Will Irises Multiply

Irises multiply fairly quickly and when the plants become overcrowded they produce fewer of their lovely blooms. It is very easy to divide iris plants to rejuvenate them, and for the best display, bearded irises should be divided every three to four years.

Do irises spread?

Bearded Irises Grow from Rhizomes Such plants also spread by rhizomes, and irises are no exception. While some rhizomatous plants, like bamboo, spread rapidly and even invasively, the iris spreads fairly gradually—one of its main virtues for gardeners. But, as iris rhizomes spread, they become crowded.

How fast do iris bulbs multiply?

They are very hardy and deer and pest resistant. Irises need about two months of rest after blooming before they can be divided in late July through late August. This allows them time to store up reserves for next year. Clumps usually need dividing every four or five years to keep them blooming profusely.