I cannot recall any other genus of plants, except primula, that begins to match the iris in size and shape of flowers, range of colors, and adaptability to various garden uses.
The bearded iris group is the most widely-grown, including tall, intermediate, and dwarf kinds.
The less common oncocyclus and regalia groups are not well known because their culture is difficult except in regions with mild winters and hot, dry summers.
But it is with the beardless division, this article is concerned, special emphasis being on the popular bulbous, Japanese, crested, and Siberian groups.
Bulbous Iris
The most important of the bulbous irises include the:
- Reticulata
- The xiphium sections
Iris Reticulata
Iris reticulata is so called because of the fibrous netted covering of the bulbs.
It is one of the first to bloom, displaying its flowers, blue-purple marked with bright orange-yellow, from the first to the middle of March in climates similar to that of Long Island, New York.
The flowers are fragrant with the odor of sweet violets and attain a height of about 6″ inches.
Ultimately the four-angled leaves grow to about 12″ to 15″ inches.
There are several varieties of Iris reticulata, including:
- Cantab – flowers are Cambridge blue
- Iris Krelagei – flowers are red-purple
Iris Danfordiae is a tiny species with brilliant yellow flowers marked with dark greenish spots at the base of the falls.
They attain a height of about 3″ inches. This is a jewel for the rock garden.
A group growing in my wife’s rock garden (Hyde Park, New York) was in bloom on March 22 this year.
Another species, Iris Vartani, is even more precocious—I have known it to bloom during the first 2 weeks of January. Then after a cold spell caused it to close up shop until February 20, it flowered continuously until the middle of March.
This does not exhaust the tally of the early-flowering bulbous iris.
There are several more, including:
- Iris histrio
- Iris histrioides
- Iris persica
Bulb dealers in America seldom offer these species.
Cultivation
All of these irises require well-drained soil and a sunny location.
Their comparatively small size makes them eminently suitable for the rock garden.
Iris reticulata is especially valuable for, when it is properly situated, the bulbs will multiply so that the clump increases in size and beauty from year to year.
Dutch Bulbous Iris
These are more spectacular than those previously mentioned in that they grow to a height of 18” to 26” inches.
The Dutch irises are a result of hybridizing the Tangier iris (Iris tingitana), the English iris (Iris xiphioides), and the Spanish iris (Iris xiphium).
One of the Dutch irises, Wedgewood, is commonly forced by florists and sold as cut flowers in late winter and early spring.
Other good varieties of iris include:
- Belle Jaune – yellow and orange
- Blue Champion – large flowers of Wedgwood blue
- White Perfection and Princess Irene – white standards and orange fall.
Cultivation
These irises start growth in the fall, so, in northern regions, to minimize injury to the foliage, bulbs should be planted 6” inches deep as late as is consistent with getting them into the ground before it freezes.
These can be forced into bloom for use indoors or planted outdoors in beds or borders.
They are best in gardens south of the Mason-Dixon Line. The English varieties are the latest to bloom and grow best in moist soil.
Japanese Iris
For the most part, the Japanese iris is varieties of Iris Kaempferi and, when well grown, is among the most spectacular of all iris.
Under favorable conditions, the flowers of some varieties may attain a diameter of 10″ inches.
The blooms, in general, are flat, and some of them are “double.” The standards assume the size and shape of the falls.
The flowers exhibit an amazing range of bulb colors. They may be stripped, stippled, or veined in violet, blue, white, mahogany, red, or pink.
Practically all of them have more or less conspicuous orange or yellow markings near the center.
Because of the plants’ habit of holding the flowers horizontally, they are best viewed from a slight elevation. This could be made possible by planting them at the foot of a terrace wall.
The terminology of Japanese iris is almost hopelessly mixed.
Early importations from Japan had Japanese names. These, unfamiliar as they were to American gardeners, became garbled.
Some nurserymen had the names translated into English, while others raised the iris from seed and applied their own names to the plants.
Thus, the same plants masquerade under several different names, which makes confusion even more confounded.
So instead of giving you names that might be worthless, I would suggest that you visit an iris nursery in July to see varieties in bloom and get catalogs illustrated in color from specialists such as Walter Marx Gardens, Boring, Oregon, whose catalog is worth more than double the modest cost of 250.
Cultivation
Although they can be grown in the ordinary moist soil of the perennial garden, they appreciate ample supplies of water from the time they start growth in the spring until blooming season is finished.
They are particularly well adapted for stream-side or pond planting and may be planted in or near shallow water in a lily pond.
The soil should be rich, moisture retentive, and have a pH between 5.5 and 6.5.
It is desirable to enrich the soil with rotted manure or peat moss to these ends.
The latter is especially valuable if the soil is sandy or alkaline. Planting should be done early in September or the spring.
Siberian Iris
“Siberian” is a misnomer as far as these iris are concerned, for they are native to central- Europe and Russia.
Their foliage is almost grass-like. Their flowers, typically blue-purple with perky standards and roundish falls, are produced on slender stems and held well above the foliage.
They range in height from the 12″ inches of Acuta, with blue and white flowers, to the 50″ inches of Caesar’s Brother, which has pansy-purple flowers.
Other good varieties include:
- Caesar – violet-blue. 4′ feet tall
- Eric the Red – red and white
- Gatineau – large medium-blue flowers, 4′ feet tall
- Snow Crest – white, slightly ruffled
- Tropic Night – deep violet-blue
Cultivation
While Siberian iris can be grown in almost any soil and take kindly to the conditions of the average flower border, they are likely to make a better showing if the supply of water is practically unlimited from the time growth starts in the spring until about midsummer.
They are admirable for stream-side planting.
Crested Or Evansia Iris
These iris are distinguished by possessing a crest or cockscomb effect along the haft of the falls.
The best-known of these crested irises is Iris cristata which is native to this country and grows wild from Maryland to Georgia and Missouri.
Two Japanese forms are fairly well known in America, namely:
- Iris tectorum – the roof iris
- Iris gracillipes
Of these, Iris cristata is a delightful dwarf iris that grows about 4” inches tall with pale-blue flowers and a white and yellow crest.
There is a white form that is exquisite, but I found it to be less robust than the typical cristata.
However, I have known it to grow happily when planted on the north side of a large boulder.
If this iris fails to bloom, it may be because it has too much shade. If, on the other hand, the foliage becomes yellowish, it may be getting too much sun.
The roof iris, Iris tectorum, is a good conversation piece because you can tell your visitors the story of how it got its common name.
Once upon a time, there was a long famine in Japan, and the Mikado issued an edict that required that nothing be planted in the ground unless it was good for food.
Japanese ladies, who used the ground-up rhizome of Iris tectorum as face powder, could not get along without it, so they planted it on the thatched roofs of their homes, where it has been grown ever since.
Iris gracillipes is a charming little plant that usually grows best in a shady part of the rock garden.
Small lavender flowers are displayed on slender stems which rise about 6” inches above the ground.
44659 by M. Free