Sulphur chips as slow release substrate acidifier?

[MatDz]

Does anyone use sulphur chips to acidify their potting substrate? They seem really good, with the slow "release" one just mixes them in and perhaps checks the pH once in a while.

Sample listing: https://elixirgardensupplies.co.uk/prod ... ertilizer/

[Cidermanrolls]

I use sulphur in my cricket grounds work as a way to reduce the pH of our local natural soils, which sit on limestone. It does appear to work, though slowly over several years, but I’d be concerned about its use in pot-culture.
Across a 1500m^2 cricket square I will apply 25kg each winter. That’s about 17g per square meter. Any more and you risk toxic effects. The advice is to apply in the cold seasons, presumably to allow breakdown and dispersal of the sulphur prills before the oxidation takes place in warmer weather.
Calculate the application rate through to a 2.5” square pot and you are looking at <0.2g per pot. I’ve never weighed the individual prills that I use in cricket, but I’m guessing that’s one to two prills per pot.
Then you come to the way the sulphur breaks down to sulphuric acid - it needs moisture, air and bacteria as I understand it. Is a cactus collection the right environment? Will you get enough uniformity of sulphur distribution to avoid local hot spots?
Why not use something like citric acid in your water? You’ll get uniform dispersion and control. And no need to rely on oxidation to get the acidity. And citric acid is cheap as chips.

[Nick]

The rate of change of soil pH will depend on the physical form of the sulphur as well as the amount. Surface area of a given weight of “chips” will be much reduced compared to that of powdered “flowers of sulphur” type products - the latter may give a relatively short lived spike

[MatDz]

All good points, thanks! I was hoping to "engineer" a solution that would give a fairly stable pH reduction over longer period so that I don't have to remember to add things to the water while watering. This "solution" is probably not worth the effort...

[gerald]

It will work - over time - but why not just ensure your potting mix is the correct pH to start with?

[MatDz]

It will work - over time - but why not just ensure your potting mix is the correct pH to start with?

Because there seems to be no low pH, low or inorganic (and ideally peat free) available in retail.

[gerald]

Maybe not locally but there are many types of peat-free pH4 ericaceous composts available online