How to Fertilize iris 'Red Ember'?
Diluted iris feed every three to four weeks during spring bloom

iris 'Red Ember' · Iris 'Red Ember'
Grow in any moderately fertile, neutral to alkaline, well drained soil in full sun. Plant bulbs at twice their height in late summer or early autumn and feed with a high potash fertiliser after flowering. See bulb iris cultivation for more information
Diluted iris feed every three to four weeks during spring bloom