Pine needles-compost, mulch, or throw them away?

Running Springs, CA(Zone 7a)

I live in a mountain community and every spring, hundreds of bags of pine needles from every yard are sent away to the dump. I have been afraid to use them because I have been told over and over that they will make the soil too far to the acid side. It just seems like such a waste of organic material. If the needles are all brown and have been on the ground all winter, and if I chop them up with the oak leaves, would they be safe for the composter and safe as mulch for my veggies and flowers?

Durham, NC(Zone 7b)

I have to say from everything I learned in my soil science class that this is a myth - yes tons of pine needles will increase acidity in soil but only very slightly and if I remember correctly this took a long time. If you would like to me to, I am sure i can find more facts from that class, this was just from memory but Im fairly certain I can pull up the facts that made 'us' come to this conclusion... lmk :-) I personally have a 'flower bed' that is under a pine tree - I do not clean up the pine needles and have no trouble growing anything under there (except when the voles have eaten it)

Austin, TX(Zone 8b)

If you're growing plants that are native or adapted to your area, they'll be looking for soil which has been acidified by the pines anyways. Not to mention that the oak leaves are acidic, too. And that if the pine needles have been laying on the ground for months, their chemicals have been leaching out into the soil already, every time it rains. So I'd say keep them...

It's not a huge deal to get a pH soil test. You might want to do that now, just to see, and then if you're concerned you can repeat it periodically.

If your community is putting large amounts of organic matter into the landfill, possibly there are more effective ways to handle that solid waste. Landfills have to be contained, because some of their contents are toxic. So you're basically paying, forever, to sequester those fairly innocuous needles. More and more communities are processing their plant matter into some useful form, making mulch available to residents, free or at a small cost, or selling it through a large garden supply processor. There is overhead cost for any of that, of course, but it might be interesting to at least ask the question of your mayor or city council.

Running Springs, CA(Zone 7a)

Thanks to both for your input. I did some research online and found several articles on this topic. The opinions of all that I read were that the risk of high acid change in the soil is minimal. I am going to try using it for my flower beds, but I think I will continue to use leaves and straw for my veggies.

We live in a pine and oak forest, and our community has a continuing high risk of fire. We have very strict regulations about anything that will increase the fire hazard. During clean up season, thousands of bags of needles and leaves are raked and bagged. We have a "Transfer Station" that accepts all of our plant source refuse. It is then sent down the hill to another area where it is processed. I'm going to try to spread the word that there might be a way to put some of the needles to use as a free mulch. Most of the sources I checked preferred the pine straw to bark and I even found resources listed who sell it in bales specifically for the garden.

Hahira, GA(Zone 8b)

slopesower - Here in South Georgia, we use pine straw (needles) almost exclusively as mulch - it is wonderful! It does make the soil a bit more acid, but not drastically so - our soil here is acidic to begin with. It looks nice, smells nice, & decomposes slowly - I just add new on top of the old 2x each year. Our soil is very sandy here, & the pine needles sure help hold in moisture!! I would take it in a heartbeat!! I think to be very useful in composting, it would have to be chopped rather fine - they have a waxy coating that keeps them from decomposing quickly. Samantha

Charlotte, NC(Zone 7b)

During the mid-70's I lived in Tennessee and my vegetable garden was not far from a samll group of pine trees. I used pine needles exclusively in that garden with no problems, except with beets. I don't know why the beets didn't grow, perhaps the soil pH was off.

Here in NC, I use pine needles in my walk-ways - they give a nice "feel" under our feet and keep the weeds away. They are also used as mulch around our blueberries and strawberries.

The rest of the garden is mulched with compost, worm castings and leaves that have been through the mower a few times.

Bardstown, KY(Zone 6a)

I treasure my pine needles and oak leaves for mulch. I chop them up with either my bagging mower or leaf blower/vac. They make great mulch for all my flower beds. I very rarely have weeds when using this for mulching all my areas.


Savannah, GA

I compost pine needles, oak leaves, paper leaf bags sometimes, kitchen scraps, and other stuff. My piles are on the ground and are pretty big. It takes awhile for them to decompose but I wind up with a lot of black fluffy compost! I use the same stuff for mulch as well. I think the key is to mix the needles and leaves with grass and scraps.

Running Springs, CA(Zone 7a)

Thanks again for all of your responses. I have been using my leaf vac and have many bags of chopped oak leaf and needle mulch to use in my garden and my composters. I love the chopped leaves, but in the past, I spent so much time trying to separate the needles out because I was afraid of them. However, in the areas where the needles are thick, I have raked them up and plan to use them as mulch in my flower beds. They're free! And, they're right here where I need them. I'm anxious to see how things work out.

We keep getting teased with a sunshine, and then more cold weather. We're supposed to get snow again today, and a week of cool temperatures, so my spring gardening is going slowly. We want sunshine!

Charlotte, NC(Zone 7b)

slopesower - I live in zone 7b. I think we keep getting your weather!

Running Springs, CA(Zone 7a)

Honeybee, we keep sending you guys one storm after another. California has had a strange winter. We need the water, but it is getting old.

I've been looking at the veggie pictures on the Tomato thread and I have such zone envy. But I tell myself that my garden will still be thriving when theirs is done. But I can just taste those tomatoes.

Central Valley, CA(Zone 9a)

Quote from GardeningNC :
I have to say from everything I learned in my soil science class that this is a myth - yes tons of pine needles will increase acidity in soil but only very slightly and if I remember correctly this took a long time. If you would like to me to, I am sure i can find more facts from that class, this was just from memory but Im fairly certain I can pull up the facts that made 'us' come to this conclusion... lmk :-) I personally have a 'flower bed' that is under a pine tree - I do not clean up the pine needles and have no trouble growing anything under there (except when the voles have eaten it)

Coffee grounds doesn't lower pH either. In fact, the pH change of most OM takes a lot of time and material and only budges slightly.

Charlotte, NC(Zone 7b)

I can just taste those tomatoes.

Slopesower, I actually did get to taste my own tomatoes over the weekend - ones that had been frozen last summer.

If the slugs will leave the plants alone, I should have fresh-picking tomatoes in July. Last year I started over three times!

Running Springs, CA(Zone 7a)

Honeybee- I know what you mean about the frozen tomatoes. I just used the last container of the baked tomato sauce from last summer. If you haven't tried it, you need to. I got the recipe from here at DG and have shared it with many friends. We love it. I also made a baked sauce like it with my tomatillos since I ended up with so many.


Honeybee try putting coffee grounds around the base of your tomato plants to repel slugs and let us know if it works for you.

Charlotte, NC(Zone 7b)

chucki - I used coffee grounds last summer for the first time, and they really did work. However, hubby and I don't drink a lot of coffee, so they ran out pretty quickly. He has been saving our grounds all winter, and hopefully we now have enough for this summer.

I also used Sluggo Plus - which also killed the sow bugs. Unfortunately it doesn't work once it gets wet and we have to water at least every-other-day during the summer 'cause it hardly ever rains around here!

North Ridgeville, OH(Zone 5b)

I've heard slugs won't cross a barrier of egg shell pieces. Supposedly they dislike the sharp edges.


Honeybee is there no Starbucks or Seattle's best in your area?
I get 50 lbs at a time here.

Charlotte, NC(Zone 7b)

chucki - I actually pass a Starbucks on my way home each day - but I'd be mortified if I asked for their coffee grounds and got of of "those" looks :(

SE Houston (Hobby), TX(Zone 9a)

"Nothing beats a wish but a try!"

You don't know how glad they'd be to have a bucket with a lid sitting where they can conveniently dump the filters and grinds! Especially when they're running into each other with a store full of customers.

You're offering them a convenient solution!

Now, you've encouraged me for the last two weeks. I am EMPOWERING you to walk right into that Starbucks with your nice clean bucket and lid, and ask them to fill it for you!
And now's the time, 'cause the weekends are VERY busy and they'll go through LOTS of coffee grinds by Tomorrow night!

JUST DO IT! ^^_^^

Charlotte, NC(Zone 7b)

Thanks for the kind words, Gymgirl - my first task is to find a CLEAN bucket! I let them sit outside to catch rain water, and as you probably know, algae grows pdq (pretty darn quick) in open areas of standing water.

Y'all are thinking "mosquitoes" - and yes, they do harbor them, but we have bats/swifts/swallows on patrol each evening, so mosquitoes are not much of a problem.

We live near a greenway so there are lots of trees for nesting birds. I LOVE birds!

Central Valley, CA(Zone 9a)

Botulism is another problem with standing water that adversely effects wildlife. To cut down or eliminate mosquitoes, algae and botulim, create a system that allows for movement of water that introduces oxygen. An inexpensive water pump for ponds may help. Don't allow a build-up of decaying matter and fertilizers to drain into the pond.

Charlotte, NC(Zone 7b)

dlbailey - I didn't know about botulism being a problem in standing water. I wonder why I haven't heard of this before?

The National Wildlife Federation doesn't mention this, and I have tried to follow their guidlines for protecting wildlife in my own backyard.

Central Valley, CA(Zone 9a)

Botulism is a toxin from the botulinum bacteria. Its an anerobic bacteria that thrives in warm, wet areas with high OM matter. Botulism is an occasional issue with domestic poultry, especially in large facilities that have contaminated water or feed.

The reason I know that it is a problem with wildlife because both as at my undergrad and at grad school that had to repeatedly drain large ponds and cull ducks and geese that were effected. I have also heard of reported problems with migratory birds.

NWF may have left it out because its assumed to not be a problem in backyards. However, I infrequently hear of backyard poultry keepers losing animals to botulism after heavy rains or from stagnant ponds. Botulism is rare but under the right circumstances it can be disasterous.


Honeybee I was leary of asking for grounds the first time also. but the young lady at the counter went and got me a sack full and offered to carry it to the car for me.
they have to pay to get rid of it if gardeners don't use it.

Holyoke, MA

Hmm... I'm new to gardening, but I just bought a house that has a lot of pine trees which were barren underneath. I read that pine needles are acidic, so all I did is scatter some lime. In the fall/spring when I rake the yard into the compost pile, I just make sure to dump a good amount of lime into the compost as well. The grass has been growing well so far, and the compost is constantly sprouting random plants!

Baldwin City, KS

We are just beginning to experiment in using pine needles as mulch. We were concerned regarding making the soil more acidic so we used the needles as mulch on acidic loving plants--blueberries, azaleas and rododendrums. Still too early to really see the effects of this.


Kalispell, MT(Zone 4b)

I live in a Ponderosa 3 acres and have developed all of the beds underneath the pine trees. The reason nothing grows is not acidity but rather dehydration. The above tree collects the rain and it evaporates before hitting the ground. (at least here in Montana). I use a debris loader to "process" all of my pine needles and compost them. I run them through the debris loader (chips and shreds but takes 2 trips through with loader) The waxy surface of the needle will not let moisture in and therefore no compost pile will break it down until crushed, mowed, and shreded. Even then after all other compost material is cooked the needle remains and I feel that this is good because it creates soil structure that is excellent for worms bacteria and yeast/molds.

Thumbnail by Soferdig
Katy, TX

I have bags of pine needles and oak leaves every year. They did not go to waste. Farmers or people in the area that grow strawberries come by every week and pick up the bags. They put them under the strawberry leaves and berries.
This year I really needed them. My soil was getting compacted. Since I have more time than money, I gathered them and put them about 1ft. deep at a time in a large barrel and used my grass hog edger to break them up and dumped them in the beds and worked them into the top 8'' or so of soil. Worked like a charm. The pine straw is harder to break up than the leaves, but then they don't have to be broken up to small to do the work.

Charlotte, NC(Zone 7b)

char35 - One nice thing about pine needles is that the rain percolates down through them easily, which is not the case with leaves, especially the larger ones.

Everett, WA(Zone 8a)

As a kid, I tried to compost pine needles for years, with near-zero decomposition for 7 or more years. It was well-ventialted and I kept wtaering it. Even fertilized it. Turned it. Seeded it with dirt. Nothing.

The heap spread wider and wider, and got to be 4-5 feet high before I defied the conventional wisdom about "wasting nitrogen" and turned some lime into the top foot or so. It seemed like only a few days before the pile was half its height, 3 feet of needles turned into 8-10" of nice compost. That went onto flower beds promptly.

I reconsolidated the pile and sprinkled more lime: pile-be-gone, compost-be-made.

They say that liming a compost heap encouages any ammonaical breakdown products to off-gas as ammonia, but that was preferable to the entire yard being overwhelmed by immortal, mumified pine needles.

Kalispell, MT(Zone 4b)

Pine needles need to be crushed, cut or macerated. I have a debris loader that does this very well. I run the needles through twice and then they dissapear in 1 year but during that time it adds great soil structure. The worms love the easy travel through good composted soil.

Everett, WA(Zone 8a)

>. Pine needles need to be crushed, cut or macerated.

That makes a lot of sense! I think they have a waxy coating to reduce transpiration, especially during the winter.

It always seemed strange to me that we can improve drainage by adding nearly-spherical sand. That "ought to" just pack down tight with all the finer fractions.

To prop up the soil and create voids, shouldn't amendments "have to" have irregular shapes so they tangle with each other and don't pack flat?

At a chemical plant, we packed a kind of distillation tower with "saddles" - doubly-curved, irregularly shaped and with wrinkly fringes, so they couldn't easily pack together.

(Digression into science fiction ....)

I speculate on variations on rock wool, perlite, vermiculite and expanded shale/clay/slate. If you could extrude it or spin it or kiln-fire it so that it formed little I-beams or angle beams, tight helices or tubes, with foamy porous surfaces, wouldn't that be a lot better for drainage,aeration and porosity? Even randomly-kinked plates or rods would stack irregularly.

Maybe the new material would have to be a high fraction of the soil, in order to mostly rest on itself to form an open lattice, instead of just having the interstices fill solid with finer fractions.

Some artifical fibers are spun from mixtures of polymers that shrink differently as they cool or cure. Somehow, that's used to induce them the curl and kink, which gives the threads some properties like "stretch" or "texture".

Maybe co-extruding or co-spinning molten basalt plus shale, or slate plus clay could be made to produce a "twisty" or kinked soil conditioner.

I'm guessing the reason that isn't done is the same reason most things happen or don't happen in the world: money.

Maybe when we start making soil on the moon or from asteroids, it will be worthwhile.


Anne Arundel,, MD(Zone 7b)

Hi Corey--I liked your imaginative soil-particle shapes. Can't wait to buy my bag of miniature I-beam soil conditioner. LOL Meanwhile, you re actually right about sand and fine particles packing down. I think that's whats happening right in my yard. Even though it is easy to dig in, compared to the clay I grew up with, it packs and doesn't aerate well, until I add organic content.

I use pine needles to mulch blueberries, and love them. I wish I had more, readily available around here. I only have one neighbor who lets me rake from one tree.

Everett, WA(Zone 8a)

Pine needles probably are a good shape to "prop the soil up". My childhood experience makes me think they will be very slow to break down, but maybe that's only true when there are so many in one place they keep it too acid, and they aren't chopped or crushed.

>> ... sand and fine particles packing down. I think that's whats happening right in my yard. Even though it is easy to dig in, compared to the clay I grew up with, it packs and doesn't aerate well, until I add organic content.

True! The first benefit of sand is that the clay is easier to break up (I guess "friable").

So many people have scared me with "clay plus sand = concrete" that I always add manure before adding sand.

And I never walk on it once it's in a bed. But I do find that after even a little manure + sand, I can step on it so it packs solid, then still break it up again easily. Also, when a clay crust forms, I can break it up very easily as long as there is sand and some manure added.

With clay + organic + sand, I am still trying to get past :"it holds so much water there's no room for air". Ideally, the fine and medium particles would clump into crumbs, with pores and channels between the crumbs. Some day! I wonder if there is such a thing as "soil glue"?

For aritifical soil additivers, maybe slightly more realistic than "tiny I-beams" would be long tight helices, like curly-fries. If you could make a fiber tightly curly enough, and long enough, it might turn into a soda-straw shape whose interior might provide air channels (until they silted up completely).

And if that curly-fry shape had a hairy and porus surface, the interior channel might be slow to pack solid with silt and clay.

I-beams, hairy curly-fries, soil glue and soda straws! If I produce enough virtual BS, and then pile that up in a virtual compost heap, do you think that will help my soil any?


Anne Arundel,, MD(Zone 7b)


I think organics eventually break down to ' soil glue'. Its been too many years since Soils 101 to remember the details tho.

Everett, WA(Zone 8a)

I've also heard people speculate that "earthworm slime" helps glue soil crumbs together. I don't really know.

A really old soil book spoke of humus breaking down into "humic acids" that leached desirable minerals out of rock grains, solublizing them so root hairs could take them up. Again, I don't know.


Kalispell, MT(Zone 4b)

With my clay I add 5 parts: compost, manure, sawdust, wood fiber, mushroom compost to 1 part clay. And I always do this with dry clay so I can have it mix with the carbonacious mix. Most of my manufactured soils (1 1/2 acre) are raised beds and I continually add compost to keep the little wormies and bugs busy digging.
This is a pile I have composted for over 3 years with manure. It origionally was alfalfa. It is a pile of worms. The majority of it was shredded into the pile before nitrogen added. It is going into my vegetable garden as soil structure and volume for next year.

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Everett, WA(Zone 8a)

>> I add 5 parts: compost, manure, sawdust, wood fiber, mushroom compost to 1 part clay.

That would do it, for structure! You don't have any mineral component except the clay? I guess you must use fertilizer, including micro-nutrients, pretty regularly.

It seems as if it would benefit from at least a little rock dust, but if it works, and clearly it does, then it works.

I'm trying to squeak by with clay:manure :sand :: 3:2:1. Heavy, dude. Wet.
Where needed most, I add more sand until it drains better: maybe 2:2:2.

Your mix is 2.5 times richer than mine.

Don't you have white fungus growing in the soil, with that much sawdust and wood fiber? Or do you pre-compost the wood before putting it into the soil?


Kalispell, MT(Zone 4b)

Clay is the finest soil structure and most available mineral componet of all the soils. Sand is nothing but crystals of silicates no mineral available. I trust clay and the composted materials to keep soils going.

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