September 11, 2025, 7:43 am | Read time: 3 minutes
Meteorologically, fall begins on September 1. During this time of year, the weather is still very changeable and unstable. myHOMEBOOK consulted an expert to explain what lawn care is needed in September.
Aerating
September is a good time to aerate the lawn, explains Dr. Nonn from the German Lawn Society, provided it hasn’t already been done in the spring. “In September, there is still enough time for the gaps that inevitably occur after aerating to close up before winter,” the expert explains. Ideally, the lawn should be as dense as possible before winter. Otherwise, there is a risk that other plants will settle during this time when the grasses are less competitive, which would have to be laboriously removed in the spring.
More on this: How to Get Rid of Lawn Thatch Long-Term
Seeding
September is a good month for overseeding—especially if you have aerated beforehand, explains Dr. Nonn: “We have relatively warm soil, and if it rains naturally, all the better. Then there are ideal germination conditions, and by the end of October, a really nice and dense lawn will have developed again.” There are special lawn mixtures that can be used for overseeding in September. By the way, a good overview of which mixtures are suitable can be found at the German Lawn Society.
Fertilizing
Fertilizing is not strictly necessary, the expert explains. It is important to carefully examine the lawn and then decide. “If it is nice and green, then I don’t need to do anything regarding nutrient supply for now. But if it starts to show signs of hunger, I would fertilize again to ensure it grows dense, stays dense, or becomes denser.”
However, the expert recommends using a special fertilizer at this time of year: “I would go for a potassium-based fertilizer, a fall fertilizer in September, to further strengthen the grasses.” The expert advises against nitrogen-rich fertilizers for the lawn in September. Using this fertilizer would support height growth, which is no longer relevant in the fall.
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Mowing
In September, the weather is rather unstable. Some places have a lot of sunshine, while others have quite a bit of rain. Therefore, the lawn never grows uniformly everywhere. Dr. Nonn recommends observing the lawn and only mowing when growth is visible and mowing is necessary.
Avoid Moisture on the Lawn and Prevent Fungal Diseases
In September, the days are usually still warm, but the nights are already cool. This causes dew to form on the lawn. These conditions are ideal for the development of fungal diseases, explains Dr. Nonn. “If you see dew on the lawn in the morning, you should sweep or brush it off. I do this with a broom. If there are two of you, you can simply lay a hose down and drag it across the lawn.”