October Lawn Care Practices

Fall is considered optimum timing for many lawn care practices. Now that we’re into October, you may be wondering what you can still do, what should have been done back in September, and whether it is too late for some practices.

Cool season grasses found in Wisconsin lawns actively grow throughout fall, both via above-ground shoots and below-ground roots. This process is triggered by cooler weather arriving in early September and continues into October, gradually slowing down as temperatures consistently drop, finally leading to dormancy with the onset of winter. Timing of appropriate lawn care practices coincides with these changing growing conditions.

Overseeding existing lawns or seeding new lawns is the most time-sensitive. Ideally seed is placed into warm soil in late August or early September, leading to quick germination and establishment of seedlings. However, one key timing factor is enough time, usually about four to six weeks, for development before hard freezes set in. Thus, one very risky practice now is overseeding, better to delay until next season.

Another key practice for early fall, ideally early September, is nitrogen fertilization. Now that we are in October the risk becomes stimulating excessive grass growth, resulting in a lush lawn as winter begins. This creates favorable conditions for winter problems; most notably snow mold disease development. For low and most medium maintenance lawns, avoid fertilizing in October. High maintenance lawns could receive an early October nitrogen application.

Core aerating can still be done on lawns throughout October. Core aerating is a beneficial process for many lawns, in particular lawns that were established via sodding. Many soil issues, including compaction, limited topsoil over underlying clay, and poor surface drainage are improved by aerating. These same soil issues also lead to thatch problems, which core aerating will also help solve. Lawn grasses will respond with improved root growth this fall.          

Many rental agencies have core aerators, or services are available for hire. Core aerators will pull up small cores and drop them onto the surface; this is better than aerating machines that just punch holes in the ground. Lawns can also be topdressed with a thin layer of quality topsoil or compost in conjunction with aerating. The key to success when aerating is to make sure there is adequate soil moisture when the process is done. Finally, October is good timing for broadleaf weed control via herbicides. Make sure weeds are still actively growing. Read, understand, and follow all label directions. Liquid applied materials, sprayed directly on target weeds, work better than granular. Reduce the amount of herbicide applied by just spraying visible weeds, not lawn areas without any weeds.