01/08/2026
Leave The Leaves & When Not To Leave Them
Dropped leaves are an important source of phosphate and nitrogen for ecosystems as well as important insect habitat. The new mantra amongst sustainable landscape practices has been “leave the leaves,” but it’s not always so simple.
Below is a picture of marsh grasses planted along a shoreline in the NNK. This shoreline is like many here mostly turf grass up to the water. The sparseness of trees, short grass, and proximity to water means that large amounts of leaves can easily make their way into creeks and rivers. This in turn adds to the nitrogen and phosphate in the Bay.
Agriculture and industrial runoff are far bigger culprits of phosphate and nitrogen runoff, but every source matters when our creeks and rivers are bereft of their natural defenses.
In cities and urbanized suburbs, leaves accumulate in the curbs and streets and enter the stormwater management system which often overflows to the Bay or, if not a combined storm sewer system, the leaves can cause backups and localized flooding.
This is not to say that leaving the leaves is bad! In fact, it’s a reminder to look at the entire system of your yard and look for imbalances. This property has large mature oaks with tons of leaves. The wetland grasses act as a buffer, but an even better buffer would be shoreline and near-shore grasses to collect leaf litter and runoff. Both are in the works here. In a city or urbanized suburb, residents can remove curbside leaf debris and repurpose it somewhere else.
Alternatively, for larger lot owners, we encourage creating a “rewilding area” where leaves, sticks, tall native grasses and shrubs can proliferate. It’s often easier to have one ‘crazy zone’ off to the side somewhere than trying to integrate wilder habitats in more manicured neighborhoods.