Are pine needles to acidic to use as a mulch (flower or veggie gardens)? I know they break down pretty slowly. Thanks.

I have a lot of pine trees in my yard. I let the needles stay where they fall in my mixed borders and it hasn't been a problem, although we've only been here three years. In the areas where I have purposely mulched with a couple inches of needles, the worms, etc really liked it as long as it didn't dry out too much.

All raw woody products are acidic, from sawdust to bark, to pine nedeles. However in a compost pile all acidic and alkalinic organic materials get digested and neutralized, so that the pH of mature compost is always near neutral.

The only way that uncomposed acidic woody materials can alter soil pH, is if it is mixed into the topsoil. This is a no-no! Never do it! Only use fully mature compost in the soil. That way the soil microbes can totally focus on feeding nutrients to plant roots, in stead of wasting time breaking down and digesting organic matter into humus.

If the underlying topsoil is rich in mature compost or humus, and has sufficient nitrogen in the soil to feed soil microbes, then you can use any form of raw, uncomposted woody mulches, on top of the soil, and it will never create an acidic soil pH issue, nor create a temporary nitrogen deficiency for local plant roots in the soil.

No they are not, when used as mulch. It is an old wives tale, totally unsupported by any research, that pine needles, or oak leaves, will change the soils pH and reported in Organic Gardening Magazine way back in the 1970's, but the myth hangs on. Maybe, possibly, if you added 10 tons of them it could have some affect on your soils pH.

Pine needles are my mulch of choice in the vegetable garden.

Cedar Creek, Tx dirt is on the alkaline side. I'll take all the pine needles I can get.

It is a myth that pine needles, or oak leaves, will change your soils pH. There simply is no research to support that conclusion while there is lots of research out there to show that they have no affect on soil pH. Maybe, possibly if you put tons of them into your soil at once there might be a slight shift, temporarily, downward.

Like Captain Compost said, when big stuff (branches, pine needles, woody stems) gets into the soil it will compete for the nitrogen with the little roots of your plant below it, which is why we compost the big stuff until it is unidentifiable. Then it's broken down and everything is available to the little roots of your plant.

Vegetables have such a short time to produce, it doesn't seem advantageous to put the Big Stuff around them, because they need it NOW, not many months from now. So pine needles are a great mulch for blocking light if put on thickly enough, and keeping weeds down, and they verrrrryyyy slowwwwwly break down. To get the quickest benefit from pine needles, compost them with everything else where you get a good balance of ingredients, and add that to the soil.

In nature, it's actually the leaking pine tar from the tree and dead branches that is causing the acidity under pine trees, and what is sometimes considered "toxic" conditions. Obviously not toxic for pine trees, but there are petroleum derivatives in pine tar.

It's also been found that the isocupressic acid in some pine needles causes abortions in cattle, horses and goats, or significantly weakened offspring. And while that doesn't concern a lot of gardeners, people who are living off the land by growing their own vegetables and having farm animals need to be aware that it's not good for pregnant animals that might graze the needles.

Thank you all, for your help - very informative!

If your just looking for a way to use up those pine needles,I lay them down as a mulch on my garden path.They last ages and look nice.They get a bit slippy when wet so be carefull.
Mavis

Mavis, that's a really good idea, and it would work well on the paths the mandala design of planting. I think I'll try some of mine that way too!