Bearded iris grows best in sandy or well-draining soil conditions with full sun exposure and is somewhat drought tolerant.
These plants are toxic to dogs and cats.
Bearded irises have a moderate growth rate, growing 4 to 40 or more inches in one year.
Terre de Feu IrisEve Livesey/Getty Images
Where to Plant
Give bearded irises full sun to grow and well-draining soil.
Iris plants can’t tolerate clay-like soils.
They can tolerate all-day sun in cooler climates, such as in the lower USDA zones 4 and 5.
Panama Hattie IrisEve Livesey/Getty Images
How to Plant
Plant the rhizome rooting structures about 1 to 2 feet apart.
They do not need to be planted too deep.
Mostiris rhizomesshould be planted below the surface, exposing the top with any roots pointed downward.
Lightly water to settle the soil around the root structure.
Tall bearded irises require staking, especially during high winds or inclement weather.
A major departure for growing irises compared to other perennials is that they do not like mulch.
Mulches (as well as deep planting) encourage therhizomesto develop rot, so let your soil remain bare.
Space plants at least 12 inches apart to prevent the need for frequent dividing.
In full shade, they produce fewer blooms and may suffer from an increase in diseases.
If your native soil is heavy, you canplant your iris bulbsinraised bedsto help drainage.
To lighten the soil, you may also amend your soil with gypsum or organic matter like compost.
Water
Although irises like moisture, they also need good drainage to prevent rot.
Water them when the top 2 inches of the soil feel dry.
These plants have a good drought tolerance.
Temperature and Humidity
Irises are notorious for their hardy disposition.
They don’t mind temperature extremes if the soil allows excess rain or snowmelt to drain away.
Irises damaged by heavy winds or hail can be susceptible to iris borer larvae.
Fertilizer
In the spring, apply a low-nitrogen 6-10-10 fertilizer around your irises.
Too much nitrogen will encourage foliage at the expense of blooms.
Bone meal is also agood fertilizer.
“Japanese, Dutch, andSiberian irisare among those that fall into the beardless category.
There are also subcategories based on stature and varying bloom times.
Dividing will keep iris plants vigorous and allow you to propagate new plants.
Propagating Bearded Iris
Dividing irises every few years keeps them healthy and multiplying.
Dig up the rhizomes with a shovel in late summer and shake off all loose soil.
Cut away soft, rotten parts of roots or areas that have borer tunnels or worms.
Water thoroughly upon planting, then weekly until frost sets in.
Most garden iris are hybrids, and usually do not “come true.”
The iris plants you propagate by collecting seeds may look quite different from the mother plant.
Do not overwater the plants.
In colder climates, move the containers to sheltered locations for the winter.
Irises in containers may needdividing and transplantingabout every other year.
Destroy the removed foliage but do not add it to a compost bin.
If plants show signs of rot or damage from borers, dig up the roots in early fall.
Cut away diseased or worm-damaged sections and replant the healthy roots several weeks before freezing weather sets in.
The iris borer is a serious pest.
Major disease problemsinclude bacterial soft rot, crown rot fungus, and fungal leaf spot.
Mottled leaves and flowers suggest the mosaic virus.
Remove and destroy affected plant material (do not compost).
Good hygiene is usually enough to control these diseases; fungicides aren’t usually needed.
Some reblooming cultivars may rebloom in summer or fall.
What Do Bearded Iris Flowers Look and Smell Like?
Bearded iris flowers are known for their large, show-stopping flowers.
They have six petalsthree upright standard petals and three floppy petals that fall downward.
The petals have a central, bearded line leading inward to the flower center.
Of the irises, bearded irises are the most fragrant.
Some cultivars are more fragrant, with scents ranging from orange blossom to grape soda.
Bearded irises are largely trouble-free but can develop a few issues.
Irises that grow in shady conditions may get even leggier, making staking a necessity.
Leaves Have Yellow and Brown Spots
Spotted leaves are the result of bacteria or fungal infections.
Bacterial leaf spot usually begins on the edges of the leaves, gradually enlarging.
Affected plant parts should be removed and destroyed.
Keep the ground around the irises free of mulch and debris.
Good garden hygiene usually controls leaf spot diseases.
Serious fungal infections can be controlled with fungicides.
Yes, a bearded iris will grow new rhizomes and multiply on its own.
Late summer is the best season to divide bearded iris.
This gives the plants enough time to settle in before the first frost.
AIS Dykes Medal Winners.Historic Iris Preservation Society.
