Miniature Dwarf Bearded Irises

Miniature dwarf bearded irises grow to 8 inches or less in height. The flowers reach only 2 to 8 inches in height. The pumila types of irises don't have proper stems, but rather flowers growing on extended perianth tubes. In iris flowers, the perianth is a collective word for the standards and falls. These are the tiniest of the bearded irises and also the earliest to bloom. The miniature dwarf bearded irises are beautiful and reliable choices for rock gardens or when planted in drifts to give a colorful carpet like effect in early spring. Dainty and small, these irises are attractive in the very early spring when the tiresome winter is over and the iris clumps bear their bright little flowers.

History

The majority of miniature dwarf irises are descended from Iris pumila and I. lutescens (syn. I. chamaeiris). I. lutescens is native to dry rocky parts of southern Europe. Because of its great variety of colors-yellows, violets and occasionally white-I. lutescens has been known by many names. It even has been called, incorrectly, I. pumila, which causes further confusion. Indeed, the dwarf irises have commonly been called pumila irises for centuries.

In recent years, chromosome counts and cytogenetic studies have straightened out the relationships of these two major ancestors of miniature dwarf bearded irises. Some of the varieties originally considered to be pure I. pumila have turned out to be natural hybrids of I. pumila and I. lutescens. One of these is 'Atroviolacea', a famous cultivar known at least since the mid-1800s and often called the cemetery iris. This iris was carried across North America by early settlers and often used to cover graves. 'Azurea' and 'Coerulea', though not nearly as well known, have been cultivated at least since 1880.

I. pumila has served as a founding parent of three different iris classes since its arrival in the United States: the miniature dwarf bearded irises and also the standard dwarf bearded and intermediate bearded irises. The plant was originally brought to England by soldiers returning from the Crimean War. From these early imports came three major cultivars, a violet blue flowers 'Sulina', yellow flowers 'Carpathia' and red flowers 'Nana'.

Characteristic

Miniature dwarf bearded irises bloom along with daffodils. They are 8 inches or under in height, although varieties may be up to 10 inches tall. The flower stems usually are unbranched and the flowers are 2 to 3 inches in diameter. These are the earliest to bloom of all the bearded irises. The flowers should flare, stand up above the foliage and be in good proportion to the plant as a whole.

The most important species in the genetic background of modern miniature dwarf bearded irises is Iris pumila. Miniature dwarf bearded irises of pure I. pumila background seem to be nearly a class by themselves. Most these varieties include one-half to three-quarters I. pumila parentage. The remainder of the genetic background of these irises is often complex and comes from tetraploid tall or border bearded irises, the 40-chromosome species complex known as I. lutescens, and, increasingly, I. aphylla.

When growing these irises, you should remember that they are extremely variable in color from year to year and from garden to garden. A given variety might have a sharp and clear I. pumila spot pattern in one year or in one garden and have an indistinct fuzzy pattern in the next. Dark irregular streaking or blotching may appear in cold, wet weather on varieties that are normally clear. This is particularly noticeable on light-colored flowers.

Culture

If there is anyone single factor that will cause miniature dwarf irises to fail, it is poor drainage. These small irises must have well-draining soil. The slightest hint of sogginess can be enough to encourage rot. This is not surprising since some of their ancestors were originally collected on the rocky cliffs of eastern Europe and western Russia. Cold winters are another environmen- tal need for dwarf irises; in fact, the colder the winter, the greater the numbers of flowers for most of these plants.

The miniature dwarf bearded irises with a high proportion of pumila in their genes do not transplant well. They seem to take a long time for new roots to develop. Their dislike for being moved is sometimes reflected by a whole clump collapsing and dying. Other miniature dwarf bearded irises that don't have pumila genes will transplant better.

These irises will grow in more shade than the bearded irises that bloom later in the season. 'Perhaps that is because they bloom before tree leaves emerge. Because of their shallow roots, miniature dwarf bearded irises tend to heave during freeze-thaw cycles. This is no problem where snow covers them but can be a nuisance when there are open winters with little or no snow. Once the ground is frozen, cover these small irises with a light mulch such as loose straw or hay. Beware of letting too much soil accumulate on top of the rhizomes, especially during spring and summer when the irises are growing strongly.

Keep beds of miniature dwarf bearded irises weeded. Not only will weeds rob the irises of nutrients in the soil they may also shade the irises. Weed often and after rains have softened the soil to make the task far easier. When fertilizing, use a formulation or material that is high in phosphorus, the second number on fertilizer containers. Scratch the fertilizer into the soil around the plants.