Lawn winterization is not a one-size-fits-all operation. Two variables that will have the greatest influence on your winterization process are your location and grass type. The combination of location and grass type helps determine the “when and how” for lawn winterization. There are generalities that exist for winterization regardless of location or grass type. Below is a general overview of items to check off your list when winterizing your lawn. For a more nuanced discussion of each item, continue scrolling past this list.
- Adjust your mowing height before your grass stops growing
- Raise or lower mowing height (See discussion below)
- Final fertilization applications
- Nitrogen and potassium for cool-season lawns
- Potassium for warm-season lawns
- Put out your winter annual preemergence control
- Prior to soil temps dropping to 70 ℉
- Winterize mowers
- Clean off dead grass
- Drain oil
- Run gas out or add fuel stabilizer
- Remove battery
- Drain and prepare irrigation systems for freezing temperatures
- Blow out in-ground irrigation systems prior to hard freezes
- Drain and roll up garden hoses
- Drain and put away lawn sprinklers
- If necessary in your area, cover water spigots
Adjust your Mowing Height
Cool-season lawns can be an enigma when it comes to adjusting mowing heights in the fall. You’ll often hear two arguments. Some will say to mow low and drop the mowing height going into the winter. It is supposed to reduce snow mold occurrence and allow for easier emergence of new shoots in the spring. Others suggest just leaving the mowing height alone and letting the lawn remain the same height at which you were mowing in the late summer. This would allow the grass to maximize its photosynthetic capacity throughout the fall, but could also increase disease occurrence. There doesn’t really seem to be any research pointing to a best management practice or a consensus when it comes to mowing height adjustment of cool-season grasses in the fall. Maybe go with a trial-and-error method. Try leaving it alone one year, and lowering the mowing height another year. See what works best for you in your specific situation.
Raise the mowing height of warm-season grasses going into the winter. Of course, this needs to begin prior to the lawn going dormant. Maybe around the beginning of September, raise your mower up about 0.5” from where you were mowing during the season. This will help maximize photosynthesis during the fall by increasing the leaf surface area. Raising the mowing height can also help protect the plant from winter injury. The taller canopy can also help block sunlight from reaching freshly germinated weed seeds and any trying to germinate in the spring prior to lawn green-up; at the very least it could help slow their growth.
Whatever you decide to do with your mowing height, make sure to avoid scalping your grass down and weakening it going into winter. Regardless of grass type, continue to mow until your grass stops growing. If you continue to mow and you’re not getting any clippings for a few mows, late in the fall, that is the signal to put the mower up for the year.
Cool-season grasses in late September through early November are ready to continue their vigorous growth after suffering through months of extreme heat. This is a great time to fertilize cool-season lawns to help increase carbohydrate storage in preparation for winter. At the same time, warm-season lawns are getting ready to shut down for the season, but this doesn’t mean you don’t need to fertilize them. We can still continue to accumulate carbohydrates in the fall to help warm-season lawns make it through the winter.
Both cool- and warm-season lawns can be fertilized with a winterizer fertilizer but the product analyses and timing should be different. Warm-season lawns will require much less nitrogen at this point in the season compared to cool-season grasses. When using a winterizer fertilizer for warm-season lawns, it’s better to find one with a 1:1 or a low N:K ratio. Cool-season lawns can be fertilized with higher N:K ratio winterizers, like one with a 2:1 N:K ratio, because they will be able to utilize the increased nitrogen throughout the fall better than warm-season grasses. The fall is a great time to use a slow-release source of nitrogen, this will slowly become available throughout the fall, with its release controlled by temperature, which can match the temperature-dependent fertilizer demand of grasses. Avoid fall nitrogen fertilization of warm-season lawns after Oct. 1, unless you live in the extreme deep south and your grass stays green year-round.
Winter Annual Preemergence Control
The classification of annual bluegrass is up for debate (it may have perennial growth habits) but other weeds that seem to just appear overnight in the spring are actually winter annual weeds that germinate primarily in the fall, but also throughout the winter and early spring. These weeds flower and set seed in the spring and then die, only to complete this cycle all over again next fall. Controlling spring weeds begins in the early fall of the previous season. A well-timed preemergence herbicide (PRE) application will do an awesome job of controlling common weeds seen throughout the spring, like annual bluegrass, henbit, and purple deadnettle.
Disrupting the winter-annual-weed cycle is best done with applications of PREs in the fall, prior to or around the time of, the soil temperature dropping back down to 70 ℉. With PREs, if you’re too late, their efficacy is drastically reduced. Some PREs have residual control of small, freshly germinated plants, but most will need to be absorbed by the seedling right at germination to work properly. This means we need to have them in the soil prior to the temperature dropping to 70 ℉. If you’re worried about missing your window of control, you can try taking a full label rate application and splitting the rate into two separate applications about 2-3 weeks apart.
If all you’re dealing with is a hose and sprinkler setup, lucky you. Drain your hoses and sprinklers of any water that may freeze and crack plastic components or couplings during the winter. If necessary in your area, buy some hose spigot covers to protect your pipes from cold weather.
If you’re dealing with an in-ground irrigation system, make sure to blow out your irrigation system prior to the onset of winter. You might be alright for an early freeze or frost, but by the time mid-November rolls around, you’ll want to make sure everything has been winterized. If you’re not sure how to handle this yourself, it’s probably best to leave this to the pros. Hire a landscape company to come and use a large air compressor to properly blow out any water left in the pipes or heads, so it doesn’t freeze and crack anything important.
If you have a battery powered mower, the process for winterization is pretty straightforward. Two main things to take care of. Number one, clean the mower deck and blade of all dried, dead grass. Number two, drain or charge your batteries to a level of 70-80% capacity for long-term winter storage, this a good practice to increase the lifespan of your expensive batteries. You can either sharpen your blades now or in the spring, but checking the blade sharpness prior to mowing again is a good idea. If necessary, replace the blade or sharpen it to ensure a high quality-of-cut, essential for healthy grass. There may also be other manufacturer specific items to take care of and address prior to storing for winter, so check your owner’s manual, as well.
Gasoline-powered mowers have just a few extra steps necessary for proper winterization. Instead of battery management, we need to focus on oil and fuel. If your mower requires oil changes, now would be a good time to drain the oil for the winter and then fill it up with clean, mower-specific oil in the spring. Make sure you leave a note or something for you to remember that your oil is drained prior to starting the mower in the spring. Running your mower without oil could cause some serious and expensive damage. If your mower only requires topping the oil off when necessary, leave the oil maintenance until spring, when you’ll top the mower off with fresh oil prior to laying down your first cut. For your fuel tank, you can drain it of gasoline and run your mower dry prior to putting it up for winter or you can add some fuel stabilizer to your tank to keep your gasoline from becoming watered down over the winter. Make sure to check your air filters and clean or replace them, either now or in the spring. The more you do now, the less you’ll need to do when the warmer weather comes back around.
Making sure to address each of these specific areas will help you properly winterize your lawn, essential for healthy grass come spring. For any fall fertilization needs, contact us today or fill out our questionnaire for a custom lawn plan tailored to your specific situation.