Q: Can I use a teaspoon of wood ash from the fireplace to fertilize my house plants?
A: A teaspoon probably wouldn’t hurt anything but ashes don’t contain anything useful to a houseplant. All that ashes are good for is to counteract soil acidity. In general, ashes are too alkaline to add to houseplant soil. Use fireplace ashes on your lawn instead. The rule of thumb is 20 lb. per 1000 sq. ft. per year, spreading 10 lb. in winter and another 10 lb. in late spring