Tuesday, July 7, 2009

mulch season

Grass clippings used as mulch.

People have written the Forge Farm Initiative in the past to ask about mulch: What is it, what does it do, and which materials can be used?

Mulch has a few basic roles in the garden: It moderates the soil temperature, holds in water, suppresses weeds, and provides a small amount of nutrients. July really is mulch season. With that sun blasting down and the rain sparse, you need something there to protect the roots.

There are a number of different kinds of materials you can use for mulch. You can buy bagged mulch, but I don't recommend that for a couple of reasons: One, it's pricey; there are free options out there. Two, some mulches can come with noxious weed seeds in them. A neighbor recently had a bad experience with commercial mulch: It came with seeds of Canada thistle, which is one of the most tenacious and evil invasive weeds out there. Impossible to get rid of.

Some use plastic sheeting as a kind of mulch, but I don't. I want to use a mulch that will decay and offer something to the soil microbes after I'm done with it. Plastic sheeting is just headed to the landfill at the end of the season.

But there is no shortage of free mulches available to you. Here are a few:

  • Grass Clippings: Collect them from a neighbor with a clean, pet-free lawn right after the neighbor has finished mowing. Bagged lawn clippings will quickly go sour -- that doesn't necessarily mean you can't use them, but they will mat up and smell for a day or three.
  • Shredded Newspapers/Cardboard: Perhaps not the most attractive mulch, but it is effective.
  • Shredded Leaves: You might want to avoid oak leaves, which could leach tannins and acids into the soil.
  • Pine Straw: Great for acid-loving plants, like blueberries.
  • Coffee Grounds: Ditto.
  • "Living Mulch": Some people are advocates for shallow-rooted plants that carpet areas around vegetables to suppress weeds and provide nutrients. One example is Dutch White Clover, a low-growing clover that fixes nitrogen in the soil. You can buy clover seeds at garden stores, like Valley View Farms.

With any mulch, you want to make sure that you are choosing clean materials, because this will touch your food (like lettuces and cucumbers, if they lay on the ground).

Mulch is also a great way to eradicate weeds in a particular area, or prepare new ground for garden beds. That method is often called "sheet mulching." We'll offer a recipe for sheet mulch in a future blog.

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