You can do it!

Buying the plants

Irises are usually available in the garden centers and catalogs by early August. “Buy from someone you know,” Laura Buelow recommends whether it’s from a local nursery or from a catalog. Buelow doesn’t like the iris she finds at the mass merchandisers because they are often already dried out by the time they reach the store shelves. “Sometimes they are mislabeled (with the wrong name),” she says. For a serious iris collector, that can be a major problem.

Look for firm, white roots with no nicks or dings and are not dried out; that have a healthy set of smaller roots coming off the main rhizome, and a healthy set of leaves growing from one end.

Planting and dividing

The biggest challenge to growing iris is planting and dividing them at the right time in the year, late July through late August. The plants bloom in early June using food stored in the rhizome from the previous summer. After they finish blooming, the rhizome must have a chance to rest and re-build its reserves – about six weeks, which takes the plants to the middle of July.

“The biggest mistake people make in planting iris is to plant them too deep,” says Buelow. Dig a hole 6-inches deep and twice as wide as the rhizome is long. Mound up a hill of soil in the middle of the hole and set the rhizome on it so that the top is at or slightly above the soil surface. Spread the smaller roots out and down a little before filling the dirt into the hole. If rhizomes are planted by the end of August, they will have enough time to set their roots and reduce the chances of frost heaving them out of the ground over the winter.

Bearded iris clumps need to be divided every three to four years to continue to flower at their peak. Buelow usually replants the largest rhizomes from the outer edges of the clump to produce the best flowers.

Japanese iris rhizomes should be planted 2 to 3 inches deep in a depression which will help catch water. Fill the depression with organic mulch annually. It takes two to three years for the clump to reach full bloom. They need to be divided in the spring every three to four years when the clump has formed a solid ring with a bare center. Divided clumps need to be planted in a different location because Japanese researchers think the plants secrete something in the soil that eventually reduces the vigor of the clump over time.

Siberian Iris

Plant Siberian Iris with the top of the rhizome 1 to 2 inches below the surface, on a mound of dirt in the hole dug for it to ensure that there is not an air pocket beneath it. The roots should be spread downward over mound and then replace the soil, and water well. They often do not bloom the first year after replanting.