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Is Pine Needle Compost too Acidic for Vegetable Gardens?

Will pine needle compost give your garden a nutrient-rich boost, or is it a bad idea? The answer is... not what most people think.

Pine needle compost might be one of the most misunderstood areas of composting. Sure, there’s some confusion about whether that take-out container is compostable, but when it comes to pine needles, there’s a longstanding assumption that they are too acidic. 

Granted, that assumption is not without reason. At our cabin in Vermont where we spend our summers, I’ve had trouble starting a garden in parts of my yard because the pine needles just rain down constantly from June through September. They make great mulch but work a little too well. There’s a difference between purposefully using pine needles as mulch and covering your garden in blankets of pine needles every day. 

And if you’ve spent much time in a pine forest, you know that there isn’t a lot of undergrowth in these areas. Therefore, the reasoning goes, is that the soil is too acidic for anything to grow. Really, I think it’s because pine needles are solid mulch, not because they kill everything in their path.

The soil around pine trees is indeed acidic, but that’s because they enjoy acidic growing environments. Additionally, evergreen roots tend to run on the shallow side, meaning there’s more competition for other plants to establish themselves. And because these trees are evergreen and usually don’t allow a lot of light to get through the canopy, it’s just not a great place for other flora. 

So now that we’ve debunked that myth, let’s talk about whether or not you can use pine needle compost in your vegetable garden.

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Using pine needle compost in your garden: Yes or no?

First off, yes, pine needles are acidic. And if you used pine needle compost exclusively, it might be too much for your veggies. But pine needles have some wonderful benefits for your garden, including as a compost ingredient

Before you think about composting them, however, I should point out that pine needles make superb mulch, like I said before. Like most any other mulch, they improve moisture retention in your soil, stabilize soil temperature, help control weeds, and they break down slowly, so you won’t need to mulch as often. 

For pine needle compost, it’s that last item that you need to be aware of. The waxy coating on the needles, known as a cuticle, makes it difficult for microorganisms to do their decomposition work. You can speed up the process somewhat by waiting until the needles are dry before you rake them up and add them to your compost heap. You can also shred them by running over them with your mower. 

What this all means is that if you add pine needles to your compost bin, they may still be partially intact while the rest of your compost is ready to go. But do you need to worry about that lowering the pH of your soil?

The truth about pine needles in your compost

Even though pine needles are acidic, as they break down, they lose some of that acidity and may even approach a neutral pH.

Amy Jo Detweiler, extension horticulturist at Oregon State University, says that as long as you limit the pine needles to about ten percent of your compost pile, they are unlikely to have much impact on the acidity of your garden soil. 

Ultimately, whether you need mulch or compost, pine needles are a great (and FREE!) source of materials. Just don’t overdo it. 

Have you used pine needles in your compost? How do you think it impacted your plants? I’d love to hear your story in the comments. 

Discover 7 top tips for growing, harvesting, and enjoying tomatoes from your home garden—when you access the FREE guide The Best Way to Grow Tomatoes, right now!

By Amanda MacArthur

Amanda MacArthur is Senior Editor & Producer for Food Gardening Network and GreenPrints. She is responsible for generating all daily content and managing distribution across web, email, and social. In her producer role, she plans, edits, and deploys all video content for guides, magazine issues, and daily tips. As a best-selling cookbook author, Amanda cooks using ingredients from her outdoor gardens in the summer and from her indoor hydroponic garden in the winter.

11 replies on “Is Pine Needle Compost too Acidic for Vegetable Gardens?”

Such great input! Thank you all from an amateur…always needing schooling. I have a huuuggggee blue pine in my front yard and pine needles so deep it’s like walking on a deep pile carpet… yep…nothing will grow except wee pinecones…ha ha ha…however…I never thought about using it for mulch or adding it to my compost…thanks again!

We have lived in central Florida for over fifty years and pine needles have been a useful ground cover. The article and research is correct. Too much keeps anything from growing except insects and our best friends, the black snakes. We have been mixing the pinestraw with other clippings and find that the mulch works great. Mix the straw with green grass clippings and leaves off the cherry bushes works well. Here’s a cool point about pinestraw. When the straw gets real thick I roll it back like a rug, shovel up a bucket of the black, rich soil under it for planting new seeds or cuttings then roll the needles back in place. I have so much pinestraw mulch I share it with neighbors.

Great information. We just moved to Ocala and I’m thinking that pine needles could be good to collect for helping apply to the sand along with some other organic material to complement the sand for a vegetable garden. I need something inexpensive to slow water seepage and allow the Florida sand “soil” to keep moist for plant growth.

I live in semi-arid Colorado and my soils have a pH between 8 and 9. Acid needles from the pine tree in my back yard are a much cheaper way to neutralize that pH then constantly adding store-bought ammonium sulfate.

My pine needles are black from years of being buried under newer needles that naturally fall from ponderosa pine.they crumble easily in your hand. Will veggies grow OK in them.my soil is clay so I added the needles in trenches 12 inches deep.should I add soil before planting?

Using pine needles, aka pine straw, is a frequently used mulch in the South. It does inhibit growth if used too thick. Also, snakes like to hide in it and copperheads have the same coloring, so don’t put it near walkways. According to several sources I looked at the “acidity” is not even enough to change the color of hydrangeas so I don’t think one would need to add lime.

When I put pine needles in my compost pile, I mix up a bucket of lime water and pour it over top of the needled to offset the acidity.

Never even thought of using them as a mulch! I add small amounts to compost though with no problems. My allotment seems to like it. But it is probably about that 10 percent mark.

I have mulched my raised beds with pine needles. They smelled good and the garden looked very neat. They decomposed fast and working the soil I saw strings of mycelium. This was a winning situation. Now I do not have access to pine needles but if I did I would use everything.

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