Sheet Mulching
Sheet mulching is the practice of depositing one or more layers of organic material, such as cardboard and burlap, over herbaceous vegetation and then burying the layers in wood chips. Unlike occultation (or solarization), sheet mulching does not require later removal of any materials, because the cardboard and wood chips break down in place, conditioning the soil as they do so. While increasing underground water and nutrient availability, the materials smother underlying vegetation and cause complete mortality over one to several seasons, paving the way for a new plant community to be established. Wood chips become inoculated with diverse fungi species and promote excellent soil health in the long term.
We particularly enjoy using this treatment in the pollinator hedgerow that surrounds the perimeter of the meadow. First, we weed the area (at least) 8 inches around the base of each tree and shrub. Cardboard (which must be free of tape, glossy coatings, or any other inorganic substances) can then be laid out so that only the stems of the desired woody plants are uncovered. Spreading a deep layer of arborist chips over the cardboard (at least 6 inches deep) causes explosive growth in the absence of competition from exotic grasses and herbs. Be sure to keep wood chips off the bases of woody plants, which may rot if wet chips are in direct contact for long periods.
Our 2026 sheet mulching experiment will assess whether wood chips can successfully suppress and control pasture grasses without cardboard or burlap being laid down first.
After pulling grasses and herbs from the bases of the trees and shrubs, we spread two layers of cardboard over the area before depositing and raking a deep layer of arborist chips out on top (top and middle left pictures). Middle right: Sheet mulching completed in a section of hedgerow in February 2024. Bottom left: Same sheet-mulched area in May 2025.
October 2024: Sheet mulching in the Northeast corner of the meadow and hedgerow, installed in late June 2024. On the left is an untreated area overtaken by pasture grasses and other herbaceous weeds; the trees and shrubs planted there have already dropped their leaves and show poor form and vigor. An adjacent area depicted on the right demonstrates how sheet-mulching (installed the previous June) successfully smothers choking understory vegetation.
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