[omits]

I have one of those push in meters (two legs). I tried it on a sack of ericaceous compost and it read just over 6. I thought it should be 5.5 or a bit less. Anyway I have some Blueberry plants and neither of them did very well last year and I want to perk them up a bit. The two of them are planted in a bed. I have put some of that Ericaceous around them but did that last year and didn't seem to help much (readings recently were about 6). Their buds are just coming on–I am in Dorset. I have some horse manure and some well rotted own veg compost. How can I give them a proper chance this summer and get the PH to around 5? many thanks.

[Hampshire Hog]

According to RHS you need to add sulphur chips if your soil isn’t acidic enough which sounds like your situation. Good reminder I must dig out my PH meter!!

[Plot 1 Problems]

My soil is naturally alkaline so I add Iron Sulphate to the beds (apart from the brassica one) each year.

[Subversive_plot]

The following link provides information on the accuracy of inexpensive soil pH meters or inexpensive test kits:
https://www.google.com/url?q=https://www.gardenmyths.com/soil-ph-testers-accurate/&sa=U&ved=2ahUKEwiH-OPrjcX9AhWoPUQIHbOsAVUQFnoECAUQAg&usg=AOvVaw285STQsgl534f38Lx8YxWg

It includes a link regarding changing soil pH, including information on soil buffer pH, which is the degree to which soil resists pH change, due to buffer capacity.  A soil lab is your best bet for assessing soil and what to do to change the pH.

[omits]

According to RHS you need to add sulphur chips ...

Is that the same as Sulphate of Ammonia from B&Q? Thanks.

[JayG]

No it's not the same - my sulphur chips were made by Chempak, and don't seem to be widely available in shops, although I did manage to buy mine from a local garden centre rather than online.
They take a long time to break down and take effect, which isn't necessarily a bad thing.

Ammonium sulphate will actually lower the pH too, although it's generally used as a high nitrogen fertiliser. Being highly soluble the effect on pH is likely to be relatively short-lived.

Impossible to know whether your pH probe is giving you accurate results, but as Subversive Plot suggests, the odds are it isn't. A chemical (indicator dye) pH soil test kit is a much better bet.

[omits]

...

OK, thanks. I have two Blueberry plants which don't do too well. I've bought some of https://www.amazon.co.uk/dp/B01NCZI7CN/ref=pe_27063361_485629781_TE_item. But also thinking of replanting the other and need to know what to put in the soils around it. Soil genrally on my allotment is around 7.

[JayG]

The feed you mention is of course suitable for ericaceous plants, but won't tackle the problem of the soil pH being too high.

Best to replant in a hole filled with ericaceous compost rather than just mulching with it, which I'm assuming from your first post is what you did.

Given your soil type, over time the pH will tend to rise again, which is where the sulphur chips come into play, although acidic mulches can help too.

[Harry998]

Just to reiterate what subversive_plot said cheap ph meters are dangerously inaccurate. A decent direct measuring meter from some one like hanna instruments will set you back £100 plus and needs a fair bit of love to keep it accurate.
For general curiosity lab tests are the best way forwards, for anything ericaceous it's normally cheaper to just back fill the hole with ericaceous compost and give it the recommended dose of sulphur each year.

Also worth nothing most sulphur forms needs to be broken down by soil bacteria to effect the pH and it can take months so best kept on top of