Monday, February 2, 2015

The Earliest Irises: Welcoming Spring

by Tom Waters

reticulata iris 'Katharine Hodgkin'

While I enjoy the rest and simplicity that winter brings to the garden landscape, by January or February I find myself looking ahead eagerly to spring. Most gardeners think of irises as late spring flowers, bridging the time between spring bulbs and summer perennials. But there are many wonderful irises that bloom much earlier, and help the impatient iris lover through the long wait for bloom.

I garden in what is now zone 6 in northern New Mexico. (The older USDA map had us in zone 5). Here the last frost is usually in May. Tall bearded irises bloom in late May and early June. But my iris season begins in February, or sometimes even earlier!

Reticulata Irises

Iris danfordiae
The earliest of all irises in my climate are the reticulata irises (sometimes sold as “rock garden irises”). They often bloom right through the snow! These grow from bulbs, resembling crocus corms. They bloom along with the crocuses too, which is usually March here. However, I have a warm flower bed along the southeast side of the house, where spring bulbs bloom a month or more before those in the main garden. Here the reticulata irises are in full bloom in February; in some years they begin late in January.
reticulata irises blooming in the snow

These are small flowers, about the size of crocuses, though a bit taller. Most of the widely available ones are shades of blue, violet, or purple, often with a contrasting orange or yellow stripe on the falls. The earliest of all is the yellow Iris danfordiae. This little charmer has almost no standards, the shape of the bloom being formed by its wide falls and style crests. Its bright yellow color is accented by small leaf-green dots.

reticulata iris 'Cantab'
The blue, violet and purple forms in commerce are mostly forms and hybrids of Iris reticulata and Iris histrioides. Some of my favorites are the light blue 'Cantab' and the dark blue 'Harmony'. There are also white ones, and a lovely pastel blend of sky blue, cream, and gray tones, 'Katharine Hodgkin'.

These wonderful irises are available inexpensively almost anywhere you can buy crocuses, daffodils, and tulips. In some gardens, they multiply from year to year. Elsewhere, they may dwindle away. (Planting deeply may help.) But they are inexpensively replaced and well worth it for the cheer they lend to the late winter garden. It’s surprising that they are not as widely grown as crocuses or snowdrops. They surely deserve to be!

Dwarf Bearded Irises

Iris pumila
Iris pumila
Among the more familiar bearded irises, the earliest to bloom are the miniature dwarf bearded (MDB). Although these grow from rhizomes like their tall bearded cousins, they are less than 20 cm (8 inches) In height! An established clump presents a carpet of color before the taller ones are even sending up their stalks. These are available in a wide range of colors, patterns, and flower shapes to suit every taste.

Iris pumila 'Steppe'
In my garden, the bearded iris season begins with the species Iris pumila. This little gem is native to eastern Europe, from Austria to the Caucasus. Bloom usually begins here around the beginning of April, and carries on for a full month. The dainty, perky blooms come in violet, blue, yellow, cream, and white, often with a contrasting darker spot on the falls. They have hardly any stem at all, blooming right on the ground, with the tops of the blooms just a few inches above the soil. There are some named cultivars of the species, such as the well-known 'Little Drummer Boy', 'Suslik', and 'Hobbit', as well as more recent introductions such as 'Steppe', 'Royal Wonder', and 'Wild Whispers'. To find this delightful species, you will have to turn to specialist nurseries, either iris enthusiasts are rock-garden aficionados who seek out wild plants from around the world. Beware that there is an unfortunate practice in the nursery trade of labeling any small bearded iris as “Iris pumila”; if you see such a label at a local garden center or home improvement store, it is almost certainly not the real species.
Iris pumila 'Royal Wonder'

Iris pumila comes from regions where it is cold in winter. It does fine in my garden, where winter temperatures down to around 0 F are normal, but growers in warmer-winter climates report that it does not persist well for them.

There are two similar species, Iris attica and Iris suaveolens, that come from the southern Balkans, Greece, and western Turkey. It seems these might do better in warmer gardens, but they are not widely grown. Again, you will need to seek them from specialists.

Iris suaveolens
MDB iris 'Rosa Brooks'
Easier to find are the hybrid miniature dwarfs, derived from Iris pumila but with some tall bearded irises in their ancestry as well. These tend to be a bit larger than Iris pumila, and bloom later. Their time is late April into early May in my garden. Although not commonly found at garden centers, many commercial iris growers list some of them. These are available in all the colors seen in Iris pumila, as well as other colors from their tall bearded ancestry, such as pink, orange, plicata, and sometimes contrasting red or blue beards! They are quite adaptable to different climates, although most appreciate a winter chilling.

Some favorites of mine are'Alpine Lake' (white with a gentle blue spot), 'Icon' (bright orange with a darker spot) and 'Dollop of Cream' (ruffled creamy white).

MDB iris 'Icon'

By the time the miniature dwarfs have finished, iris season is well underway, with medians and arilbreds beginning to bloom and the tall bearded not far behind.
MDB iris 'Alpine Lake'

MDB iris 'Dollop of Cream'

I do love the head start on spring these earliest irises provide, but I would grow them even if they bloomed later. Their charm and daintiness speaks to me, and I enjoy the variety and fun they add to an iris collection.


  1. Great article, Tom. Love the little irises, wish I could grow them in my warm climate. I really like the varieties you present here. Thank you.