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Pine Needles as Mulch

Pine Needles As Mulch

by Summer Brasuel

UCCE Master Gardener of El Dorado County

"Water, water everywhere, but nary a drop to drink" is a good analogy and sums up my thoughts when I look at all the pine needles on the ground but have been discouraged from using them as mulch because they lower the pH of the soil to acidic levels. Well, guess what? It's a myth! Green pine needles are acidic, but once they have fallen, and are dead and dry, the soil and microbes neutralize them. Go right ahead and use those pine needles as mulch. They are everywhere, and they are free!

We all know mulching is important. It prevents weeds, keeps soil moist and aerated, and can protect plants from disease. It also keeps plants cooler during the hot summer months, helps prevent soil compaction, and much more. Use pine needles like other mulch. However, ponder these considerations before you get started:

  • Pine needles decompose slowly so they do not have to be re-applied as often as other mulches. They also allow water to seep through easily.
  • Pine needle mulch is excellent in perennial beds such as strawberries and blueberries, around shrubs and trees, or wherever you have permanent plantings.
  • Mulching vegetable beds that are harvested daily may not be very practical because pine needles are prickly! You might prefer lawn clippings or leaves for these kinds of beds. Cutting pine needles into small pieces with your lawn mower or other shredder may make them easier to use in a vegetable bed.
  • If you want to add pine needles to your compost pile, they will take years, not months, to decompose. A good rule of thumb is not to add more than 10 percent pine needles to your compost pile.
  • Pine needles are slippery. Use them as a weed barrier in areas that are not well traveled, like between deer fencing and planted beds. Using them on walkways or slopes could be dangerous (hikers know about this!).

Pine needles can be flammable and are not recommended within 30 feet of the house. If you live in a forested area, then pine needles are all around. Like me, you probably rake them up and take them away from the house and outbuildings, which is the fire-safe thing to do. Good news is, now you know you can add them as mulch to garden beds in other areas without risking acidic soil.

Here are some resources to learn more about mulching:



The Combustibility of Landscape Mulches



Master Gardener classes are offered monthly throughout the county. You can find our class schedule at: http://mgeldorado.ucanr.edu/Public_Education_Classes/?calendar=yes&g=56698, and recorded classes on many gardening topics here: http://mgeldorado.ucanr.edu/Public_Education/Classes/

Sherwood Demonstration Garden is generally open March through October every Friday and Saturday of the month. We will offer tours, answer questions or you can just enjoy the garden. Please check our website for further information about the Sherwood Demonstration Garden at: https://ucanr.edu/sites/EDC_Master_Gardeners/Demonstration_Garden/