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The Ethereal Iris
Gardening Newsletter
Vol. 7, Issue 2 - April 2012
Irises of various colors and heights look lovely in any garden.
According to Roman mythology, Juno, queen of the gods, sent her messenger
Iris to earth to bring good news to humanity. Upon her arrival, she went to work
spreading glad tidings. It is said that from each of the rainbow goddess’s earthly
footprints sprang the extraordinarily beautiful flowers we call irises.
Botanical Traits
Irises belong to the family Iridaceae. They have a single cotyledon (seed leaf),
long, strappy leaves with parallel veins and flower parts in sets of three. Some
grow from rhizomes (fleshy underground stems), others from bulbs. Their
flowers each have six tepals - the three that droop are called falls and the three
upright ones are called standards. The standards surround three more petal-like
structures that form the plant’s reproductive system.
Planting
Some irises prefer to be planted or uprooted in late summer, others in spring.
Either way, they need to be lifted every three to four years to renew performance
and productivity. After lifting, cut away rotten or damaged parts, clean and dry
the healthy parts and cut back the leaf blades to 15cm to 22cm. Excavate the
site to a depth of 15cm and remove all old plant residues. Provided there is no
evidence of borers, the old soil can be mixed with new soil, compost, bone meal
and a small amount of commercial fertilizer (5-10-10). Leave the mixture to settle
for a few days before replanting. Position the irises in groups with fans pointing
in the same direction and rootlets spread neatly around the rhizomes. Pat down
the ground around them.
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The Ethereal Iris
Gardening Newsletter
Vol. 7, Issue 2 - April 2012
Management
Most irises tolerate poor soil and a degree of drought, but if you want the best
blooms possible, add organic material regularly and water generously on a
weekly basis during dry spells. When adding soil or compost, the rhizomes should
remain partially exposed or only lightly covered. Bulbs can be set more deeply.
If your garden consists of heavy clay, a raised bed may help improve drainage.
Most irises do best in slightly acidic soil (pH of 6.0 to 7.2). If you add lime to
elevate pH, do so well in advance of planting. Apply organic and/or synthetic
fertilizer in early spring and again when blossoms are spent. If using synthetic,
emphasize phosphorus, the middle number of the NPK (nitrogen, phosphorus,
potassium) trio. Prompt deadheading directs plant energy into roots and blades,
and regular removal of damaged, dead or diseased parts enhances plant health
and vitality.
Bearded Ladies
Bearded irises or pogons, sometimes
referred to as German irises (Iris
germanica), are all rhizomatous,
including the more difficult arils. Their
beards, located on the falls, not only
look beautiful but are also great pollen
catchers and provide excellent traction
for insects. A seed stalk, surrounded
by pointed, strappy leaves in fan-like
sets, supports one or more flowers at
a time. Bearded irises are grouped
according to height: miniature dwarf,
standard dwarf, intermediate, miniature
tall and tall. The tall grow over 70cm
(28”), while the mini dwarfs grow only
up to 20cm (8”). The shorter they are,
the earlier they bloom.
A spectacular example of a bearded iris
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The Ethereal Iris
Gardening Newsletter
Vol. 7, Issue 2 - April 2012
Beardless Ladies or Apogons
Hardy Siberian irises (I. sibirica) bloom later than bearded irises and are less
exuberantly colored, although they are impressive when properly used. They
grow in clumps, with each plant reaching up to 90cm in height. Their smaller
blooms, which come in wine-red, purple, lavender, blue and pink and white, have
their own special beauty. I. laevigata requires more moisture and looks lovely
beside a pond or in a semi-shaded moist location. Japanese irises (I. japonica)
are flatter in form and have been highly hybridized. These beauties are quite
hardy and do well as long as they are kept moist and well fed. Lousiana hybrids
are said to be quite hardy, although they usually don’t thrive in cooler regions.
They require long, hot, humid summers. Beardless iris needs are similar to those
of their bearded cousins. They can be planted in early fall and covered with
mulch for winter.
Beardless irises have smaller blooms than the bearded and grow in bunches.
Other Beardless Irises
Crested irises (I. cristata), also known as Evansia or orchid irises, are North
American natives suitable for use as ground cover in moist, shaded areas. Their
most prominent characteristic is the crest on the haft (base) of each fall. Stinking
iris (I. foetidissima) has an unpleasant odor but redeeming bright-red seeds.
Savannah iris (I. tridentata) has a lean trident-shaped structure.
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The Ethereal Iris
Gardening Newsletter
Vol. 7, Issue 2 - April 2012
Bulbed Irises
These have smaller blossoms and shorter leaves. I. reticulata are fragrant,
early-blooming dwarfs that are available in many colors. They are also great
multipliers. Though Dutch, Spanish and English irises of the xiphium group need
little care other than winter mulching, they can be short-lived. Bulbous irises can
be planted in early fall or early spring at 10cm to 15cm deep and 10cm apart.
The bulbs can be divided, and the offsets replanted or discarded.
A Few Design Suggestions
1. Iris leaves provide structural interest in the garden. Avoid cutting them back
until fall.
2. Prolong blooming periods using irises of different heights. (Shorter irises
bloom earlier, taller irises later.)
3. Apogon irises bloom later than pogons, further extending the blooming period of your iris collection.
Text by Edythe Falconer
Photos by Richard Hinchcliff
Edythe has been a volunteer with Master Gardeners of Ottawa-Carleton since
1999, and with Friends of the Farm since 2004. She regularly writes for local
newspapers and gardening newsletters, and does presentations for various
gardening groups.
Richard Hinchcliff has been a volunteer with the Friends of the Central Experimental Farm, in Ottawa, Ontario, for 10 years. He is co-author of For the Love
of Trees: A Guide to Ottawa’s Arboretum, now in its third printing. He edits the
Friends’ newsletter and is their website manager.
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