UMCA News Release

Missouri's mulch of the future? Pine straw, MU researchers say

COLUMBIA, Mo. - Steven Kirk talks about pine straw with the evangelical fervor of an old-time preacher.

"It's the mulch of the future in Missouri," he told a group of Missouri Master Gardeners during a pine straw demonstration at the northeast corner of Ellis Library on the University of Missouri campus. "It has a lot of advantages over conventional bark mulch."

Pine straw has long been the landscape mulch of choice in the southeastern United States, where long-needled pine species thrive. "This pine straw is all Missouri-grown," Kirk said. "It comes from loblolly pines grown in the Bootheel. They're not native to Missouri, but they can grow in parts of the state."

At $9 per bale, pine straw might seem more expensive than bark mulch, which retails at about $3 a bag, he told his audience. "But we're going to see how far one bale goes as opposed to a bag of bark mulch. Then, you can do the math."

Kirk spreads a 3-cubic-foot bag of bark mulch and measures the coverage area: 15 square feet at a depth of 3 inches. The pine straw bale spreads over about 50 square feet at a depth of 4.5 inches. "If it's raked out, it will cover 60 to 70 square feet."

"It shouldn't be any more expensive in terms of coverage," said Dick Munson, MU director of Landscape Services and the MU Botanical Garden. "It's my favorite mulch of all the organic material I've used. I think it's by far the most attractive. It's very effective, and I really like the way it smells, especially after a rain."

Meredith Ludwig of Creative Gardening Design and Nursery in Boonville, Mo., was a pine straw enthusiast before she came to the demonstration. For one thing, she said, pine straw comes in bales instead of "these nasty plastic bags that are not recyclable."

"It definitely spreads faster, sweeps up easier, and it won't stain the pavement," Ludwig said. "And it doesn't get as hard as a rock over time. Even after it's been out for a month and been rained on a couple of times, it's still pretty fluffy."

That characteristic has a practical benefit, said MU horticulturist Mary Kroening, coordinator of the Master Gardeners Program. "Bark mulch tends to make a seed bed for weeds," she noted. "With pine straw, the weed seeds fall through and don't take root. Pine straw is not conducive to weed growth."

Nor is it a favorable habitat for garden pests, said Kirk, a graduate student in horticulture. He cited studies that indicate slugs and snails do not thrive in pine straw, and that termites prefer bark mulch to pine straw.

He added that pine straw is a renewable resource that ultimately provides a more balanced soil pH than bark mulch. "Pines shed needles every year, but hardwood trees don't naturally shed their bark. Pine straw is more like the natural cycle."

Another aspect of Kirk's research is to find long-needle pines species that grow well in Missouri. At MU Bradford Agronomy Research Center, he has worked with loblolly pines crossed with pitch pines, and his preliminary findings indicate those crosses will come into full production about eight years after planting.

"He's got some fast-growing pine trees that are hardy here in Missouri," Munson said. "Once you get enough trees, pine straw will become commercially viable around here. When people see what it looks like in the landscape, the demand will grow and the commercial folks will say, 'Here's a viable product we need to stock.'"

Sources: Steven Kirk (573) 884-9406, Dick Munson (573) 884-6307 and Mary Kroening (573) 882-9633

--Forrest Rose
Information Specialist
(573) 882-6843
RoseF@missouri.edu