Highlight of the iris cycle - Santa Cruz Sentinel

ON GARDENING

Highlight of the iris cycle

Big Picture (Ghio 2015) Glorious bicolor with domed standards of light pink with deeper midrib. The broad semi-flaring falls are red purple with a thin violet rim with a big pink sunburst highlight the falls. Styles are also pink and tangerine beards. Big wavy ruffles undulate around the petal edges. Wide show branching. PHOTOS COURTESY OF TOM KARWIN

Carousel of Dreams (Richardson 2014) Midseason to late bloom. Standards and style arms pale lavender, thin gold rim; falls dark red, gold rim, pale sunburst pattern at beards; beards gold-orange; slight sweet fragrance.

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The annual sale of iris rhizomes is coming soon! This event, hosted by the volunteers of the Monterey Bay Iris Society, provides an excellent time to add irises to your garden.

We provide specifics of the sale below, but we begin with an overview of the annual cycle of this favored genus of garden flowers.

Today’s photo gallery displays my photos of selected blossoms of irises grown in the Monterey Bay area. These photos were taken at a local garden. Another photo shows judges, assisted by volunteers, comparing blossoms at an April show organized by the Monterey Bay Iris Society.

Introducing this exceptional plant

The Iris genus is a member of Iris plant family (Iridaceae), which includes 66 genera, including the familiar freesias, gladioli and crocuses. The Iris genus includes about 300 species. Taxonomists have organized these species into several sub-genera, each of which contains numerous species. The genus includes three broad categories: bearded, aril and beardless irises.

Bearded irises are characterized by bushy, hairy growths (“beards”) on their lower petals. This highly popular group includes some 30,000 hybrids. They are available in different heights: Miniature Dwarf Bearded (MDB), Standard Dwarf Bearded (SDB), Intermediate Bearded (IB), Border Bearded (BB), Miniature Tall Bearded (MTB) and Tall Bearded (TB).

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 (SPU), Siberians (SIB), Japanese (JI) and Louisianas (LA). Other groups of beardless irises are the Pacific Coast Natives (PCN), which are native to America’s West Coast, and the Species irises.

The popularity of irises

Irises are one of the most highly favored genera of garden flowers because of compatibility with the Monterey Bay area climate, easy cultivation, and a wide range of plant forms and blossoms colors. They also perform excellently as cut flowers.

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, where the top three petals (“standards”) are one color, and the bottom three petals (“falls”) are often another color. For more on this topic, visit the website tinyurl.com/bd36mxd6.

Growing irises

Nearly all species of the genus Iris grow readily in the Monterey Bay area, where the climate is compatible with the plant’s natural range: temperate Northern Hemisphere zones from Europe to Asia and across North America.

Members of the Iris plant family are perennial plants, with a bulb, corm or rhizome. The plants grow erect, and have leaves that are generally grass-like, with a sharp central fold.

Most popular Iris species are grown from rhizomes. These are not roots but specialized stems. Plant them horizontally with their top surface exposed to light and air.

Rhizomes should be planted where they will receive at least six hours of sun each day. Amend the soil by digging in a generous measure of compost or well-rotted manure, plus a handful of bone meal for each planting hole.

If you have plenty of space and will leave the plants in place for several years, space the rhizomes two or three feet apart. If you have limited space and want a full clump in the spring, plant three rhizomes in a triangle with eight-inch sides. Orient the fans away from the center of the triangle to direct the plant’s growth outward.

Water the plant well and allow the top of the soil to dry out before watering again.

Label your plants and map their locations as a backup. Do not rely on your memory!

Iris plants develop their peak blooms in late spring, providing a colorful display in the garden.

Iris shows are scheduled usually in April to provide opportunities for growers to display the results of their careful cultivation, for the sponsoring societies to promote interest in the plant genus, and for gardeners to both observe high-quality specimens and identify varieties to add to their own gardens. Today’s pictures include a show photo.

Propagating Irises

The July to September window is the plant’s dormant period: the time of the year to divide and transplant your irises.

Irises should be divided after three years of growth in the same location. Dividing the plant increases the growing space for each rhizome, and thereby promotes blossoming.

Division also provides opportunities to move your irises to new locations in the garden or share rhizomes with friends.

Begin by digging up the plant. The tool of choice is a garden fork, but a spade also will work.

Iris rhizomes are usually close to the surface so deep digging should not be required. It is important to avoid damaging the rhizomes. To be safe, dig and lift about a foot away from where you think the rhizomes are growing and move around the plant until you can pull it up by the leaves.

Shake off the loose soil and hose off the remaining soil. You may also trim the roots for easier handling.

Inspect the rhizome for any signs of rot or insect damage. You might well find no such problems, just a healthy cluster of rhizomes. If you do find minor damage, cut away the affected parts with a sharp knife and dispose of them. The rest of the rhizome will grow. A good practice is to clean the knife between cuts with a bleach solution or denatured alcohol.

If you are digging several plants and wish to keep track of their cultivar names, take care to keep the plants together with their nametags and separate from each other.

The next step is the actual division of the rhizome. You should see new rhizomes growing out of the original rhizome. Separate the rhizomes by snapping them off (the easy way) or cutting them with a knife. Each rhizome ideally will have a fan of at least three leaves. The original rhizome has served its purpose and can be discarded.

Write the name of the cultivar on the middle leaf of each rhizome with a permanent marker. If you have lost track of the plant’s cultivar name, you might still wish to mark the blossom color.

You can replant the rhizomes immediately or store them in a cool, dry place until a convenient time. Plant them by the end of September or early October to support spring blooming.

The full leaves can be left on the plant in storage, but when ready to plant, cut the foliage to about six inches long. This makes the plants easier to handle and reduces water loss through transpiration.

A good practice is to soak the rhizomes for 15 minutes in a 10% bleach solution to eliminate any possible disease. After soaking, rinse the rhizomes in clean water and air-dry them before replanting.

Iris rhizome sales

The time for gardeners to propagate their Iris plants is also time to share rhizomes with other gardeners. The Monterey Bay Iris Society convenes its annual rhizome sales so that its members can share rhizomes efficiently and all gardeners can select from an impressive collection of rhizomes to add irises to their gardens.

Commercial growers of irises also distribute their rhizomes at this time of year through mail order sales and local garden centers.

The Monterey Bay Iris Society will present its Annual Iris Sale from 9 a.m. to noon Aug. 3 (or sell out). The event will be held at the Deer Park Shopping Center, in the courtyard in front of the Red Apple Café.

The society will present two follow-up sales at the Cabrillo/Aptos Farmers Market. These events will be from 8 a.m. to noon Aug. 10, and 8 a.m. to noon Aug. 17.

The event will include irises of different heights, as defined above: MDB, SDB, IB, BB, MTB, and TB. Gardeners could select varieties to complement their garden designs.

The sales will display attractive photos of blossoms to support purchase selections. These pictures enable gardeners to appreciate the blossoms and select color combinations that will enhance their gardens.

Enjoy irises in 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 & 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. To view photos from his garden, https://www.facebook.com/ongardeningcom-5665117 63375123/ . For garden coaching info and an archive of On Gardening columns, visit ongardening.com for earlier columns or visit www.santacruzsentinel.com/ and search for “Karwin” for more recent columns. Email comments or questions to gardening@karwin.com.