In temperate climates like that of the Minneapolis-area, Fall is a beautiful, but also thoughtful time in the garden and the environment at large. It’s a time of harvest, but also a time of death, dormancy, and subsoil activity.
One of the mistakes many gardeners and landscapers make is in treating all of the Autumn deadfall as waste to be removed from the space, rather than as a resource. There are a number of ways in which designing with the decay of the season can improve soil fertility, and the health of plants for next year.
A natural part of the lifecycle of temperate-zone trees and shrubs is in dropping not only leaves, but twigs and branches that grew in an inopportune location for accessing solar resources. This deadfall can provide a basis on which soil-enriching fungi can grow their roots, called mycelia. Allowing sticks, branches and even logs to remain on top of your soil can help with soil carbon levels, water retention, biodiversity, and even create a warmer microclimate when decomposition picks up.
Using decaying organic matter on top of the soil forms a mulch, which is an organic layer that tops the slay, sand, and humus below, similar to what you would walk on top of in a forest.
In addition to housing beneficial fungi, this soil layer hosts detritus feeders like beetles and worms, whose activities in decomposing provide “bioturbation,” effectively tilling the nutrients from the organic matter into the soil below. Further, a mulch layer creates warmth as it breaks down, meaning the root ball of perennial plants below is better insulated during the winter.
There are few places in nature where the soil is bare and exposed to the elements: deserts are one of the only biomes that spring to mind. This natural mulch layer holds moisture and houses life. A healthy soil ecosystem starts with a top-dressing of organic matter, and autumn is the time when those materials are most abundant.
“And don’t think the garden loses its ecstasy in winter. It’s quiet, but the roots are down there riotous.”