Six on Saturday: Iris

Iris pseudata

A love for Iris began when I was still a kid in elementary school. A retired friend of my parents bred new varieties of German bearded Iris. One year he offered some of his discarded plants to my dad. Mom and Dad both loved gardening and flowers and readily accepted. The day that Dad went to visit and pick up the Iris, he came home with several grocery bags filled with muddy Iris rhizomes.

We all felt a little overwhelmed. What to do with so many new Iris? We had a large, sunny back yard. There were no fences to show where our yard stopped and the neighbors’ yards began, and very few trees. So Dad began digging long narrow beds for the Iris along the edges of the back yard, and he and Mom planted them all according the instructions he’d been given.

That next spring, as the Iris began to bloom, we were amazed by the vibrant colors and pure fragrance of these special iris. We’d never seen any others like these. Smelling the Iris was a bit like eating gourmet jelly beans, because each one had a very vivid, strong fragrance. There must have been more than 100 Iris plants in bloom that spring.

My parents dug and moved some of their Iris every time they moved after that and so Iris have been part of their garden and our lives ever since. I’ve always planted Iris around my homes, and have been fascinated by how many different types of Iris there are. I’ve expanded beyond the hybrid German bearded Iris they grew, to experiment with other species, too.

Iris bloom once a year, for a few weeks, and then either go dormant, or grow leaves only, for the remainder of the year. There are some varieties of ‘re-blooming’ hybrid German bearded Iris that may have a second season of bloom in the fall, if all of the conditions have been just right over the summer. I’ve had Iris re-bloom in November and December, which is always a beautiful and poignant surprise.

But each species or type of Iris blooms in its own particular time-slot during the unfolding of spring. Knowing this rhythm allows a gardener to plant for a sequence of bloom beginning in February or early March, depending on how severe winter may be, through June.

The last of our yellow flag Iris to bloom this year

Iris that grow from bulbs, like Iris reticulata and Iris histriodes open the season, soon followed by Iris bucharica and the hybrid ‘Dutch’ Iris. All of these are planted in the fall for bloom the following year. They should perennialize, but our hot, wet summers often cause their bulbs to rot. They prefer drier soil and more temperate summer temperatures. Most are originally from the mountainous regions of Europe and Asia.

Our German hybrid Iris, which grow from rhizomes, usually begin blooming by mid-April. Around the same time, we enjoy native Iris cristata, which grows in ever expanding clumps and makes a beautiful ground cover in part shade, and the elegant Japanese roof Iris tectorum. Roof Iris have traditionally grown on thatched roofs in parts of Asia, but they also grow well in a raised bed.

There are additional species of native Iris, Iris virginica and Iris versicolor, which begin to bloom in May. They are tall and resemble Siberian Iris, which also bloom in May. These don’t have strong fragrance, but have exquisite form and pure color. There is a hybrid of I. virginica and I. versicolor known as Iris x robusta, which is very hardy and beautiful. It often has purple at the base of each leaf.

Our tall native Iris are often called ‘Blue Flag Iris,’ and prefer growing in moist soil, along ponds and streams. The European ‘Yellow Flag’ Iris pseudacorus and the Asian Iris ensata are also known as wetlands Iris. Yellow Flag Iris were brought to North America early on with immigrants, but have now been declared an invasive species.

Many of these tall Iris with grass-like leaves spread on their rhizomes to form ever expanding clumps, and also spread easily by seed. Each flower produces a fat fruit that bursts with seeds later in the season. Yellow flag Iris is so beautiful that it is hard to give it up as an invasive plant. I grow it, but dead-head the flowers before they set seed and keep the plant contained to prevent spread into the wild.

The newest Iris hybrid is the Iris pseudata, which is a sterile hybrid of I. pseudacorus and the Japanese Iris ensata. The pure yellow colors of the yellow flag Iris are combined with the grace and form of the Japanese Iris. These are absolutely stunning. I ordered a few plants to try in 2019. I potted them at first, and then planted them in several different situation to observe their habit.

Iris pseudata

These are tall Iris, to around 5′, taller when they have consistently moist soil and plenty of room. They are vigorous and produce many flowers over several weeks. I like them so much that I just ordered five more plants this week from Ensata Gardens, whose owners are also busy breeding new selections of Iris pseudata.

They began blooming as the Iris x robusta and I. versicolor were finishing, and slightly before the Iris ensata. I expect to have iris blooming for at least another week to ten days, and the Japanese Iris will finish the season. Another North American Iris, the Louisiana Iris, also blooms in late May or June. I haven’t acquired those but they often have gorgeous red flowers.

All rhizomatous Iris are heavy feeders and want space to expand. Most benefit from thinning after a few years. Fertilizers should be balanced to support blooming but not be high in nitrogen, which may make them produce leaves at the expense of flowers. Most perform well in full sun, but many can also tolerate partial shade. Iris cristata needs part shade and moist soil and can be grown under deciduous trees.

Iris ensata

The main problem I have in growing Iris is with other plants crowding and shading them after they bloom. Because their season is so short, I often plant in combination with summer blooming plants. That can create problems, especially for the German bearded Iris who want light and air to expand all summer. I’ve vowed to do a better job with them this summer in hopes for more blooms next spring.

Iris are named for the Greek goddess of the rainbow for their clear, pure color. They herald the beginning of spring and summer each year, and have been grown for thousands of years in cultures around the world for their exquisite beauty. If you only try one new plant this year, let it be a new Iris. It will become a treasured feature in your garden.

Iris pseudata with Verbena bonariensis at the Williamsburg Botanical Garden

With appreciation to The Propagator, who hosts Six on Saturday each week.

You might enjoy my new series of posts, Plants I Love That Deer Ignore.