The white that appears on the moss of your kokedama because of the following reasons:
1. Build up of minerals in the type of water such as tap and/or filtered water.
2. Not drained sufficiently after submerging.
3. Lack of airflow for ventilation, the moss retains humidity.
Our recommendations are the following:
1. Brush the affected area gently.
2. Mix 1 part water 1 part hydrogen peroxide.
3. Spray the affected area.
Repeat this process every time the white appears. Another suggestion to avoid the white appearing is every time you submerge the Kokedama, let it drain for 20 min and squeeze gently, So the moss doesn’t stay as damp. Also, airflow will prevent this from happening.