How to Grow Perennial Iris Plants
Plant Profile - Using, Maintaining and Selecting Iris Bulbs
Nov 21, 2008
Iris flowers have been a favorite part of many garden landscapes for centuries, divisions passed from friend to friend. Here are some iris bulbs worth growing, as well as information for which areas of the garden to plant them in.
Cultivation and Botanical Information about Iris Bulbs
Botanical and Common Name: Irises are call by their scientific name.
Plant Category: The Iris flower is a bulbous or rhizomatic perennial plant.
Bloom Time and Color: The iris group is large and has irises that bloom in winter, some that bloom in the spring and others that will flower in the summer. The roots of all of them are fleshy with some more rhizomatous and other iris that look more like true bulbs.
Foliage: Iris flowers have thin, upright foliage that adds a vertical accent to any container garden, bulb garden or mixed border planting. The grass-like foliage is thicker than most ornamental grass blades but still adds that movement to a landscape when planted in a mass.
Growth Habit and Dimensions: Irises vary in size from the diminutive, bulbous Reticulated Iris (I. reticulata), which grows only 4 to 6 inches tall, all the way up to the Tall-Bearded Iris (I. germanica) and Flag Iris (I. pseudacorus) which grow 4 to 5 feet tall. All iris plants have an upright growth habit with bold-colored flowers on tall stalks.
Preferred Conditions: Various Iris bulbs do best in different areas of the landscape, allowing gardeners to use iris flowers in almost every area of the garden, no matter what soil conditions they have to work with.
Iris Flowers for Many Garden Situations
In dry, well-draining soil (or container pots) the so-called Stinking Iris (I. foetidissima) does well and gives gardeners evergreen foliage with 3 foot tall, summer flowers. It also tolerates part shade better than most other iris species.
Bearded Irises (I. pumila is a dwarf form of bearded iris and I. germanica is the most common form) do well in sunny, well-drained soil that is slightly acidic. Sturdy flower stems, and hundreds of color choices, make bearded irises a popular cut flower iris choice for spring blooming gardens.
Wet soil, pond areas or boggy landscapes benefit from the moisture loving Flag Iris (I. pseudacorus). Most of the flag iris cultivars available have yellow blooms that appear faithfully throughout the summer. Blue flag iris (I. versicolor) also makes a great addition to a water feature or marginal pond planting.
Container plantings can be livened up with dwarf iris forms that tolerate periods of drought, such as the Dutch Iris group. Many of these beautifully colored irises grow only 6 inches tall, up to 18 inches tall. With the straplike foliage fans the iris bulbs will also add vertical accent to a container planting. The Dutch iris hybrids are often grown as annuals and are the species commonly used by florists.
Iris Flowers Throughout the Year
For a winter interest in the garden, landscapers often use reticulata iris which will sometimes bloom right through the snow in late winter or early spring. The bright purple flowers bring a lot of color to the late winter garden even though their size in small at only 6 inches tall.
Late spring to early summer blooming irises include the Siberian Iris (I. siberica), a beardless form, and the Juno group Irises (I. bucharica), which have fragrant iris flowers.
Mid to late summer irises include many of the flag iris plants, the Japanese water iris (I. ensata) and 'stinking iris' (I. foetidissima).
When to Plant Iris Bulbs
Iris flowers differ so widely in how hardy they are, gardeners will need to be sure they look carefully at the particular species they have. Some iris flowers will die in harsh winters and will need to be dug up and overwintered in cold, northern zones. Most iris bulbs can be planted in the fall, however, and will bloom the following spring.
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