One would not dream of a well-planned late spring garden without at least a few varieties of iris standing among the aquilegia and peonies.
But what was the picture a few weeks earlier?
Perhaps a small group of daffodils looked out over the expanse of foliage from later blooming plants, or maybe a smattering of tulips was dotted irrelevantly here and there.
Perhaps, like so many gardens that lack suitable soil or location for a spring bulb display, there was no bloom!
In early May, my perennial garden was in this desolate condition a few years ago. Then I started planting some dwarf irises. That clump of daffodils looks at home in the impressive purple and gold ribbon that runs the entire border length.
Tulips took a new lease on life when intermediate irises were used to enhance their beauty—groups of pale pink tulips interplanted with a deep wine color, my favorite combo.
Over the years, the tiny species Iris pumila has been hybridized with tall bearded types giving us irises ranging in height from four to 24″ inches over a color range almost as extensive as that of the growing tall bearded irises.
Although small, the dwarfs carry blooms remarkably similar in form to their larger relatives. The narrow spear-like foliage of the dwarf irises can also play an essential part in foreground planting after bloom is over.
The following summer, single divisions planted six inches apart will form a solid border. Or they can be spaced unevenly to break up the monotonous flow of an annual edge such as alyssum or dwarf marigolds.
Dividing Necessary
Dwarf irises seem to propagate more profusely than the taller varieties (at least that has been my experience), and therefore the division of the clumps should be made every two or three years.
One variety, a red miniature of six inches, propagates so abundantly that a single rhizome will produce at least 20 divisions by the following spring.
Propagating and dividing can be done any time after blooming, provided enough time remains in late summer so the clumps can establish themselves before the ground freezes.
If there are many clumps of tall bearded irises and dwarfs and intermediates to divide, this job can be spread over a long period by starting on the dwarfs after they have bloomed and ending with late tall bearded.
Although a clump is best to be divided into single shoots, divisions consisting of three or four rhizomes will give a larger bloom display. Single divisions planted eight to 12″ inches apart in a triangle are also effective toward a mass of color.
Dwarf rhizomes resemble the more significant types except in size. Use only the rhizomes from outside, discarding the non-producing center part.
Pest Control
Although weekly spraying with Malathion starting in early April and continuing through June effectively prevents the iris borer, an infestation can still occur, especially during humid, rainy weather.
There is no better time than when clumps are being dug and divided to take steps to stop or prevent the iris borer and the rhizome rot it spreads.
Plants are laid in a pan with the rhizomes in Malathion solution and the foliage resting on the sides. As many as 75 divisions can be treated at once this way.
A cloth or newspaper is then thrown over it to discourage any thirsty pets that may unknowingly partake of this deadly poison. The rhizomes are left to soak for an hour.
If divisions appear weak, a teaspoon of a soluble fertilizer added to this solution will be an advantage in lessening the transplanting shock.
Rather than using the solution a second time, pour it on the remaining clumps in the ground, as soaking the soil around the plants is another effective way to control the iris borer and rots.
Planting Depth
Upon removal from the solution, plants should go immediately into the ground. Although a sunny position is advisable, shade from two o’clock on does not seem to hamper their growth.
Prepare the soil by adding sand for drainage, peat moss or leaf mold for hummus, and a little fertilizer for added nourishment.
Remove soil to a depth of four inches around a small mound in the center. Take an inch and a half off the top of this mound and place the rhizome on this with the roots spread out around it. Then fill the soil over the hearts and rhizome.
Care After Planting
Little care is needed after planting. A good soaking twice a week is necessary if a hot, dry spell follows the planting.
Hand pulling of weeds is necessary. No matter how careful one is with a hoe or even a small hand rake, the rhizomes can easily be pulled out by catching it or a root with the tool.
A light peat moss mulch is beneficial when applied to a new planting. It will conserve moisture and help prevent a hard soil crust from forming.
Unless planting has been done very early in the summer, some winter protection should be given the first year.
A light mulch of straw or evergreen twigs applied after the ground is frozen will prevent the small rhizomes from heaving.
Be sure to remove the covering early in the spring, for dwarf irises seem to know when to start growing, and any growth made under such coverage will be more susceptible to light freezing.
Dwarf irises, combined with many other early blooming perennials, can be very pleasing to the eye virtually days after the last freezing blast of winter.
Subulata, the low creeping form of phlox, offers innumerable opportunities for use when growing dwarf irises. Plants of the tiny reddish-purple ‘Tony’ placed through a solid cover of pink creeping phlox can genuinely enhance the beauty of a slope or rock garden.
One group of plants that must always neighbor each other in my garden are pale yellow daffodils bordered by lavender phlox and deep purple dwarf irises.
The bright yellow of perennial alyssum, when interplanted with a few divisions of a purple dwarf, can give your garden an eye-catching border already the last week of April.
Versatile Intermediates
Intermediate irises are just what their name implies – medium in height, taller than the dwarfs, but shorter than the tall bearded.
And they are intermediate in their blooming season, starting after the dwarfs have finished but a week or two before the tall bearded varieties come into bloom.
For these reasons, no iris planting should be made without at least a few intermediates. They are a little challenging to find, but many iris growers have lists of varieties from which to choose.
Many of these irises will reward the gardener with another bloom display in the fall. Irises coming into bloom with the mums and dwarf hardy asters can become subjects of widespread conversation.
If clumps are given good care through the summer with an emphasis on watering and frequent division, there is no reason why the fall show cannot be as great as the one in spring.
13204 by NA