Saturday, August 7, 2010

Luck of the Iris

Never one to seek controversy, I nevertheless must admit that I admire the genus Iris. Among the 250-300 species, there are a wide variety of types to choose from and all, in my opinion, are beautiful. Most are fragrant and many are long lived. They divide easily and come in an astonishing array of colors and seasons of bloom. The name Iris first belonged to the Greek goddess who was the personification of the rainbow and was bestowed on the genus as a reference, no doubt, to the wide variety of hues to be found there.

Certainly, many irises are a challenge to grow in the cool and cloudy Pacific NW. Some gardeners eschew these lovelies because they require heat, drainage and sun and their foliage has a tendency to become tatty and unkempt. So, I will start with the easy going, mostly non-rhizomatous types that are less intransigent.

Iris r. 'Harmony'Dwarf Irises include winter blooming Iris reticulata, I. danfordiae and  hybrids which I covered in a previous post. These bulbous iris are only 4-6” tall, so you must plant them where they may easily seen in the winter and very early spring. Happily, most of the perennials have yet to emerge when these iris bloom in January and February, so although they are small, their bright colors may be seen at a distance. The grassy leaves may continue to grow to 18” after blooming, so site them where you can hide their ripening foliage.

Dutch Irises grow from bulbs and bloom in mid spring. Both Iris xiphium and Iris x hollandica are commonly called Dutch Iris. (Iris xiphium is also called Spanish Iris; this is why I prefer botanical names!) They have long straight stems and lovely blooms so they are frequently used in floral arrangements. Like most iris, they require excellent drainage and prefer full sun but can be grown in part shade. Like most bulbs, the foliage must be left to ripen on the plant and store food in the bulb for next year’s bloom. Don’t remove the foliage until the leaves are yellow. You may lift the clump at that time and separate the bulbs to propagate.

Siberian Iris tolerates a wide range of conditions, thriving in damp and even wet areas. They are most floriferous in full sun, but also bloom in partial shade. They’re not bothered much by iris borer, bacterial soft rot or other iris problems. Their roots are more fibrous than the fleshy rhizomes of bearded iris.

Iris s. 'Butter and Sugar'Known for their graceful appearance, Siberian irises produce arching  grass-like leaves that stay green all summer. In late spring they produce delicate beardless blooms in shades of maroon, white, pink, blue, purple, and yellow. Siberian iris may need to be divided every three or four years to promote abundant blooms. In early fall, cut back the foliage to about 6 inches and divide the clump into sections, each with 5-6 growth points and adequate roots.

These are some of the easiest to grow, so if you are skeptical of the lovely iris, at least give these a try!

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