When you see a tall, stately stand of iris, it’s easy to fall under the spell of their majestic grace.
A hardy herbaceous perennial, iris is both the common and botanical name for this large genus in the Iridaceae plant family.
Classified as either bulbous or rhizomatous, both types clump and multiply with ease. Blooming in late spring and early summer, they present a striking display – showy flowers set atop tall, slender stalks and framed with spear-like fans of leaves.
Native to the temperate regions of Europe, Asia, and North America, their habitat is diverse. They can be found growing in arid and semi-desert regions, on rocky slopes, grassy banks, in meadows, bogs, and along riverbanks.
They’re also a superb choice for steep or difficult slopes, to help prevent erosion.
Available in shades of white, yellow, pink, orange, red, maroon, mauve, chocolate, blue, and purple, they put on a spectacular show that can be extended by planting different species and varieties.
Irises are also sweetly fragrant, with a scent like violets – and the darker the flower’s color, the more intense the fragrance.
The Royal Standard
Named after the Greek goddess of the rainbow, their appearance is regal and elegant. Small wonder that throughout the ages, regents and monarchs have used them to symbolize their royal houses in the form of the fleur de lis.
The fleur de lis is often found on flags, standards, and coats of arms around the world – and while some will argue that the fleur in question is a lily, most heraldologists agree it represents a stylized version of the species I. pseudacorus, or I. florentina.
There are some 300 species within the Iris genus along with several sub-species, all of which display elaborate flower heads comprised of three large outer petals called “falls” that flare out or drop downwards, and three inner, upright petals known as “standards.”
Several species have falls with either “beards” or “crests,” which are so-named because of a small mat of soft, short hairs located at the base of the falls. In crested types, the hairs are replaced with a crest, or pleated ridge.
- Each stem produces clusters of 9-12 flower buds that bloom on short side stems
- Darker flowers produce a more intense fragrance
- Iris are an important flower for attracting bees, hummingbirds, and butterflies
- All varieties are based on three group sizes – dwarf, intermediate, and tall
Where to Buy
The royal purple ‘Attention Please’ is an excellent example of a bearded cultivar of I. germanica, as it clearly shows its beard in a bold, contrasting orange. A true showstopper, ‘Attention Please’ can be purchased from reliable online sites like Nature Hills Nursery.
Beardless varieties often have a “signal” on the falls, which consists of a flash of contrasting color in place of a beard.
The splendid deep blue ‘Caesar’s Brother’ is a beardless cultivar of I. siberica, and is a good example of the signals found on these varieties – it, too, is available for purchase at Nature Hills Nursery.
Most irises flower in early summer. But some, mostly bearded hybrids, are remontant – meaning they’ll also flower again later in the summer.
The snowy white ‘Mount Everest’ with its sunny yellow signal is a beautiful bulbous cultivar of I. hollandica, or Dutch iris, and can be purchased through Amazon.com.
From Perfume to Gin
Orris root is the dried, powdered root of I. germanica, I. pallida, or I. florentia.
It has long been an ingredient in traditional herbal remedies, but today is used primarily as a base note in perfumes. With a delicate fragrance similar to that of violets, it’s also used as a fixative in perfumes and in potpourri blends.
Orris root has uses in the kitchen as well, and is one of the 30-plus spices that may be included in ras el hanout, a spice blend used in Morocco and other North African countries that is unique to family and region, much like the Indian garam masala.
Distilled, orris retains its floral notes, and is used to add depth and color to many brands of gin, adding a sweet, earthy flavor.
Care and Cultivation
Irises do their best in strong light, with at least six hours of sunshine a day.
They prefer a neutral soil, with plenty of organic material worked in, and good drainage. And many prefer to be located in a bed of their own.
Before planting, soil should be loosened with a fork to a depth of 12 to 16 inches, with 2 to 4 inches of compost or well-rotted manure mixed into the top layer.
Rhizomes can be planted any time after blooming, from mid-summer to early autumn, and bulbs can be planted in spring or fall.
To plant, dig a hole a few inches longer than the rhizomes, and about four inches deep. Pile some loose soil into a ridge down the middle, then place the rhizome on the ridge, laying the roots down on both sides.
Pull the soil into the hole, covering the roots but leaving the top of the rhizome exposed. Firm the soil in place and water deeply.
Plant rhizomes singly or in groups of 3 or 5, with the fans outermost and spaced 1 to 2 feet apart, depending on the size of plantings.
When planting, apply a low nitrogen fertilizer and reapply again in early spring. A good choice is a perennial plant food such as Medina’a Hastagro, available on Amazon.
When working with soil and mulch, it’s very important to leave the rhizome tops exposed to the drying sun and air. If covered with soil, or overly crowded, the excess moisture can lead to rhizome rot.
Once they’ve finished blooming, cut back the flower stalks, but leave the fans in place. Trim any brown tips if needed, but preserve the leaves, as they are required to produce energy for next year’s growth.
To rejuvenate plants and keep the bloom count high, clumps should be divided every 3 to 5 years. Dig up rhizomes and divide with a sharp garden knife, discarding any pieces that are soft or damaged.
To keep weeds down and roots moist, mulch beds lightly to a depth of two inches – but remember to keep the crowns clear.
For bulbous varieties, plant as you would other bulbs.
Loosen the soil to a depth of 12 inches, working in some organic material and bone meal. Plant in groups to a depth of 4 inches, leaving 2 to 3 inches between the bulbs.
In areas with cold winters, mulch the bulbs with a thick layer of dry straw, or plant in the spring and treat as an annual.
Bulbous irises are hardy in zones 6-9, although many species will survive zone 4 and 5 winters.
Rhizomatous varieties are reliably hardy in zones 3-10 in areas with dry summers, and zones 3-8 in regions with warm, moist summers.
Pests and Problems
Deer resistant and drought tolerant, irises usually enjoy good health. However, the rhizomes can be targeted by borers and should be checked on a regular basis for small holes. Any found to be infested should be removed and discarded.
Keep your iris beds clean to thwart the iris weevil. In autumn, moths lay weevil eggs on decaying leaf matter and debris. Come spring, small white caterpillars start munching on the stalks and work down to the rhizomes as they mature.
Fungal crown rot, or Sclerotium rolfsii, is a spreading, soft gray mat that covers rhizomes and the base of leaf fans, and most often appear in warm, moist conditions.
Crown rot can be alleviated by maintaining sanitary garden beds and with the prompt removal of any infected material. If this is a problem in your area, disinfect rhizomes before planting by dipping in a 10 percent solution of bleach and water.
Bacterial soft rot can be a problem for bearded iris, and is most likely to occur during warm, wet springs. Symptoms include soft, smelly rhizomes, decay at the base of leaves, and a wilting of the fan.
If the soft rot pathogen Erwinia carotovora does present itself, scoop out infected areas with a spoon and let the sun dry out remaining tissue. After sun-drying for several hours, sprinkle the wound with a chlorine cleanser like Comet, or garden sulfur to make the tissue inhospitable to rot bacteria. Garden sulfur is available via Amazon.
Goddess of the Garden
Dazzling in the early summer light, when you see their tall silhouettes and dramatic colors, or catch their sweet fragrance, you’ll wish you’d planted more!
Remember to give them plenty of sunshine, provide excellent drainage, and keep the tops of their rhizomes exposed to the sun and air. Use a low-nitrogen fertilizer at planting, and apply once more in early spring to help the flowers to set.
Given the conditions they enjoy, they’ll produce masses of flowers for your enjoyment year after year!
Do you readers have any favorite iris varieties in your gardens, or questions about growing them? Drop us a note in the comments below, and check out our article on how to care for another species, the unique bicolor iris!
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Photos by Lorna Kring, © Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Product photos via Nature Hills Nursery, Greenway Biotech, Medina, and bulbsdirect. Uncredited photos: Shutterstock. With additional writing and editing by Allison Sidhu.
The staff at Gardener’s Path are not medical professionals and this article should not be construed as medical advice intended to assess, diagnose, prescribe, or promise cure. Gardener’s Path and Ask the Experts, LLC assume no liability for the use or misuse of the material presented above. Always consult with a medical professional before changing your diet or using plant-based remedies or supplements for health and wellness.
About Lorna Kring
A writer, artist, and entrepreneur, Lorna is also a long-time gardener who got hooked on organic and natural gardening methods at an early age. These days, her vegetable garden is smaller to make room for decorative landscapes filled with color, fragrance, art, and hidden treasures. Cultivating and designing the ideal garden spot is one of her favorite activities – especially for gathering with family and friends for good times and good food (straight from the garden, of course)!