Mulch, compost ingredients take consideration

posted June 18, 2018 8:11 a.m. (CDT)
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by / Bev Carney | Gardening Columnist

Can I use kitchen scraps like eggshells and coffee grounds in my compost pile?

Yes, you can use kitchen scraps in a compost pile. In order to avoid attracting critters to the heap, its best to use a closed system like one of those recycled black plastic composting units that cities and towns frequently distribute or an enclosed tumbler system. Regardless of what container you use, food scraps should be combined with other ingredients. Note that some ingredients like egg shells or banana peels seem to take forever to break down. Our finished compost often contains large chunks of eggs shells, but we use it anyway. Larger items like cabbage cores and melon rinds benefit from being chopped into smaller pieces. There is no need to wash egg shells or any other foodstuff. Coffee grounds are a fabulous addition. A compost heap made solely of shredded leaves and coffee grounds will cook up into a usable compost in record time.

An ideal compost heap has a ratio of wet/​dry ingredients, also known as a ratio of green (nitrogen) and brown (carbon) ingredients. A good ratio would be around 25 percent nitrogen-rich products to 75 percent carbon products. That can be tough to achieve. A pile that is mostly nitrogen-rich materials like grass or food scraps will turn slimy and turn into a wet gooey mess. Mix food scraps with dry, carbon-rich materials such as straw, shredded leaves, or even pieces of cardboard or paper. This is not to say that every time you add kitchen refuse to the pile, you also have to add a handful of brown ingredients. This may be ideal, but not always possible. We compost in bins and are quite haphazard about adding enough brown material, but our compost does turn out fairly well after a year or so. For a list of which ingredients are nitrogen-rich and which are considered carbonaceous, see http://​​composting-chart.

Instead of using a composting system for their food scraps, some folks turn to indoor worm composting. This could be a fun and educational project for adults and children alike. Planet Natural offers this guide to vermicomposting: ​​worm-composting.

Can pine needles be used as mulch? What about grass clippings?

Both pine needles and grass clippings can be used as mulch, but they act differently in the garden. Pine needles make lovely lightweight mulch that doesn’t compact. Down south, bales of pine needles, known as pine straw, are sold in the garden centers. While these acidic needles make a great mulch for acid-loving plants like blueberries, science has shown that as the needles decompose they become less acidic and more neutral. They may add a wee bit of acidity to the acid-loving blueberries, but not much so they can be used anywhere. They’re also lovely in pathways, releasing a slight scent of pine as you stroll through the garden.

Provided your grass hasn’t been sprayed with a seasonal weed and feed product or some other chemical, grass is an excellent mulch product although it does take a bit of preparation before using. Green grass clippings will quickly start to rot if left in a pile. Ideally, use clippings that have dried while lying on the lawn. If you want to use clippings that have been collected as you mow and are therefore quite wet, spread them thinly in the garden so they will dry. If you plan to use the clippings, don’t select the “mulch” option with your mower. That will produce very tiny bits that could break down too quickly to be all that effective.

Beverly Carney can be reached at

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