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In autumn, it’s not all about the leaves – at least not in my garden. Yes, I gather dozens (and dozens) of bags of leaves each year for use in my veggie and flower beds, as well as my compost bins, but there is another source of organic material on my property that provides a long-lasting natural mulch that also retards weed seed germination. What is this botanical wonder you ask? Pine needles! Growing right next to my driveway is a mature eastern white pine tree, a lofty evergreen that has the agreeable habit of dropping its oldest needles every two years. As autumn winds loosen those spent needles, I quickly rake them up to scatter around the garden.
All pine trees shed their needles, but depending on the species, it may be between 2 to 5 years before you’ll be able to gather the pine straw, the name for fallen needles, from your trees. For example, Jack and scotch pines shed their needles every two years, Austrian and red pine every four years, and mugo pine every five years. As mentioned above, my eastern white pine gives me about four large garbage bags of needles every two years. Garden gold!
Another lovely trait of pine needles is that they contain terpenes, a substance which inhibits seed germination. This helps reduce weed growth around plants like roses, perennials, asparagus, shrubs, veggies, and annual flowers.
Common lore is that pine needles acidify soil and you should only use them on acid loving plants like blueberries and rhododendrons, but fresh pine needles are only slightly acidic. Once they fall, they lose any lingering acidity and make a beautiful and effective mulch.
How do you use pine needles in your garden?