season grass may experience a delayed "regreening" process due to being shaded out during the winter.

Overseeding is an integral part of our maintenance regime. Being a 100% perennial ryegrass field year-round, we need to be proactive in continually ensuring that we have new seedlings emerging at all times—whether it be in high-wear areas for AFL, such as goal squares or the centre corridor, new growth ready to germinate as soon as the floor comes up after a concert, or simply maintaining a healthy, dense grass cover. This is especially important heading into winter when growth and recovery slow significantly due to dropping soil temperatures and shorter days.

 

Overseeding warm-season grasses—you want to begin overseeing once the air and soil temperatures decrease.

Ideally under 25 degrees air temperature

 

The couchgrass should be thinned out using a scarifier and then a PGR applied.

Ryegrass should be applied using a dimple/disk or spike seeder at a rate of 2-4 kg/100 m2. If possible, apply a light sand topdress, and then once the seed cracks, apply a turf starter (like 2 Spec Establish) and then a fungicide to prevent Pythium (Impala).

Stay off with moving machinery for a week and then slowly begin to mow, mowing just the tips.

Once it is established, it can be mowed with a cylinder mower at your desired height (recommend between 24-32mm)

 

For the Addicts keeping up with our Warm Season free lawn plans we’re at that time again where we are doing our monthly soil amendments. So, the Hydrolink, Kelpro, and for those who use them, UMX, Fertech bio, Auxinone and Hicure.

 

For the Addicts keeping up with our Cool Season free lawn plans, we’re up to the big one! The basis of all our plans. Granular, Hydrolink, Kelpro, and for those who use them, UMX, Fertech bio, Auxinone and Hicure.