>>1721279>sulfurThat for slow-release, mid-/long-term acidification, for a "quick fix" I found iron(II) sulfate solution helps.
Salavged some camellias that way - had previously planted them in my lime-rich garden soil and wondered why they had shitty growth, didn't know they need low pH. After becoming aware I dug them out and potted them in rhododendron soil, watering with dilute FeSO4 once every couple months (otherwise with rainwater), and now they're flowering for the first time!
