The annual ritual of raking up tree leaves and bagging them for recycling takes place in our neighborhoods every fall. But at my house, I gather as many leaves as I can from the lawn, driveway and front walk and rake them onto the garden. Autumn leaves are one of the best soil conditioners and mulches available—and they’re free.
Tree leaves contain up to 50 percent of the nutrients that the tree absorbed during the growing season, and as they break down, the nutrients are re-released back into the soil. In addition, leaves help to insulate the soil in winter and add important organic matter.
All tree leaves (except black walnut) can be used: leaves from small trees, such as honeylocust and birch, can be raked directly onto beds, while larger leaves like maple and catalpa should be raked onto the lawn and run over several times with the lawnmower to shred them before using them as mulch.
Don’t be too concerned about covering up your shade-loving plants with autumn leaves: they expect it. In spring, any areas that are heavily covered can be raked to fluff up the leaves, but as long as the leaf mulch is less than five centimetres thick, the plants will push right through.
Do's and don'ts
- Do make sure leaves are healthy before using them as mulch.
- Don't use leaves covered with powdery mildew, rust or tar spot.
- Don't add mulch to rock garden plants like lavender and dianthus, as wet leaves against their stems will cause them to rot.