Pine needle mulch

LG_

It's often said that pine needle mulch is good for acid-loving plants. I mulched a Eucryphia with all my Christmas tree needles and it certainly seemed happy, though that could be a coincidence. Does anyone know if it's specifically pine needles, or would other conifer droppings also work? My yews have a bit of an old needle clear out occasionally, and the leylandii drop bits constantly. Would either be beneficial for my acid-lovers, or would I be wasting my time?

Hostafan1

I'm not sure is the honest answer. 
I've often heard about the needle mulch but I'm not sure it's not a bit of an old wives tale. 
I've not seen any documented experiment which proves any difference of pH due to it.

How deep would the mulch layer have to be to actually change pH? No idea. 

Maybe it's just one of many things said so often that we believe it?

I think mulching is a wonderful idea, maybe it's just the mulch which has helped, rather than it being of needles? I don't know.

Omori

The area under a row of conifers is a lower pH than the rest of my garden.  I've tested it, and anecdotally, the hydrangeas growing there are blue, versus pink in other areas.  These conifers have been there for well over a decade so I'm not sure how long it takes to lower the pH, but it definitely will have an effect over time.

LG_

Thanks Hosta - I think we're on the same page on this one! I have read the stuff about wood chip not actually lowering pH to any significant degree, etc., so the logical conclusion from that must be that needle mulch doesn't either - no? However, I wonder if there's any mileage in it not so much improving the acidity as maintaining it, by not increasing alkalinity? 

However, if we assume that they are beneficial or at least benign (I know it's not a given), my query is really about whether it's conifer droppings in general, or only pine needles?

LG_

Omori said:

The area under a row of conifers is a lower pH than the rest of my garden.  I've tested it, and anecdotally, the hydrangeas growing there are blue, versus pink in other areas.  These conifers have been there for well over a decade so I'm not sure how long it takes to lower the pH, but it definitely will have an effect over time.

Interesting. What was the actual difference when you measured - do you remember? And most pertinently for me - what are the conifers?

Liriodendron

Interesting... I found this:

https://www.gardenmyths.com/pine-needles-acidify-soil/

which backs up your and @Hostafan1 's suspicion that this is an old wives' tale, @LG_.
If it isn't true for pine needles, I suspect it's not true for other conifers either...

Liriodendron

Meant to say - the first of the readers' comments following that article is particularly enlightening.  

Omori

pH in the area under the conifers 5.75.  pH in the rest of the garden, 6.75-7.  The conifers are Leylandii.

LG_

Yes, that first comment was enlightening! Though I wish he/she had proof read it. The article somewhat debunks the rainwater idea as well, though of course the maintenance vs active pH-changing still applies.

This is the stuff I'd read about it: 
https://www.rhs.org.uk/advice/profile?pid=979

Hostafan1

Omori said:

pH in the area under the conifers 5.75.  pH in the rest of the garden, 6.75-7.  The conifers are Leylandii.

I think we'd agree , it's not a HUGE difference for " a decade " of needle drop. 

Omori

No but it's still lower and still enough to affect Hydrangea colouring.  I don't know how quickly over that period of time the pH changed as we've only been here roughly a year, but it isn't a myth that acidic mulch changes the pH.  It's just a question of how long does it take.