There are over 300 species in the genus. The one most familiar to most of us is the tall (at least 28 inches) bearded iris. It’s the royal standard (fleur-de-lis) of France, and is also the symbol of Florence, Italy.
These exotic-looking flowers have three large outer petals called “falls” and three inner upright petals called “standards.” The falls have beards or crests. Bearded iris are called this because of the soft hairs along the center of the falls. In crested iris, the hairs form a comb or ridge. Depending on where you live, your irises will flower in early-to-mid spring or early summer. Some, mostly hybrids of the bearded type, will bloom again in late summer. The photo below is of a re-blooming type:
Irises Have Only a Few Needs, But they Do Need Those Things:
- Irises need at least half a day (6 hours) of sun, and well-drained soil. Without enough sun, they won’t bloom. Bearded irises should not be shaded by taller flowers or shrubs. Because of this, they don’t make good understory plants; and they will do best in a special bed is reserved just for them.
- They prefer fertile soil, with a neutral to slightly acidic pH. If your soil is very acidic, sweeten it with a bit of lime. The soil here in central Florida is on the alkaline side, so I have to increase the acidity of my soil. I do this by mulching around them with pine needles and used coffee grounds.
- Irises are drought tolerant so, of course, they don’t like wet feet, which can lead to rot. Because of this, good drainage is very important for any drought tolerant plant.
Planting Bearded Irises:
The best time to plant irises is anytime between July and September.
- Loosen the soil to a depth of about 12 inches, then mix in 2 to 4-inches of compost.
- Bearded irises have rhizomes (fleshy roots) that should be partially exposed, or thinly covered with soil in hot climates.
- Plant rhizomes singly or in groups of three with the fans toward the outside of the group, and 1 to 2 feet apart, depending on the size.
- Dig a shallow hole 10-12 inches in diameter and 3-to-4 inches deep. Make a little ridge of soil in the middle and place the rhizome on the ridge, spreading the roots on both sides. Fill the hole with soil and gently press until it is firmly in place, and and water thoroughly.
- Avoid applying high-nitrogen fertilizers, as this will result in lush leaves, but will not help the flowers.
- Avoid mulching on top of the rhizomes with organic matter, which will encourage rhizome rot.
- Keep rhizomes exposed. The should look like little potatoes laying on the ground. Unlike bulbs, which prefer to be deep underground, iris rhizomes need sun and air to dry them out, especially after a lot of rain. If covered with soil or crowded by other plants, they will rot.
Care After Blooming Is Finished:
- Remove the spent flower stalk at the point where it emerges from the plant to discourage rot.
- Resist trimming iris leaves after they have finished blooming. They need to be able to draw nutrients from their leaves for next year’s growth.
- Remove any brown leaves.
- In late summer or early autumn, do what is called “fanning” the leaves by trimming the (usually ragged) leaves so that the part remaining resembles a fan. The photo of the leaves shows an iris that is being transplanted. The baby irises will be removed and planted separately. The “fan” of leaves will be trimmed to about 6 inches. This should be done whether or not you are moving the plant.
When Irises Become Crowded:
- One is to dig up the entire “family”, then break off the pups, and plant them each at least one foot apart.
- If you are pressed for time, another method is to use a shovel or a sharp knife to cut out the mother plant, while leaving the group in place. This will help for no more than a year or two. Then the fully grown pups will need to be moved farther apart, as they will have begun having pups of their own.