I'm making some potash for my garlic plants, and have a lot left over, so I was wondering if it would be a good idea to share the potash wealth with my turmeric. Any ideas?
Adding potash to the soil your Tumeric is growing in will not hurt it as long as it doesn't make the soil too alkaline. When potash is added to soil it acts as a source of potassium, and also shifts the soil to a higher (more alkaline) pH. Tumeric likes a pH between 6.0 and 7.8.
If soil with potash becomes too alkaline, you can add decomposing organic material (decaying leaves or animal dung), and that will make the soil more acidic. The potassium provided by potash is used by plants for many things but is important for formation of flowers, seeds, and to help a plant winter harden itself (to survive well over the winter).