Mulch blocks weeds, regulates soil temperature and moisture, fights erosion, and keeps my garden looking neat. “Mulch is the solution to so many gardening problems,” Joe Lamp’l states in Gardens that Make a Difference, a good layer of mulch will keep the soil temperatures in my garden as much as 10 degrees cooler this summer and help prevent disease in my plants.
But does it matter what kind of mulch you use?
Mulching options expand every year. This year I’m really trying to think through my options. The relatively low-priced shredded cypress—one of the most popular mulches on the market—is one to be avoided because of it s high environmental costs. According to University of Florida data, the timber industry grinds nearly 3 million more cubic feet of cypress than it replaces every year to produce mulch. Slow-growing cypress, which stores and filters water and provides a vital wildlife habitat, is difficult to replace.
Here are just a few options to consider depending on your location and application:
Renewable eucalyptus grows rapidly on commercial plantations, and its pleasing scent deters fleas and other lawn and garden pests. Eucalyptus ages from golden yellow to reddish tones and may need to be replaced before the season’s end because it settles into the soil.
Exotic Australian melaleuca, or paperbark tea tree, has invaded more than half a million acres of Florida wetlands. Forestry Resources of Fort Myers, Florida, has joined environmental groups seeking to remove melaleuca and turn it into mulch. Termites do not favor melaleuca, the mulch will not significantly alter soil pH, and it holds its shape well. Known as FloriMulch, it appears to be available from an increasing number of Midwest supplies.
Smell, shell-shaped cocoa hulls, available in larger garden centers, are the byproducts of commercial cocoa grinding. They contain 2.5 percent to 3 percent nitrogen, and their low acidity makes them ideal for roses. Snails and slugs are said to shy away from this mulch, but dog owners should beware. Cocoa hulls contain theobromine, the chemical that makes chocolate toxic for canines. Cocoa mulch may develop a layer of harmless mold that can be removed with water or raking.
Pine bark and needles
Usually obtained as byproducts of other lumbering uses, pine bark chips retain their shape and color longer than shredded wood mulches, and pine needles nourish acid-loving plants. Pine bark chips tend to float away in heavy rain, making them unsuitable for sloped landscapes.
Rubber mulch is an excellent way to safe-guard your children while playing on a playground. When used as recommended, rubber mulch is a safe, cost effective, and eco-friendly alternative to traditional playground coverings. KinderMulch is manufactured in the Midwest in Joliet, IL, from 100% recycled tires and is sold in a variety of sizes and textures.
Here are just a few benefits:
- Rubber mulch produces a significant cushion and bounce effect when a child falls on it, much safer ground cover than wood mulch, sand, or pea gravel.
- Rubber mulch does not need to be replaced every year.
- Rubber mulch does not splinter or attract termites.
- Rubber mulch will not grow mold or mildew.
- Rubber mulch drains water much more efficiently than other ground covers
But rubber mulch is controversial, with many people worried, as you are, about the material’s possible harmful effects. I’ve seen several studies that have declared rubber mulch to be non-leaching, non-flammable and non-toxic to both plants and animals, but all were sponsored by the companies that process the mulch. A Washington State University study indicates that rubber can leach chemicals that contaminate water and hurt marine life. Rufus L. Chaney, an environmental chemist at the U.S.D.A. Agricultural Research Service, says that his research shows that small amounts of zinc in rubber will leach into soil over time. If your soil is alkaline and starved for zinc, as many soils are in Western states, that could be a good thing. But if your soil is acidic and has an adequate amount of zinc, as is typical in the East, the zinc released by the tires could cause a chemical overload that kills shallow-rooted flowers, shrubs and vegetables. “Save rubber mulch for paths and playgrounds,” he says.
What’s abundant in your area?
Look into local resources such as straw, peanut and pecan shells, corn husks, chemical-free sawdust or composted manures. If you use freshly chipped wood, add a nitrogen fertilizer to offset decaying wood’s tendency to tie up soil nitrogen. Many local landfills, municipalities and recycling centers provide free tree waste mulch – especially with the removal of emerald ash bore affected ash trees in Michigan, Ohio and Indiana. Although the free mulch is not colored like commercial mulch, the tend to look the same after a few months of rain and sun.
1. Allow soil to warm up a bit in spring before applying new mulch.
2. When mulching trees, mulch out to the tree’s drip line but leave a few inches bare around the trunk. If mulch becomes hard and matted, fluff to allow air and moisture to get through.
3. Always check your mulch’s freshness. If it smells sour or rotten, it could harm your plants.
4. Overly thick mulch suffocates roots. Most mulches work best in 2- to 4-inch blankets.
Peanut shells, cocoa hulls, and pine bark and needles make great mulch.