In most respects, having trees on your property is a pleasure. They provide shelter from the summer sun, which can help reduce your air-conditioning and lawn watering costs. They also provide a habitat for birds, squirrels and many other small creatures. However they also make work, dropping buds, blossoms, fruit, nuts and leaves or needles at various times of the year. Most of these can easily be composted, but pine needles present a few special challenges.
Pine needles are unlike most other forms of natural yard waste. They're slow to decompose because of their waxy coating, which makes them an excellent mulch around plants but a challenging compost ingredient. They're also highly acidic, which prompts two further considerations. First, the bacteria that turn plant matter into compost are sensitive to acidity, so pine needles slow decomposition and prolong composting. Second, pine needles lower the pH of your compost to a degree that few garden plants will accept.
Composting Pine Needles
This doesn't mean pine needles have no place in your compost. They can be mixed into your regular pile along with other forms of yard waste, provided they don't account for more than 10 percent of the pile. If possible, chop the pine needles by mounding them up and running over them with your lawn mower. The smaller they're chopped, the more quickly they'll decompose. If your garden contains plants that flourish in acidic soils, you might want to build a separate compost pile for pine needles.
Making a special compost pile for your pine needles isn't fundamentally different from making any other compost pile. Chop the pine needles, if possible, and mix them with grass clippings, green leaves and vines or stems culled from your garden. Layer these with carbon-containing compost items such as straw or dried leaves, and keep the pile moist. The pine needle pile breaks down more slowly than conventional piles, but it will eventually produce a fine, acidic compost. Use it around strawberries, azaleas, gardenias and other plants that prefer an acidic soil.
The simplest and most natural way to compost pine needles is simply to leave them where they fall at the base of the tree. They'll automatically form a layer of natural mulch around the tree, beginning a few inches from the trunk and extending all the way to the tree's drip line. This is exactly how mulch should be applied around a tree, according to Missouri's Department of Conservation. Over time the needles will decay into compost, fertilizing the tree.
Fred Decker is a trained chef and certified food-safety trainer. Decker wrote for the Saint John, New Brunswick Telegraph-Journal, and has been published in Canada's Hospitality and Foodservice magazine. He's held positions selling computers, insurance and mutual funds, and was educated at Memorial University of Newfoundland and the Northern Alberta Institute of Technology.