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Mulch isn't bad, but mulch does not mean wood

Friday - 4/8/2011, 9:27am  ET

Spring's changing temperatures and your flowers

Mike McGrath, WTOP's garden guru


Meet Mike at Homestead Saturday, April 16!

Mike will give a free kitchen garden talk ("Grow twice as much in half the space.") and answer all your questions about mulch and other topical topics at 1 p.m. on Saturday, April 16 at Homestead Gardens in Davidsonville, Md.

Mulch isn't bad, but mulch does NOT mean wood

Amy in Bristow is one of MANY listeners who wrote in to say, "If mulch is so bad, what should I use for the beds in front of my house?"

I never said "mulch" was bad, Amy -- just wood mulch. The problem is that wood and bark mulches have been heavily marketed to homeowners ever since landfills stopped accepting wood waste. So now all the dead trees, wooden construction debris and shipping pallets from China get chipped up, spray pained some God awful color never seen in nature and foisted on unsuspecting homeowners, where the mulch kills plants and stains homes and cars with impossible to remove artillery fungus spores.

Save us from the jumping fungus

My warnings about wood mulch last week prompted a panicked Kristina to contact the WTOP help desk to write: "Mike McGrath's stories have us freaked out about using mulch around our house -- but I don't know what he suggests as a good alternative. I don't want the jumping fungus!"

Ha! Nobody wants the jumping fungus, Kris! Luckily, those home and car staining spores -- known as "artillery fungus" by the less poetic -- only spring out of wood and bark mulches. A mulch of yard-waste compost (like Maryland's great Leaf Gro product) will cover your bare soil perfectly, without covering your siding in tiny little tar balls.

Just remember: Mulch: Good! Wood Mulch: BAD!

Is free mulch good mulch?

Steve in Falls Church was one of MANY listeners who responded to my warnings about the dangers of wood mulch last week. He writes, "What do you recommend as an alternative? Can I use the free mulch I can get from a local county?"

You might be able to, Steve. You just need to take a good long look at it first, because people use the term "mulch" to describe a lot of different things. If the free mulch is chipped up wood, bark, pallets or roots, pass it by. It's bad for homes and plants. But if its compost mulch, made from local yard waste like shredded fall leaves, it's the ideal cover for bare soil. Compost mulch has a nice black appearance, feeds your plants naturally and won't cause damage to your home and car the way wood mulches do.

Mulch for flowers? Yes. Mulch for trees? No.

Joe in Stafford writes, "My wife wants to start planting flowers and get the yard ready for all to see. I've heard you say many times recently not to use mulch. What should I use for our flower beds and around the trees?"

Well, Joe, for flowers, compost mulch is the absolute best. Other good choices include pine straw, shredded fall leaves or one of the many seed and hull mulches, like cocoa bean, pecan or peanut shell.

But trees need no mulch, and trees will always do better without mulch. This God-awful trend of so-called "decorative mulching" is one of the unhealthiest developments in the landscaping world over the last 20 years. If the odd weed springs up around the base of a tree, just remove it with a sharp hoe. (The original herbicide -- and good exercise, too.)

No matter what, please don't mulch the actual trunk of a tree. Those "volcano mounds" of mulch will rot the bark and shorten the life of your most expensive and hard to replace plants.

The 10 Commandments of Mulch

  1. Wood and bark mulches breed fungal spores that stain homes and cars. They steal food from plants, they attract termites and plant-eating voles and they can be a fire hazard.
  2. Rubber mulches are even worse. They are toxic, fire prone and they stink in the summertime.
  3. University studies have conclusively shown that two inches of black yard waste compost suppresses weeds just as well as two inches of shredded wood without any of wood's negative effects.
  4. The second best choice is shredded fall leaves. They prevent weeds perfectly. The earthworms they attract will live under the mulch, constantly improving your soil and feeding your plants.
  5. Dried grass clippings work very well and look especially attractive, but they MUST be from an herbicide free lawn or else they'll harm your wanted plats. And they must be dry (brown in color), otherwise they mat down into a slimy mess. Air-drying for a day is generally all that's required.
  6. Pine straw is THE mulch of choice down South, and is another excellent choice.
  7. The many seed, nut and hull mulches are also great. Pecan shell mulch is also big down South, and nitrogen-rich peanut shells will feed your plants as they prevent weeds. I love cocoa hull mulch, but don't use it if you have a dog that eats your mulch -- chocolate in any form is bad for dogs.
  8. Don't allow ANY mulch to touch ANY plant. And never apply any mulch deeper than two inches. That's not gardening, its assault with intent to kill!
  9. Don't run any mulch right up to the side of your house; it becomes a super-highway for hungry termites, keeping their traveling soil moist as it leads them to your framing.
  10. If you fall for the wood or bark mulch scam, be warned that your mulch WILL breed nuisance molds. Some of these are harmless, one is totally pornographic, and the most common -- artillery fungus -- will stain any light colored object -- like your siding or your car -- within 30 feet of the mulch. Irrevocably. Like, forever irrevocably. Don't believe me? Like Casey Stengel said, "You could look it up."
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