How often should I water a Skimmia japonica 'Rubella'?
That depends where you are and your soil conditions. Since Skimmia japonica is in USDA zone 7-9 and is from low elevation forest in east asia. I would say water it about every three days to once a week when it is established and water when the soil seems kind of dry during hot weather (80F and above). If you have mulch you can water less, since it keeps the ground moist for longer periods