How Does Thiamine Improve Rooting?
A study 1 on teak cloning found that combining Indole Butyric Acid with Thiamine (vitamin B-1) improved cloning success. In this study a 1000 PPM IBA and 3800 PPM thiamine was used. Keep in mind that this was effective on one type of plant and is not an absolute. It may be that a ratio of Thiamine 3.8 to Indole Butyric acid is a good idea of you are having problems with cloning.