Wood ash can be a valuable addition to outdoor plant box soil when used correctly. Rich in potassium, calcium, and trace minerals, it acts as a natural fertilizer and pH balancer. However, moderation is key—excessive ash can raise soil alkalinity, harming acid-loving plants.

To use wood ash safely, sprinkle a thin layer (no more than 1/4 inch) over the soil and mix it in lightly. Avoid applying near seedlings or plants like blueberries that thrive in acidic conditions. Always use untreated wood ash, free from chemicals or additives.

Benefits include improved nutrient availability and pest deterrence, but test your soil pH first to prevent imbalances. Pair wood ash with compost for optimal results in your outdoor plant boxes.