[RichardA]

I noticed yesterday that I only had nettles where I had put compost last year for potatoes whereas elsewhere I had mainly chickweed and groundsel - that reminded me of a note in one of John's books linking weeds to ph.
Does anyone know where I might find a fuller list of weeds that indicate acid or alkaline conditions??
I do use a ph probe meter but think a bit of weed awareness might be a useful early warning.
Thanks
R

[Plot 6B]

Try a google search. I have tried for you and got this.............

http://yourorganicgardeningblog.com/weeds-ph-and-other-soil-indicators/

[Trillium]

Sadly, my weeds are not so choosy. Give them a bit of space and anything will grow, regardless of pH. Only variable is where I've manured or added compost: the richer the soil, the bigger the weeds! 

[Yorkie]

I believe that docks and nettles are a useful indicator of slightly acidic soil.

[savbo]

one problem is that weeds may indicate what the soil was like when they colonised, but not what the soils is like now... I reckon I'd have to do a lot of liming before the horsetail went away

(not a weed as such, but have you ever noticed Reeds growing in hedgerows well after any sign of water has gone?)

[BabbyAnn]

Where the pH of soil is extreme and the ground has not been cultivated, then local flora (weeds) is a good indicator but once you start digging in a plethora of stuff like manure or sand, then it all becomes subjective - you introduce seed from other sources that will try to grow and is not really indicative of the soil conditions unless they start to thrive.  Generally, most soils tend to be shades deviated from neutral pH so a lot of weeds will probably grow anyway unless they were specialists.