May is for Mulching: A Guide to Groundcover

May is for Mulching: A Guide to Groundcover

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Tess Wilson
May 27, 2015

Three and a half decades of city living left me completely unprepared for the importance that mulch would someday have in my life. Now that I have vegetable and native flower gardens, I find myself stalking the local municipal "free wood chips" pile, filling truckload after truckload, pricing out hay bales, and other dirty jobs. But if it keeps our gardens health and weed-free, it's (mostly) worth it...

Here are the eight most widely recommended types of mulch, along with eight extremely thorough sources with all the answers to your most pressing mulch concerns.

Salt Hay: Martha Stewart recommends salt hay, "You can prevent your garden paths and rows from becoming excessively muddy and compacted by mulching them with salt hay." but with the caveat, "Never use feed hay for your mulch. It is extremely invasive and packed with seeds, meaning it will self-sow within days and become very hard to get rid of." I had no idea what she was talking about, so luckily Horticulture Magazine was able to clear things up: salt hay "consists of grasses harvested from salt marshes. Their wiry stems do not mat down or rot as quickly as straw, and any seeds that are present will not germinate because they require wet, saline soil."

Leaves: Margaret Roach of A Way To Garden points out "Leaf mold, as the rotted stuff is called, is both a great mulch and soil amendment." She advises composting leaves separately (chopping them up with a mower if desired) from food waste to create an excellent mulch. Rake the leaves in the fall, let them decompose all winter, and you'll be all set for spring. However, Mother Earth News cautions that "black walnut leaves should be avoided because they leach chemicals that inhibit the growth of tomatoes and many other plants."

Grass Clipping: If you have to mow, you might as well get something out of it, like a big, beautifully-scented pile of free mulch. Fine Gardening says, "Grass clippings are great for vegetable and herb gardens. Clippings will decompose over the summer and can be tilled into the soil, increasing organic matter for future plantings."

Newspaper: Recycle your papers in the garden! Mother Earth News sings the praises of this method: "When formed into little tents, newspaper mulch can protect your crops from the glaring sun. As mulch, recycled newspaper is one of the best weed-controls available... newspaper mulching also regulates the temperature of the soil, adds fertility, and conserves moisture."

Pine Needles/Straw: This one appeals to me the most because I love the look and fluff of a needle-blanketed forest floor. As This Old House informs us, "long-leaf pine needles work best around acid-loving trees, shrubs, and perennials, such as Japanese maples, witch hazel, and delphiniums. The reddish-brown strands look especially natural on wooded properties."

Wood Chips/Sawdust: Mother Earth News has a very in-depth discussion of wood-based mulches that reminds me of how much I hated chemistry class in high school, but it's an invaluable bit of research. The main takeaway is the tagline: "In the short term (two years), wood mulch can potentially lower soil fertility, but in the long term their value in building garden soil is beyond question." Even I can understand "beyond question!"

Cocoa Hulls: I'd never heard of cocoa mulch until today, but now I need all of it, all over my garden because according to This Old House, "the shells of cocoa beans release a chocolatey scent as they decompose. Their rich brown hue darkens with age, adding contrast to your plantings." Lovely! But as The Saturday Evening Post points out, "Cocoa mulch is extremely toxic to pets, especially when curious dogs have access to the outdoors." That whole article is scary, even for someone without a dog: what if one wandered into our yard, or a friend brought one over and I forgot about the mulch?!?

Hazelnut Hulls: The by-product of all that Nutella, hulls are "Good for general use and ideal for paths because hulls let water through easily and don't stick to shoes.", according to Sunset.

Mulch Don'ts:

I can hardly decide what to quote from this very opinionated "Mulch Mistakes" piece in Garden Design Magazine, so you might have to read the entire thing. The author explores the qualities of "Good Mulch", "Bad Mulch", and "Ugly Mulch" and lists his most/least favorites. He is also very concerned that we're all mulching too much: "I think that gardeners are often too reliant on mulch. I started in the landscaping business more than 30 years ago and I have very clear memories of professional gardeners who carefully cultivated planting beds. Recently, cultivating beds seems to have been replaced by mulching, or perhaps I should say over-mulching." Perhaps you should, good sir.

MULCH FAQs + HOW-TOs:

What type(s) of mulch do you prefer? We've tried the black sheeting but found it expensive and ugly, and this year we're going to do hay. Regular hay, not salt hay, just to shock Martha.

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