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Iris (EYE-ris)

Common Name:  Iris

Light:  - Full sun to part shade

Soil:  Average to loamy, well-drained for bearded Iris; average to rich, moist but well-drained for most others

Moisture:  Average to dry for bearded Iris; average to slightly moist for most others

Blooms:  Early summer, some rebloom in the fall

Zones:  (3) 4 - 9

Looking for Iris plants? Check plant availability at Hallson Gardens by visiting our Iris catalog page


Iris 'Before the Storm'

Iris ensata

Iris louisiana 'Dural White Butterfly'

Iris sibirica 'Caesar's Brother'

Iris Description and Cultural Information

The genus Iris contains many different species and hybrids, grown from either rhizomes or bulbs, and each with different cultural requirements. I won't be covering the bulbous species here since they are not especially hardy and do not rebloom well in the North where they are best grown as annuals.

The Iris bloom has 6 petal segments called the standards (the erect or elevated inner 3 segments) and the falls (the downward or flat outer 3 segments). The bearded iris have a fuzzy "beard" on each fall. There is a huge range of colors including white, pink, red, purple, blue, orange, yellow, copper, brown, and near black.

Iris cristata, crested iris. 4 - 8". The crested iris is a small species with short, broad leaves and sky blue flowers in the spring. Zones 3 - 9.

Iris ensata, Japanese iris. 2 - 3'. The Japanese iris have green, strap-like foliage and flat, beardless 4 - 10" flowers with small standards and wide falls. There are many hybrids in a rainbow of colors and it is usually best to choose from plants that are in bloom. 'Moonlight' has purple petals with white streaks. 'Regal' is deep lavender with white streaks. 'Pink Frost' is creamy white with a pink tint. Zones 4 - 9.

Iris x louisiana, Louisiana iris. 3 - 4'. These iris have narrow leaves and smooth flowers with ribbon-like, drooping standards and broad, flat falls. 'Black Gamecock' is an beautiful hybrid that is dark purple with a narrow band of golden yellow. 'Anne Chowning' has Large, deep red flowers with a yellow signal. Zones 4 - 9.

Iris pallida, sweet iris. 2 - 3'. This iris has stiff fans of gray-green foliage, similar to the bearded hybrids, and fragrant, light-lavender flowers. The foliage stays nice all season long. 'Variegata' has cream variegated foliage. Zones 4 - 8.

Iris pseudacorus, yellow flag iris, yellow water iris. 3 - 4'. These iris have thick, strap like foliage and 2" bright yellow flowers in April and May. 'Variegata' has green and yellow variegated foliage. Zones 4 - 9.

Iris sibirica, Siberian iris. 1 - 3'. Siberian iris have narrow, dark green foliage and 2 - 3" flowers in early summer. The leaves remain attractive all season and plants are seldom bothered by disease or insects. 'Ceasar's Brother' is a popular selection with rich, velvety, deep bluish-purple flowers. 'Butter and Sugar' has white standards and pale yellow falls. 'Baby Sister' has light blue flowers on short plants. 'Ottawa' has rich, dark violet-purple flowers with gold and white markings on the falls. 'Silver Edge' has sky blue flowers with, as it's name suggests, a silver edge. Zones 3 - 9.

Iris bearded hybrids. The bearded iris hybrids are placed into three groups which contain the tall bearded iris (over 28"), the intermediate bearded iris (15 - 28"), and the dwarf bearded iris (under 15"). They all have blue-green, sword shaped foliage and a wide range of colors. Numerous named hybrids exist, to put it mildly, and I'm sure that we will forever be bombarded with new and interesting choices. One feature that is being bred into many new hybrids is the ability to rebloom in a shorter growing season. There have been reblooming bearded iris around for years, but most were only reliable rebloomers in warmer zones. There are now some reliable rebloomers on the market that make a show in the spring and rebloom in late summer, even in cooler areas of the country. 'Immortality' is a pure white reliable rebloomer. 'Champagne Elegance' has near white standards and ruffled champagne colored falls. 'Total Recall' has large flowers with white falls bordered by a bright lemon yellow trim. Zones 3 - 10.

How to Grow:  The culture of iris varies greatly by species, although most tend to perform best in full sun. I. ensata prefers rich, moist soil during its bloom period but needs it well-drained in the winter. I. x louisiana, I. pseudacorus, and I. sibirica are native to rich, wet conditions although they will adapt to drier garden conditions. I. cristata is a woodland species that prefers rich, moist soil in light to partial shade.

The bearded hybrids can be grown in almost any average to rich, sandy loam but must have full sun, excellent drainage, and good air circulation to perform best and prevent rhizome rot and leaf spot diseases. The bearded hybrids are also prone to iris borers. Cut down any diseased foliage and dig up and destroy infested rhizomes. If needed, divide and transplant rhizomes in summer after flowering is complete. Do not wait too late in the year to plant iris as they may not become established enough to bloom the next spring.

Landscape uses:  Iris are invaluable in the spring landscape. Plant them in the border with other iris species, peonies, poppies, painted and shasta daisies, and early blooming daylilies. Plant the water loving species such as I. x louisiana and I. pseudacorus in the bog garden with other moisture loving plants such as ferns, Lobelia, Ligularia, and Rodgersia. Plant the woodland species such as I. cristata along a border in partial shade with hostas, foamflowers (Tiarella), and coral bells (Heuchera).

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