How to Propagate iris 'Carnival Time'?
Dividing irises should be carried out every 3-5 years from midsummer to early autumn, see dividing irises

iris 'Carnival Time' · Iris 'Carnival Time'
Grow in well-drained, fertile, neutral to slightly acidic soil in full sun. Do not cover the rhizomes with mulch, or allow other plants to shade them. See also bearded iris cultivation
Dividing irises should be carried out every 3-5 years from midsummer to early autumn, see dividing irises