Mowing for Your Wildlife

What is the optimal mowing regime to support wildlife, combat climate change and still provide the benefits of a lawn?

Frequently mowed grass provides minimal habitat for wildlife. Flowering plants do not flower, biodiversity is quite low, organic soil material does not build up very much, and overwintering sites for insects are largely absent. Insects, and the birds and mammals that feed on them, require a continuous supply of native flowers and seeds from early spring through late fall for survival. Suitable nesting and overwintering sites must be available such as bare soil, rodent tunnels, and hollow stems of flowers and shrubs. Even mowing two or three times a season can substantially reduce available food and shelter.

Standard gas-powered lawn equipment emits relatively high levels of CO2 and other air pollutants. Lowering your carbon footprint and fossil fuel use through significantly reducing mowing, and better yet, eliminating fossil fuel use altogether, will help meet your zero emission goals. Further, increasing native plants on your property will make a meaningful contribution to helping wildlife manage the stresses of climate change.

How much lawn do you really use? Critically evaluate the amount of area you mow more than once a season and reduce your lawn to only what you actually use. Convert the areas you do not regularly use to field, meadow or woodland. Plant canopy trees. Tree canopy reduces soil carbon release and increases soil carbon storage by influencing soil temperature and moisture, and the presence of soil microbes.

When and how much should you mow? For lawns, the current best practice recommendation is every 2 or three weeks at most, starting in June. Emerging bees need flowers in your lawn in May. This regime allows some plants, such as clover, to flower. Also, leave grass clippings on your lawn to improve soil health and carbon storage. Many people are concerned about ticks. Recent studies have found that ticks are not commonly found on lawns mowed at this rate. Ticks require leaf litter and higher levels of humidity than are found on a mowed lawn. Host species like the white-footed mouse also need to be present. The highest levels of ticks were found in woodlands for these reasons.

For fields and meadows, the most wildlife-friendly mowing regime is a three-year cycle where only one third of the area is mowed each year either in late fall after all the flowers have bloomed and gone to seed, or in very early spring. This leaves sufficient overwin- tering habitat for a stable and a thriving wildlife population. It also allows wildflowers to compete effectively with grasses. If you have a field or meadow that you want to walk through, maintain a mowed path that is wide enough so that your clothes are not brushing against the plants. Do not use chemical pesticides. There is recent evidence that they are not only fatal to insects, but also soil organisms. Healthy soil microbes increase soil carbon sequestration. Avoid the use of herbicides.

Some invasives, such as Japanese Knotweed, are extraordinarily difficult to control manually, especially if they have been allowed to spread widely. Consult with invasive plant control specialists to make sure you use proper, safe techniques. Most small infestations of invasives can be adequately controlled with non-chemical means.

What to plant? When converting your lawn area to a flower or shrub border, a meadow or a woodland, choose exclusively native plants. The Norwich Conservation Commission website has resources to help choose plants indigenous to eastern Vermont as well as native plant nurseries. Continue to check the website as more resources will be added in the future. Consider starting plants from seed, but insist on pesticide-free seed, especially neonicotinoids. Even if the seeds are treated, the chemical turns up in the pollen and leaves, and kills bees. Try to select as diverse a group of plants as possible and one that will provide a succession of blooms from April to late October. One way to add diversity to a grassy field is to smother patches over one season and plant them with wildflowers the next year.