2 min read
April showers bring May flowers, but you know what else helps? A nice layer of mulch in garden beds and around trees. I was out there last weekend, taking advantage of the mulch sale at my local home center, spreading five big bags of the stuff around the mix of thorny bushes, lilacs, and evergreens that form the border around our back patio.
The mulch will help keep weeds down, prevent soil evaporation, and regulate soil temperature as warmer weather moves in, according to our experts in the Home Improvement and Outdoor Lab.
For all the benefits of mulch, there is one mistake many novices make when applying it—laying it on too thick. Indeed, when it comes to mulch, the old idiom “too much of a good thing” definitely applies. That’s because a heavy blanket of mulch will prevent water from reaching the soil.
“Thick mulch may also reduce air circulation and smother the roots of the plants it covers,” warns the Cornell Cooperative Extension. Harm from over-mulching is especially acute with shallow-rooted plants, including rhododendrons and azaleas.
The recommended thickness of mulch varies by plant. A couple of inches of mulch is safe around woody plants, including shrubs and vines. One to two inches is ideal for perennials in the flower garden, while one inch is best for vegetables and annuals. In any application, it’s important to keep the mulch away from the crown of the plant so that it stays dry, preventing rot, disease, and damage from rodents or other pests.
One of the most common sites of over-mulching is around trees, in the form of volcano-shaped piles that many people like the look of, not realizing the dangers. The correct method for mulching trees is to spread a few inches of material in a circle around the trunk at a minimum diameter of three feet. Then brush away the mulch from the base of the tree so that the circle forms a slight depression. This will maintain all the benefits of mulching without jeopardizing the tree’s root system.
One final warning about mulch: the material can turn sour when it is left to sit outside in a pile for too long, allowing fermentation to set in. The “toxic mulch” that results from the process is harmful to plants, so it’s best to apply mulch as quickly as possible after returning from the home center.
Having written thousands of product reviews and how-to articles on all aspects of home ownership, from routine maintenance to major renovations, Dan (he/him) brings more than 20 years of industry experience to his role as the director of the Home Improvement & Outdoor Lab at the Good Housekeeping Institute. A one-time roofer and a serial remodeler, Dan can often be found keeping house at his restored Brooklyn brownstone, where he lives with his wife and kids.
Comments are closed.