Matt Jonas is a small nursery owner in Sonora, California, and a home & garden
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Lawn mowing is considered one of the essential garden care and landscaping activities. It gives your lawn a more organized look and grass clippings on the ground help the soil retain more moisture, acting as a biodegradable mulch material.
The bad news is, you could be hurting bees and other pollinators and drive their colonies away.
According to research done by Susannah B. Lerman from the US Department of Agriculture, the frequency in which you mow your lawn affects bee abundance and diversity in suburban areas in a significant way.
The scientists wanted to know how different lawn mowing intervals affect pollinators in rural areas. Research Ecologist Susannah B. Lerman and her team studied 16 lawns in western Massachusetts which were mowed either weekly, bi-weekly or tri-weekly. Then they counted the species and number of wild bees that visited these test areas. They ensured that none of the gardens were sprayed with pesticides to kill weeds.
As expected, the grass that was cut every week was the least habitable of places while the lawns that were mown every three weeks hosted the most diverse communities of flowers and pollinator species.
Less mowing, more bees
Many species of wild bees, like other insects, have been declining in numbers in recent years. In addition to intensified agriculture and light pollution, disappearing food sources in gardens are considered a potential cause. Gardeners should, therefore, perhaps think twice before using high noise pollution gas lawn mowers with blades very close to the ground. Instead, use mowers that are powered electrically or by batteries to avoid driving insect colonies away. It’s also important not to cut the grass too short and remove grass clippings immediately. This gives ostensibly “weedy” flower species such as dandelions and clover to grow a bit longer and attract more bees. This guide has a nice filter feature for comparing mowers by their noise levels and blade heights.
The wild bee expert Paul Westrich goes one step further: he recommends mowing the lawn only two to four times a year. The best way to get through the high grass is with a beam mower, he recommends.
The best time to mow is at the end of May/beginning of June and September. Only then can a specific diversity of species develop and stick around: in addition to daisies, dandelions, and clover, there is also chamois speedwell, the little brown plum, ribwort plantain, buttercup, and the ground ivy. All these wildflowers are valuable to many bee species.