In My Garden Blog
New England
June 27, 2002
By
Suzanne DeJohn,
Cambridge, VT
There are three types of iris in this early summer bouquet: large bearded, smaller Siberian, and yellow flag.
Amazing Iris
My first attempt at growing iris was a sad failure. I bought a container-grown plant and, taking my cues from other iris I had observed, stuck it in a mucky wet spot. After all, those cheery yellow iris growing in the drainage ditch across the street seemed to thrive in standing water! Unfortunately, I was planting a bearded iris, a plant that demands excellent drainage.
In many cases, you can make assumptions about the growing habits or environmental requirements of a plant by looking at its close relatives. Most willows prefer moist soils; most mint-family plants readily multiply. Not so with iris. Different types have wildly differing requirements, especially when it comes to water.
Bulb or Perennial?
I should have known something was amiss when I saw iris listed under both bulb and perennial catalog headings. So which are they? Like another strange amalgam, the platypus (that duck-billed, egg-laying mammal), iris don't fall neatly into a single category. There are more than 200 species of iris; some are true bulbs, others grow from bulblike, but botanically distinct, fleshy rhizomes. (One rare iris has neither bulbs nor rhizomes, but instead produces fibrous roots.) Rhizome-bearing iris are sometimes listed under bulbs in catalogs, because they resemble bulbs and are planted in late summer or early fall, along with other spring-blooming bulbs.
Plants that have been cultivated as long as iris have - thousands of years - often have complex and convoluted classification systems. We won't try to unravel them all here; instead, let's look at some of the most common iris groups.
Bearded Iris
Bearded iris are easy to identify: just look for the "beard" a furry or fuzzy patch along the down-turned petals (the "falls"). The plants bloom in late spring or early summer; some varieties, known as "re-blooming" iris, will bloom again in the fall.
Bearded iris are further divided into categories depending on their height. They range from dwarf varieties just 6 inches in height to tall bearded iris that can reach a height of 4 feet or more. Check plant descriptions carefully to ensure that the height of the variety you choose is appropriate relative to other plants in the bed.
Bearded iris demand excellent drainage; the rhizomes will rot in saturated soils. They prefer a rich but well-drained, pH-neutral soil in full sun, but are relatively adaptable to most conditions - except wet soils.
Bearded iris are sold as bare-root divisions or potted plants. Each division consists of a thickened rhizome with a few fat roots and a trimmed fan of leaves attached. Counter to intuition (at least to my intuition) the rhizome should be set horizontally so that the top surface of the rhizome peeks above the soil. Buried too deeply, the rhizome may rot.
Beardless Iris
To determine if an iris is beardless, just look for the beard! Easy, right? Beyond that, however, classification of beardless iris is quite complex, so we'll just look at a few of the more common types.
Siberian iris (Iris siberica). Although the individual flowers of Siberian iris are smaller than those of the tall bearded varieties, they are borne in greater profusion above clumps of attractive, swordlike leaves. Siberian iris produce small rhizomes, but also have extensive fibrous roots. They are usually sold in containers rather than bare-root; if you divide your plants, set the rhizomes about 2 inches deep. Many plants sold as Siberian iris are actually hybrids of I. siberica and I. sanguinea.
Japanese iris (Iris ensata, formerly I. kaempferi). The petals on these iris spread horizontally, as opposed to the upright petals and falls of other types. The flowers are large - up to 6 inches across - and borne on tall, erect stems. The rhizome is slender with many fibrous roots, and should be planted about 2 inches below the soil surface. Japanese iris are somewhat more exacting in their requirements -- moist, acidic soils and winter protection in cold climates -- but they are relatively easy to grow if those needs are met.
Flag. Yellow flag, Iris pseudacorus, and blue flag, Iris versicolor, grow to a height of 4 to 6 feet and thrive in damp to wet soils -- even shallow standing water -- making them good choices for pondside areas. They can even become weedy in favorable locations.
Dutch iris. Hybrids of the Spanish iris (I. xiphium), bulb-forming Dutch iris produce striking flowers atop sturdy stems, making them popular cut flowers. The bulbs should be planted about 4 inches deep in the fall, along with other spring-flowering bulbs.
Crested Iris
Neither bearded nor beardless, crested iris (Iris cristata) are in a group by themselves, and are characterized by a raised ridge (or crest) along the lower petals (where the "beard" would be if they were bearded irises). In the wild, crested iris are most often found along lightly shaded stream banks - cool, damp, but not overly wet soil is preferred. Small in stature - just 4" tall - the flowers are nonetheless exquisitely formed, and a carpet of these late-spring-bloomers is a sight to behold.
Iris, the Goddess of the Rainbow
In Greek mythology, Iris was the messenger of the gods to humankind. Her name means "rainbow," and she was revered for her role in lifting water from lakes to the clouds, ultimately bringing rain to farmland. Consider adding a variety of iris to your gardens -- perhaps in honor of the goddess, in the hopes of easing the current drought, or just because they are wonderful plants!
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