How to Fertilize Siberian iris 'Tropic Night'?
Diluted iris feed every three to four weeks during spring bloom

Siberian iris 'Tropic Night' · Iris 'Tropic Night'
This cultivar is suited for cultivation in both herbaceous borders and informal pond-side settings. Grow in moist but well-drained neutral to slightly acid loam in full sun or partial shade
Diluted iris feed every three to four weeks during spring bloom