Bill, yes it's slow but it does happen eventually. Case in point; my hydrangea which was a hot pink when it was planted 6 years ago but now is slowly turning blue due to pine needles as mulch.

Well the only things that I try to acidify at this juncture are my blueberries. They will get their fall dose next week. I look forward to next spring to see if I get increased berry production like I did this year.
This year I got about two and a half cups. They were oh so delicious!

BigBill said:If pine needles "break down slowly", how can they effectively acidify the soil?
I agree that they look pretty but there are better ways.

MYTH: Ponderosa pine needles make the soil more acidic (low pH).

REALITY: The notion that pine needles change the soil pH so that nothing will grow or that it will damage plants has been out there for years. The truth is pine needles do not make the soil more acidic.

https://extension.oregonstate....

I have evergreen , Spruce, needles under my Spruce trees, very thick, ditto for Pine needles under my Black Pine.

Weeds will grow in, on and under them but are much easier to remove, unless, you let them turn into a dirt mat and the weeds root into the bottom of that mat, especially Quack Grass.
Then tisn't so easy.

RpR said:
MYTH: Ponderosa pine needles make the soil more acidic (low pH).

REALITY: The notion that pine needles change the soil pH so that nothing will grow or that it will damage plants has been out there for years. The truth is pine needles do not make the soil more acidic.

https://extension.oregonstate....

Thank you! I was on my way to my state ext. page to find a link to post as well!

Here are inert ceramic balls, acid and alkali resistant.

http://m.ksourceltd.com/cerami...

or



Extremely durable, lightweight and cheap.

I could make a 10 inch bed with it and no weed would creep up.

Thoughts ?

The easiest and cheapest way to mulch for the season is to put down a layer of newspaper or cardboard. (Check your grocery store. Mine lets me have as much as I want.) cover that with mulch. The cardboard and newspaper blocks the weeds and the mulch just makes it look better.

Mine is usually broken down after a season so I dig it under and start with a new layer. Quick, cheap, and. effective.

Now I had never heard of this dude , or dudette, before and I found this only while seeing what some experts think of the shebang of corrugated cardboard in gardening but I thought I would put it here anyway.
Now I think Number 2 is a total load of bollocks but it shows what some "experts" are thinking.

1- http://gardenprofessors.com/wh...

2- http://gardenprofessors.com/is...

3- http://gardenprofessors.com/sh...

4- http://gardenprofessors.com/pe...

5- http://gardenprofessors.com/th...

RpR, thanks for posting those

Gosh, there's no doubt about how Dr Chalker-Scott feels about sheet mulching!

I've actually never used cardboard or newspaper as mulch, but I know a lot of gardeners do. I'm also a fan of Linda Chalker-Scott and find her to be science-based and no-nonsense. In this case, all of the examples she gives are in dry situations, except where she mentions vegetable gardens, and in that case she approves. So maybe the key to retaining soil health while using cardboard as mulch is keeping it moist so water permeates—but then of course it will break down and no longer be mulch. I can see how it would be similar to using dreaded plastic sheeting in a dry environment, but if I recall the original question of this thread, it was about mulching blueberries, which would need to be watered regularly.

If you're interested in seeing some of Linda Chalker-Scott's other articles, here's a site.

https://puyallup.wsu.edu/lcs/

Frederick. You seem determined, you just may have to try and let us know.

I read an article back in the 90's that said that vermiculite, and to a lesser extent Perlite, retained minerals and could become toxic over time. Prompted by this discussion, I have been looking to find that article to no avail. The gist of the article from the 90's was that either absorbs minerals from the soil and water. The minerals, especially calcium and phosphorus build up in the outer layers of the perlite/ vermiculite pieces. This is especially true of the pieces near the soil surface. They can become toxic to plants over time, and can harm the base of the plants, and surface roots.
However, I did find this:
https://www.sciencedirect.com/...
The gist of this one is that vermiculite can release aluminum into the soil in an acidic environment. Aluminum is very toxic to plants. Because of this, it would not be a good addition to the soil, or mulch on the top of the soil, for blueberries. Blueberries like a low pH. Perlite might be OK as a mulch, but it would wash away given the first thunderstorm.
I stand by my recommendation of newspaper covered with pine bark nuggets as being the best way to mulch blueberry bushes.

I don't understand why perilite would be used.
Can anyone enlighten me?
Thank you.

Thanks for getting back to us, Greg. Although aluminum is easily toxic to blueberries, not so much for the better part of the plant kingdom. Of course, any exorbitant excess of nearly any micro nutrient can be problematic, including aluminum. Although the link you provided didn't include any info on vermiculite (oops!), it did set me on an easy venture that substantiates you claim. I was disappointed that I could not find even a hint of what that breaking point of low pH would be. But I am confident that for growing blueberries, the impact would be significantly detrimental.

Tisha said:I don't understand why perilite would be used.
Can anyone enlighten me? Thank you.

So far, none of the respondents to the original question understand either, hence this discussion.


@frederick11, What about pecan shells? They can be piled thickly and still allow water & air to permeate, take quite a long time to break down, are easily replenished with a top layer, plus they look nice. Probably moderate weed-suppression, depending on thickness, but no worse than perlite or clay balls, certainly.