The Bearded Iris is, for much of the country, a reminder of Memorial Day, as this is usually the time of peak bloom for this showy group of perennials. I enjoy these beauties for their easy care, their tough constitution and their large, colorful flowers in a huge array of solid and bi-colored combinations.
Bearded Iris are very dependable in the garden when you provide them with:
plenty of sun
a well-drained planting site
well-amended soil (go heavy on the compost and soft rock phosphate as Iris are heavy “feeders”)
Fall is an excellent time to plant Iris, so you can enjoy their flowers next spring. But don’t feel you need to isolate Iris or plant them apart from the other flowers in your garden as is often done. (Roses often suffer this same fate.) Iris mingles nicely with other perennials, especially because their attractive, sword-shaped leaves provide a nice contrast with the other foliage, much like a thick bladed ornamental grass might do. And the wide range of flower colors allows them to be inter-planted with other perennials to provide a rainbow of complementary flower colors.
The big news about Bearded Iris is that many new varieties are “re-bloomers” flowering in late spring and re-blooming in August (with prompt deadheading of the old flower spikes). This has reinvigorated interest in the Bearded Iris and kept the breeders busy expanding their offerings.
In terms of maintenance, the best time to divide your Iris clumps is in August. When they stop blooming or the flowers are sparse, this is an indication that they are crowded and the soil is low in nutrients and needs to be enriched.
Just dig the plants out of the ground, shake off the soil and cut the rhizomes (fleshy roots) into pieces with a sharp clean garden knife. Be sure to include a fan or two of leaves on each piece of rhizome. If you have some dusting sulfur, dip the cut ends into it and let the rhizomes dry for a day or two in the shade so the cuts callus over.
Before you replant the divisions, dig a 3 to 4 inch thick layer of compost and a few handfuls of natural soft rock phosphate and Yum Yum Mix into the top 8-10” of the soil. Plant so that the shoulders of the rhizomes are just above the surface of the soil. Don’t plant them too deep.
One of my favorite Bearded Iris would have to be Iris pallida ‘Variegata’. The soft purple flowers are wonderfully fragrant and the boldly striped green and white leaves enliven any bed where they are planted giving the plant season-long garden interest.