My soil pH was running high at 7.5 almost 8, so I got some sulfur. I added about a tablespoon per plant. My pH dropped to 6.5 briefly the other day and is not back to 7. I know bacteria need some time to break down the sulfur in order to make the soil acidic, but how long does that take? Since it went down after a day or two then went back up, should I apply more or wait? Its been about a week now.
It can take up to a year for the soil bacteria to fully convert the powdered Sulfur into it's acid form. Faster the warmer the soil is. Usually a spring application after the ground thaws for large outside areas is suitable for the summer planting. I use powdered Sulfur in my soil since my tap water is 8.5PH and never changes. Hot and dry here so I use a lot of water and it eventually showed in my Cannabis plants. I add a tablespoon to each 3 cubic foot planting hole 4 times per year and it's kept the plants nice and green for 4 years and 4 sets of plants per year. So Calif is warm enough I can flower outside year round. Never freezes here near the beach. BNW
Good to know. Thanks. What would you recommend for a quick fix? Is the powder sulfur quicker than elemental sulfer? Is Iron sulfate or Magnesium sulfate faster?
Both the iron and mag sulfate claim to be somewhat faster then the straight Sulfur. Actually Aluminum sulfate is fastest but with Cannabis I'd pass on that one given Cannabis's ability to absorb metals. For right now lowering of soil PH the recommendation is sulfuric acid but that calls for extreme care in handling and application. Powdered or granular sulfur is the route I'd go and it'll do the job fast enough. It took my grow well into the second year before all that high PH tap water really started to show it's face in the plants. BNW
Soil tends to naturally buffer the PH more then other grow mediums. Unless your seeing actual high PH damage I wouldn't push my water down past say 6.0. Grow long enough and you start to discard a long list of so called necessary steps and just let things run. I went from a list of 15 soil amendments to just 2. Sulfur and Chicken Manure. I add them between each flowering plant when I harvest and the hole is empty for a day or 2. Haven't tested my water or soil in about 4 years and 16 harvests and things keep ticking along. BNW