Growing Beautiful Iris

By Patricia Diaz, from the June 2005 Newsletter

Right now is the perfect time of year to visit local iris gardens and pick your favorites for fall planting. You can browse down the rows of gorgeous irises, then place your order for your rhizomes. There are two great iris gardens close by – Corriehill Iris Gardens, located at 1045 Frink Rd., Moscow, and Iris Test Garden, located at 1102 Endicott-St. John Rd. in St. John, (509) 648-3873, www.iristg.com. To visit Corriehill Iris Gardens when the flowers are in bloom, call to inquire at (208) 882-1007. Iris Test Garden is open the months of May and June.

The tall bearded iris, considered by many to be the most stunning of all the iris varieties, grow well in our climate and multiply nicely. Every season more and more varieties are produced – there are literally hundreds of them from which to choose. Of course, the newer varieties cost more so if cost is an issue, you might want to pick some of the older varieties. All colors abound except true rose red and lime green, although there is a pale chartreuse available. There are banded ones, bicolor, variegated, striped, and speckled.

The term “beard” refers to the part that’s centered on the falls, or the outer petals. It’s the part that looks sort of like a fuzzy caterpillar and they can be of contrasting color, shaped like spoons or flounces. Standards are the “fluffy” part that stands up from the falls and can be of contrasting color or the same as the falls. Scents vary in intensity and character.

Bearded iris flowers come from rhizomes, not bulbs. Rhizomes are actually swollen underground stems that look like tubers. These produce the fan of leaves that will then produce flowers. Plant rhizomes with the fans all parallel and face them toward full sun. They need at least a half-day of sun. They like good drainage and planting irises on a slope or in raised beds is a good idea. You might want to add coarse sand or humus to improve drainage or add gypsum if you have heavy clay soil. Plant the rhizomes so that the tops are exposed and the roots spread out. Firm around each rhizome and water to settle the soil. A common mistake is to plant the iris too deeply. They like spacing that is 12-24” apart, but you can plant closely for effect. You will have to thin them more often. If it’s a mild summer, you can plant from July through fall or wait until September if it’s a hot summer.

Irrigate your irises when the fans start growing in early spring until about six weeks after they finish blooming. If it’s hot, water about once a week if soil is light or every other week if the soil is heavy. Once irises are established, they usually don’t need watering unless it’s quite arid. Over watering can lead to soft rot.

A complete fertilizer, bone meal, or superphosphate is recommended when growth starts in the spring. Avoid nitrogen as it encourages rot problems.

Every three to four years you’ll need to divide or thin your iris clumps. If they become too crowded, they no longer bloom. The best time to divide them is six to eight weeks after they’ve finished flowering or should have flowered. Cut back the leaves so they’re six inches tall, creating a curved, fan shape with the remaining foliage. This makes them easier to handle, reduces water loss, and makes their appearance better. Use a sharp knife to cut the rhizomes into smaller pieces. You need one fan of leaves per division. Discard any rhizomes that appear damaged or insect-infested. Replant the healthy rhizomes five inches apart in a newly prepared bed, just below the surface or half buried.

After blooming, the bloom stems should be cut off close to the ground. But don’t disturb the leaves – only remove brown or diseased leaves. I have several beautiful irises in my garden but couldn’t tell you my favorite – they’re all beautiful! Enjoy!

Pat Diaz gardens on the eastern edge of the Palouse. She’s already got her Oregon Spring tomatoes sheltered on the deck, the forsythia newly planted, as well as a riot of spring blossoms. What a wonderful time of year!

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