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Master gardener in training: The minutia of mulch

May 13, 2010 | 10:22 am

Digging As readers of my posts know, I'm enrolled in UC Extension's Master Gardener program and sharing some of the lessons here.

In a recent class on backyard orchards, our speaker, Tom Spellman from Dave Wilson Nursery, began with an impassioned plea for mulching. Rather than spend hours making his own compost, he gets a $10 truckload of mulch and spreads it up to a half-foot thick throughout his home orchard. The benefits are obvious, he said.

MG_Mulch_Detail“It does three things: It keeps your ground temperature during the warmest part of the summer cooler by 15 or 20 degrees," he said. It also makes better use of your irrigation water by 50%, probably saving $25 a month on the water bill. And it "brings back the bioactivity in your soil" while making trees more resistant to disease or pests.

Mulch is not compost, although it will become compost when it breaks down. Whereas compost gets mixed into the soil, mulch sits on top, offering protection from the sun along with natural weed suppression. And just as with compost, mulch choices abound.

Organic mulch should have no more than 15% of any one type of material — horse stable bedding, eucalyptus leaves, wood chips and the like. Select the largest grind possible. If you have pets, avoid cocoa mulch or coco coir mulch. Both can be toxic. Use eucalyptus or oleander mulch in areas where you don’t want anything to grow.

You can get free mulch from the city of Los Angeles or get in touch with a local tree service company such as Marcuson Tree Works. Josh Marcuson, the U.K.-trained arborist in Elysian Park pictured at top, runs his trimmings and cuttings through a chipper and delivers the mulch free to Farmlab, local residents, community gardens and schools. He avoids dumping charges, and gardeners get a mulch blend that has been vetted by an expert. Anytime is a good time to mulch, he says, even before you plant. The mulch conditions and softens the soil.

Friday: backyard orchards.

-- Jeff Spurrier

Photos: Ann Summa

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