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Our flower gardens are full of history, and flowers have served as inspiration to poets and painters. In Greek mythology, Iris was a messenger of the gods who used the rainbow as a pathway to Earth. Everywhere she stepped, iris would bloom in almost every color of the rainbow. The iris symbol has appeared in the art of ancient Egypt and Islam and is said to have inspired the fleur-de-lis, which is the floral symbol of France.
The bearded iris is one of the most glamorous flowers of late spring, and it is also one of the easiest perennials to grow in Colorado. Their distinctive structure has three large downward facing petals, known as "falls," three upright inner petals known as "standards," and hairy filaments on the center of each fall near the throat known as "beards." The scent is intoxicating, and until recently, many perfumes were distilled from the iris. After blooming, the sword-shaped foliage lends lush color and interesting texture to any landscape.
Iris need to be divided every three to four years in order to insure a healthy plant and continued robust bloom. If not thinned, the iris will become crowded, some varieties may crowd others out, and the plant may eventually stop blooming.
Peak bloom time in Colorado is usually late May and early June. The best time to plant iris, or remove old divisions and replant the new growth, is in July or August. It is important that the roots of the newly planted iris be well established before the growing season ends.
Keep your iris beds clean and free of weeds and debris. Bloom stems should be cut off close to the ground after blooming, however, the healthy green leaves should be left undisturbed. Remove diseased or brown leaves. Clumps may be thinned by removing the old woody divisions at the centers of the clumps and leaving the new growth in the ground. Or, you may dig up the entire clump with a garden fork, remove the new rhizomes with a sharp knife and replant them.
Iris will thrive in almost any well-drained soil. They do not like wet feet, so planting on a slope or in raised beds helps ensure good drainage. The tops of the iris rhizomes should be just below the surface of the soil, allowing the rhizome to be warmed by the sun. A common problem is to plant the rhizome too deeply. Set the rhizome on a ridge of soil and spread the roots down the sides of the ridge you created. Then cover the rhizome and the roots with soil, making sure the foot is kept parallel to the surface.
Iris should be planted 12 to 24 inches apart. Close planting of the rhizomes will give an immediate impact of color, however, they will need to be thinned more often. Plants spaced further apart will need less frequent thinning.
The new plantings require consistent moisture to help their root systems become established. Once established, irises don't require as much watering.
There is an extra hardy strain of iris that has been crossbred to re-bloom in mid summer. Innovative hybridizing methods in the professional horticulture field have provided gardeners with a choice of easy-to-grow and reliably re-blooming iris with attractive features like, a variety of soft and bright colors, and a choice of sizes.
Iris is an easy plant to grow. Give them plenty of sun, a little food, don't over water, and keep the weeds away and you will be rewarded with their beautiful blooms and intoxicating fragrance.
Additional information can be obtained from Fact Sheet #7.405 Herbaceous Perennials or Fact Sheet #7.231 Xeriscaping: Garden Flowers.
Q: The weeds in my garden are taking over. What can you recommend?
A: First of all, get to know your weeds. Respect them, but
don't knuckle under. Weeds like flowers are either annual or perennial,
or sometimes biennial. Annual weeds such as crabgrass, purslane and
pigweed grow, set seed and die within a year. They are easiest to
pull or kill when they are young, but if you don't get them at this stage,
be sure to deadhead them before they set seed. That way, you've eliminated
next year's crop. Perennial weeds such as bindweed, thistle, and
dandelion may reproduce both by seed and by underground roots or stems.
Unless you pull out the plant with its entire root system intact, even
a fragment of root left in the soil may sprout. Biennial weeds like
mullein and wild mallow produce foliage the first year, set seed the next.
Treat them like perennials the first year: when they bloom, chop off their
heads as well as their seeds. Weeds grow where there is room for
them, so one of the best ways to control them is to crowd them out.
Mulching bare soil is the easiest most effective way to foil weeds.
Mulch mimics nature's own cover, and is a guaranteed weed prevention by
depriving the weed seeds the sunlight that is necessary for germination.
Xeriscape Perennial Garden
Starting a xeriscape flower garden in your yard is not that difficult.
Xeriscape (pronounced zer-i-skape) is a type of landscaping that conserves
water through a variety of methods. One of these methods is plant selection.
You might already have many of the plants often used in xeriscape. These
include columbine, bleeding heart, bearded iris and daylily just to name
a few. There are plants for shady spots, sunny spots and those that
work well in rock gardens.
Blackspot on Roses
Blackspot on rose is a fungus that often appears on roses during this
time of year. Symptoms include black spots or patches on rose leaves beginning
in mid-summer. The leaves will often turn yellow and eventually fall
off. In Colorado, the disease is more common on some old-fashioned
varieties. Try to plant rose varieties that have disease resistance.
Control includes removing infected leaves and destroying them. A
fungicide can be used to control the fungus. Always follow instructions
carefully when using chemical controls, making sure to properly mix and
apply them.
The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.
Fact Sheets are available at the Larimer County Extension Office, 1525 Blue Spruce Drive, Fort Collins, Colorado, telephone (970) 498-6000, or contact us by e-mail at larimer@coop.ext.colostate.edu
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