The Spruce / Jayme Burrows
Some irises have bulbous roots, while others have fibrous root clumps.
And when you propagate bearded iris, it’s this rhizome that is dug up, divided, andreplanted.
What Is a Rhizome?
The Spruce / Jayme Burrows
A rhizome is a thickened section of plant stem that grows underground, similar to a root.
Examples of rhizomatous garden flowers include bearded iris, bamboo, and lily of the valley.
While they can tolerate partial sun, bearded irises will not bloom as prolifically without abundant sunlight.
The Spruce / Meg MacDonald
Prepare the Soil
Iris grows best in well-draining, fertile soil that is neutral to slightly acidic.
Loosen the soil using a tiller or garden fork to a depth of about 12 inches.
An optional step is to thoroughly mix in two to four inches of compost with the soil.
The Spruce / Jayme Burrows
This can be helpful in improving the drainage of dense soils at the same time it improves soil fertility.
Compost is a better choice than bone meal when amending soil in preparation for irises.
(If you have divided a patch of irises, your divided pieces should also have this configuration.)
The Spruce / Jayme Burrows
Look at the rhizomes.
Toss any that are mushy or desiccated.
The fleshy body of the rhizome should rest on the soil mound.
The Spruce / Jayme Burrows
Do not mulch over the planted rhizomes, as this can encourage root rot.
Even if the foliage is less than attractive, leave it in place until it is no longer green.
Regular division also allows you to control borer worms, the most common pest that affects this plant.
The Spruce / Jayme Burrows
The Spruce / Jayme Burrows
The Spruce / Jayme Burrows
