Some Good Grooming Hints for Bearded Iris
In August, even die-hard gardeners are more likely to be thinking about iced tea than bearded iris. But this is the month to buy, plant and divide these pretty perennial plants with a Mediterranean past.
The parents of today’s bearded iris came from that area with a climate so similar to our own. Iris florentina , the misnamed I. germanica and other relatives still grow wild in the dry hills of Spain, Provence and Tuscany.
They follow a cycle very similar to our own native plants, blooming in early spring, growing during spring and early summer and then going almost dormant until fall when the winter rains return. In California, tall bearded iris flower during a seven-week period in late March and April, do most of their growing in May and June, then become semi-dormant in July, August and September.
That is the best time to move the sweet-potato-sized rhizomes, so growers dig their plants and send them to nurseries, and hobbyists plant or divide old clumps. August and September are the busiest months in an iris fancier’s year, and it is just about the only time you will find the rhizomes at nurseries.
Tall bearded iris have been out of fashion for a while, but their Mediterranean ancestry and proven drought resistance is bringing them back. Gardeners appreciate their strong, vertical, sword-like foliage--a good accent in a garden of mounded forms, and the tall flower spikes stand well above other flowers--an exclamation mark in spring.
Modern bearded iris seem to remember the dry, warm summers of their native lands and in California are ridiculously easy to grow. Bearded iris are called “tall” when they have flowering stems 27 inches or taller. Many are much taller, to four feet or so.
The beard that gives them their name is the little fuzzy part in the middle of the flowers, between the upper petals called “standards” and lower called “falls.”
Those with large clumps of bearded iris that no longer bloom as they did should get the spade out and start digging right now. Tall bearded iris need dividing, about every three years.
“Just when a clump really looks good, it is time to divide,” said Jim Puckett, who grows thousands of irises at his Blooming Fields Farm in Riverside. “If you wait another year, you will regret it. Flowering drops off dramatically when the clumps become crowded.”
Save only the larger, healthier rhizomes with healthy root systems, from the outer edge of the clump. These are the most likely to bloom next spring. Shake the soil from the roots, trim the foliage so it is about six inches long (to compensate for the loss of any roots) and then carefully replant. It’s a good idea to add a little amendment and fertilizer to the soil before replanting.
Plant in small groups of three. The growing tips (with the leaves) should face out and there should be four to six inches between the ends or “toes.” Plant several such clusters of three, spacing each cluster about 12 to 18 inches apart in a random pattern. This arrangement will make a new clump that looks as if it has been undisturbed for years, and it allows for some room to grow.
Water the new planting and they will begin to grow new roots. The roots will grow until winter when the plants go briefly dormant. New leaves will follow, with flowers in spring.
Puckett says the August timing is critical because the new plants need six weeks to grow roots before going dormant.
Planting the rhizomes that are available at nurseries now is very similar. Bearded iris like a well-drained soil, so you should add amendments. If your garden soil is a heavy clay, Puckett recommends amending it and gently mounding it (to a height of two to three inches), to speed the drainage.
Plant the rhizomes so the top is right at the soil surface. The very tops are normally exposed.
You can plant just one of each kind, and wait a few years for them to multiply, but they are more dramatic in drifts of at least three of the same kind.
Water the plants every week to 10 days until they are established in the garden. The following summer back off on the watering after July, so the plants can go a little dry. In Puckett’s care instructions, BE SURE NOT TO OVERWATER is in capital letters.
Bearded iris will grow in shade but don’t expect them to flower. Fertilize lightly in February and fall. Most bearded iris go dormant in winter and you should cut or gently pull off the shriveled, tan leaves. Keep after the weeds that are sure to sprout between the rhizomes.
Because the climate is ideal--as one early hybridizer quaintly put it, “the climate of California is the envy of iris cranks the world over”--there were once many iris growers in the state. Most moved on when land prices skyrocketed in the 1950s, but Puckett is determined to bring the iris business back and offers several lists: a “Minicatalogue,” “Newer Iris Varieties, 1991-1981,” “Proven Performers, ‘70s and ‘60s,” and “Antiques and Classics, 1963 and earlier.” Write to Blooming Fields Farm, P.O. Box 8416, Riverside, Calif. 92515.)
Puckett takes his blooms to nurseries and flower shows in spring, so people can see what they look like, and accepts orders then (he can send you a schedule), but the rhizomes aren’t shipped until July and he stops digging in September, when the window of opportunity for planting or dividing iris slams shut.
Planting Irises
August is the best time to plant new rhizomes or divided old plants because it allows several weeks of growth before the plants go dormant for the winter. When dividing, save only the larger rhizomes with healthy root systems, usually at the outer edges of the clump. Shake the soil from the roots trim the foliage as shown and carefully replant. It’s a good idea to add a little amendment and fertilizer the soil before replanting.
Planting Depth Plant each rhizome so that the top is right at the soil surface. The very top of the rhizome is normally exposed. If you are planting in heavy soil, use an amendment and mound gently to promote good drainage. Water every week to 10 days until plants are established. After that, take care not to overwater.
Rhizome Groupings Plant in groups of three. The leaf ends should face outward, 4 to 6 inches apart. Plant several such clusters in a random pattern about 12 to 18 inches apart.
