Significance

• Irises will perform best if you dig them up and replant them every three to five years for rejuvenation and better flowering. Undertake this task after the flowering season ends; otherwise, the root disruption is at the expense of flowers that year.
  
  

Time Frame

• The general rule for optimal separation of iris roots and replanting is from midsummer to mid-fall. Dig and replant them two to three months before the expected fall frost. In much of the United States, that means from early August to mid-October.
  
  

Considerations

• If flowering has ending, gardeners can dig and separate iris rhizomes in July if an emergency or other deadline lingers. If possible, the latter half of July is better. In cold winter regions with short growing seasons, a July time frame is better than in areas with long, hot summers. Dig and separate beardless iris types in August or September.