Actually, I do have hands-on experience with using soil sulfur. I recently added it to the soil in my Thai pots. But it's a technique that you shouldn't just jump into unless you can read the results in your plants, and have an accurate ph pen to monitor runoff ph.

I put 1/2 tsp per gallon of pot size in a cup. I add water, and every fifteen minutes or so I take a stick and crush it down and stir, trying to dissolve it to smaller particles. After about an hour of crushing and stirring, I pour it in the pot and water it in well. This helps to keep the large sulfur pellets from burning the roots (via direct and constant contact) so bad they won't uptake nutrients, and allows the sulfur to distribute down into the medium. But this isn't a technique for newbies, and I strongly recommend against other's trying it for anything other than a last resort. With my Thai, the flowering process lasts longer than the buffers in my soil, so additional buffering is necessary.

Might be a good idea next time you have issues, to check in here (ask for advice) before you do anything like this. Hopefully they'll be fine, but keep an eye on 'em and post pix in the next day or so. :thumbsup:
Rusty Trichome Reviewed by Rusty Trichome on . Fixing soil grow PH level I'm a newb and in 3rd week of seedling (NL) grow in 1 gallon pots each about 3" tall with multiple leaf sets, Leaves turning yellow. Followed threads on this subject and checked PH level in soil two ways: 1st with probe and reading was above 7 and 2nd test with, test tube and result was same reading as per color chart of above 7 maybe close to 8 ... Holy !!! WOW !!! Too High from what I am reading/learning. Anyhow I added 2tsp. of sulfur granuals to each pot and mix in and then watered. Hope Rating: 5