The second reason is that the plant needs room to grow, or it will have to compete for nutrients with other plants. “Dividing any herbaceous perennial—like the iris—will prolong the plant ...

No, iris bulbs can stay in the ground over winter. Not only will they be able to survive the winter months, but they’ll also divide as the years go by. Because of this, most experts would advise ...

However, after several years the clumps will run out of steam and die off in the middle, leaving plants that are reluctant to flower. Fortunately it's easy to revive them. Irises spread by ...

These irises usually need to be divided every ... They are easy-growing, long-lived plants that require dividing less often, only when the flowers start to become smaller and fewer in number.

Plants with fleshy roots should be divided with a spade. Make sure the new shoots are visible before dividing. Trim each division with a knife, discarding any old, woody material and damaged growth.