Slow-release granular plant food or water-soluble fertilizer will both work. Follow the instructions on the label, but we recommend cutting the dose by half, especially for water-soluble plant food. It is better to be more cautious since White Birds do not do well with too many minerals in their soil. Filtered water is actually better for them than tap water for this same reason. Only fertilize in the spring, summer, and early fall - they slow their growth in the winter naturally and should not be fertilized at that time. When repotting or potting up, you can also refresh the soil to introduce a balanced amount of nutrients. You should repot every 1 to 3 years.