We’re now at the peak bloom period of the highly regarded garden plant, the iris. For the Monterey Bay area, the popular tall-bearded irises typically reach their peak blooms from the end of April to the beginning of May.

The bearded iris category includes varieties in several different heights. In my garden, tall-bearded irises and beardless Pacific Coast irises are both in bloom.

The other beardless irises — spurias, Siberians, Japanese and Louisianas — typically bloom in late spring and early summer.

In celebration of irises in bloom, the Monterey Bay Iris Society will present its annual show on April 26, 1 to 6 p.m., and April 27, 10 a.m. to 5 p.m. The event will be held at the London Nelson Community Center, 301 Center St., Santa Cruz. Admission is free.

This show provides an opportunity to display the results of the skillful cultivation of unnamed seedlings and established cultivars, and to encourage all gardeners to examine high-quality specimens and select options for their gardens. Later in the season, this column will invite interest in the society’s iris sale, scheduled in August.

This column’s image gallery includes examples of tall-bearded irises and one example of a Pacific Coast iris. The captions are edited from the American Iris Society’s Iris Encyclopedia and include bloom period, description of the bloom, hybridizer’s name and date of introduction.

Brief overview of irises

The iris plant family (Iridaceae) includes 66 genera, including freesias, gladioli and crocuses. The iris genus includes about 300 species. Taxonomists have organized these species into several sub-genera, each containing numerous species. The broad categories are bearded, aril and beardless irises.

Bearded irises are characterized by bushy, hairy growths (“beards”) on their lower petals. This group includes some 30,000 hybrids. They are available in different heights: miniature dwarf bearded, standard dwarf bearded, intermediate bearded, border bearded, miniature tall bearded and tall bearded.

Aril irises, native to the Near East, have sparse beards and other distinguishing characteristics. Crosses of arils and the more common bearded irises are called “arilbreds.”

Beardless irises include mostly Asian species: spurias, Siberians, Japanese and Louisianas. Other groups of beardless irises are the Pacific Coast natives, which are native to America’s West Coast, and the species irises.

Irises are noteworthy for their wide range of blossom colors. Most bearded irises are in the purple and blue range, with yellow, pink, orange and white breeds also available. Only true red blossom color has been the hybridizers’ elusive vision.

Iris blossoms are available in 11 named color patterns, with the top three petals (“standards”) being one color and the bottom three petals (“falls”) often another color (see “Advance your knowledge” below for more on this topic).

Irises are popular for home gardens based on their astonishing range of blossom colors and forms, their easy cultivation and their natural conformation to the Monterey Bay area’s climate. These plants grow well in a wide range of temperate Northern Hemisphere zones, and most species adapt well to dry environments, making them good choices for occasional drought conditions.

More about the Monterey Bay Iris Society

This year, the society marks its 50th anniversary and honors Joseph Ghio, its founding member and international iris hybridizer.

The society is a member of the American Iris Society, which has 24 regions in the United States and Canada, as well as a member of AIS Region 14, which includes Northern California, Nevada and Hawaii. The society is a nonprofit mutual benefit corporation whose sole purpose is promoting the culture and improvement of the genus iris.

Ghio began growing irises in 1953 as a teenager and became well-versed by 1960. He served as a high school teacher and a three-term member of the Santa Cruz City Council (including three years as mayor). Meanwhile, he earned worldwide recognition as a hybridizer of tall-bearded and Pacific Coast irises, introducing 924 innovative hybrids and earning numerous American Iris Society awards. His awards include the Dykes Medal in 1980, the highest honor given to a single iris each year, for his hybrid ‘Mystique.’ He has also received several Sidney B. Mitchell medals for his Pacific Coast iris hybrids.

The Monterey Bay Iris Society is also hosting its Iris Art Show during April, complementing its iris show at the London Nelson Community Center. The Iris Art Show features the work of local artists, and is displayed on the community center’s hallway walls.

This week in the garden

If you already have tall-bearded irises in your garden, Ghio provides this expert advice (quoted from the Monterey Bay Iris Society newsletter): “We had some rain that worked the fertilizer in the ground. It gives the irises the nutrients they need to perform well. But, if you fertilized the irises as the new growth began in early February, the rains likely leached away some of the benefits of that fertilizing, so it would be well to give them another light application now. Apply it as you have before and work it into the soil, but if the rains continue, that will do the job.”

Advance your knowledge

For an expert introduction to growing irises, visit the website of the American Iris Society (irises.org). Click on the Gardeners menu and scroll down to Cultural Information and Care & Classification. This website includes a link to the impressive Iris Encyclopedia (wiki.irises.org) and other resources for iris lovers.

The Monterey Bay Iris Society provides more information on irises. Visit montereybayiris.org and browse the pull-down menus. This site also has information about the Society’s meetings and a welcome to membership.

The 11 color patterns of iris blossoms are described and illustrated on the Historic Iris Preservation Society’s web page (historiciris.org/hips-library/iris-color-classes-and-patterns).

Mark your calendar

Gardeners are enjoying a seasonal series of shows and sales by local garden societies. This column has recently highlighted events by the local chapters of the California Native Plant Society, the American Dahlia Society and the Cactus and Succulent Society of America.

There’s more to come. Next week’s column will feature a show co-sponsored by the Santa Cruz Orchid Society and the Santa Cruz Bonsai Kai Club. This event is scheduled for May 3 and 4 at the Capitola Mall (in the space previously occupied by the Sears store).

Enjoy your garden!

Tom Karwin is a past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a past president and lifetime member of the Monterey Bay Area Cactus and Succulent Society and a Lifetime UC Master Gardener (certified 1999-2009). He is now a board member of the Santa Cruz Hostel Society and active with the Pacific Horticultural Society. For garden coaching info and an archive of previous On Gardening columns, visit ongardening.com.