Bearded iris grows from a rhizome, another form of underground stem. Bearded iris stops blooming if it gets too crowded. Use a sharp spade or shovel to lift the patch of irises to be divided.

Answer: Bearded iris are the largest in size. You should be able to see the tops of the rhizomes (underground fleshy stem) all summer, so do not mulch, or these will rot.

The OregonianJapanese iris Rhizomatous iris -- the kind that grows from rhizomes -- includes Siberian, Japanese and bearded iris. (Other types of iris grow from bulbs and have different care ...

Ask the Gardener’s Carol Stocker gets to the root of the problem with bearded iris, offers advice on biennials, and lists what you should do in the garden this week.

Q: We have had a patch of iris for about 10 years. You can imagine how thick that patch has become, since we have never thinned them out. I have read that they should be dug up and divided in July … ...

Divide irises when they are dormant in midsummer. After blooming in spring, plants slowly move into a dormant period that lasts for about six weeks during the warmest part of summer. July and August ...

While July gardening chores revolve around watering, weeding, deadheading and helping plants through the heat, those chores might include transplanting bearded iris and watching for powdery mildew on ...

Award-winning garden writer Carol Stocker takes readers' questions on irises and saving monarch butterflies. Get more expert advice at realestate.boston.com.