Easy On the Mulch


By Charles Kidder

My nephew received a message from his community association in Birmingham, Alabama, reminding him that it “was time to freshen up your pine straw” to avoid that tired, bleached look. Good grief. There are many good reasons to mulch, but aesthetics is hardly high on the list. Then why should you mulch your garden?

Mulch conserves water, reducing evaporation from the soil by 15 to 20 percent. When nature provides rain, the drops don’t hit the soil directly, reducing erosion. Also, reducing the splashing of soil and fungus up onto foliage can cut down on plant disease.

Large changes in soil temperatures, especially from below freezing to above as frequently occurs in the fall, can heave newly-planted perennials out of the ground. The insulation provided by a few inches of mulch reduces fluctuations in soil temperature, both over the course of a single day, as well as from summer to winter.

Organic mulches—leaves, wood chips and bark—improve the structure of your garden’s soil and provide a better home for the critters that live in it. And those both lead to healthier plants. Inorganic mulches, such as stones, don’t provide any of those benefits and usually look out of place in anything other than a rock garden. That’s not to say that you can’t add large rocks to your garden as decorative elements, of course.

So, given that we are pretty much restricting ourselves to organic mulches, what’s the best one? You’ll see a lot of debate on this, but as far as your plants are concerned, it pretty much boils down to “carbon is carbon,” meaning that the exact type of organics doesn’t matter a whole lot. For example, I might use shredded hardwood on my beds, but put pine mini-nuggets on paths. One caveat: some sources say that compared to hardwood, pine bark on a slope is more apt to wash away in a heavy rain.

There are a couple of types of mulch I would avoid, however. One is cypress, available in bags at some big-box stores. There is at least one website devoted to the evils of cypress mulch, which has nothing to do with it damaging your plants. The issue: bald cypress is not a particularly common tree, being restricted to southern swamps. It does not regenerate rapidly and is vital to the swamp ecosystem. It is a waste of a good and magnificent tree to grind it up and throw it on your garden.

The other mulch to avoid is dyed, be it either red, brown or black. You pay a lot more for color, and who wants to make mulch the focal point in their garden anyway?

Although I would not necessarily totally reject leaf mulch as offered by the City of Charlottesville, there is one drawback. When those leaves get sucked up from the gutter, a lot of other stuff comes along for the ride—rocks, plastic, you name it. Not that it’s likely to harm your plants; it just doesn’t look very nice.

Regardless of the material you pick, there are two somewhat different philosophies on the purpose of mulch. I value it for providing a relatively inhospitable place for weeds to germinate, so I want something that is not broken down too much. But in talking with Crozet’s Cottage Gardener, she favors mulch that is tending toward compost, so that it provides a good substrate for self-seeding annuals and perennials. Notwithstanding, I get plenty of volunteers coming up in my mulch.

When purchasing mulch you also must choose between either buying in bulk by the yard, or in bags that typically contain two, or occasionally three, cubic feet. Buying in bulk is certainly cheaper. For example, John W. Clayton & Son of Ivy will deliver nine cubic yards of hardwood mulch to Crozet for about $294, including tax. If you bought an equivalent two palettes—about 130 bags—of mulch from Home Depot in Waynesboro, it would run well over $400 delivered. (Note that the delivery charge of $65 is the same for one palette or ten, as long as it fits on one truck.) Either way, you would have a lot of mulch to deal with. And for planning purposes, one cubic yard of mulch covers 108 square feet to a depth of three inches.

There are some advantages to buying mulch by the bag. One is that you may not really have room for a nine-yard mountain on your property. If you need just a little bit, a few bags can go into the trunk of your car or into the back of your truck. Another plus is ease of moving. With bulk mulch, it has to be forked into your wheelbarrow to move it around. With the bags, you can just pick up a bag or two for a short distance, or toss them into your wheelbarrow for a longer haul. A tip: if you do have to load loose mulch, the job goes faster with a 16-tine ensilage fork, rather than a pitch fork.

Mulch should be spread no more than three inches deep, and that’s assuming you are starting with totally bare soil. If you are just re-applying over old mulch, one or two inches might do. Remember not to cover up the basal foliage of perennials and to keep mulch away from tree trunks. Mulch volcanoes around trees can provide a hiding place for gnawing critters and diseases. If you’re dumping mulch around many small, newly planted perennials, put the empty plastic pots over the little plants. This will reduce the chance of running your wheelbarrow—or foot—right over the little guys.

Mulch is indeed good for your garden. Just don’t let it become an end, rather than the means!