It’s time to mulch.
Over the weekend, I put all my plants in the garden soil, still soggy from last week’s spring rains. I want to lock in that moisture and stop the weeds that are already poking up between the strawberries and the kale. 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 “Garden to 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.
My mulching options expand every year. I’ll avoid relatively low-priced shredded cypress—one of the most popular mulches on the market—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.
With help from Natural Home & Garden’s great article, “Mind Your Mulch,” I’m weighing the pros and cons of the following environmentally friendly mulches. What’s your favorite?
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’s available at gomulch.com.
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.
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 and recycling centers provide free tree waste mulch.
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. Photo by Joe Coca