A Complete Guide To Growing Bearded Irises

Bearded irises boast intricate petals with ruffled edges in pastel hues, making them a showstopper in any garden. My bearded irises grow quite happily without too much fuss. After they’ve bloomed, they can pretty much be ignored for the rest of the growing season. But in high summer (July and August), it’s time to look at them and decide if they’re crowded and need to be dug up and divided. Fortunately, this is a pretty easy task. You’ll end up with more irises to plant elsewhere in your garden or share with friends and family.

Here’s the lowdown on planting bearded irises in your garden, caring for them through the seasons, and many more tips to help them thrive.

Why Choose Bearded Iris for Your Garden?

There are around 300 species of irises, including the ones that are non-bearded. One of the most popular iris varieties, bearded irises (aka German irises) bloom in mid to late spring, depending on the type. The flowers feature three upright petals, called standards and three drooping petals, called falls. Each fall has a tufted beard, hence its name.

Not long ago, bearded irises were mostly found in white, blue, purple and, in some cases, yellow. Most bearded irises grown today are hybrids, with the botanical name Iris x germanica. Hardy in the U.S. Department of Agriculture Plant Hardiness Zones 3 through 9, they come in almost every color.. Many feature bicolored flowers, with falls of one color and standards of another.

Types of Bearded Iris

The American Iris Society classifies bearded irises based on their height, ranging from miniatures only eight inches tall to ones that grow to almost three feet. Bloom times vary from early to late spring. Some, like Immortality and War Chief, re-bloom later in the summer.

Guide to Planting Bearded Iris

Recognizing the best soils for bearded iris, planting them at the right time, caring for its rhizomes and dividing them accurately are all vital for their exquisite blossoms. The step-by-step guide here will take you through the journey.

When to plant bearded iris

Bearded irises are commonly planted from July through September. If purchased as a growing potted plant, they can also be planted in spring. I recommend planting bearded iris in the fall, giving the rhizomes (its fleshy roots) a winter to establish themselves, enabling heartier spring blooms.

Where to plant bearded iris

Choose a location with excellent drainage and full sun. Plant the bearded iris rhizomes in raised beds (at least 6 inches high) to ensure the best drainage and prevent roots from rotting in high moisture.

Bearded irises grow from rhizomes, fleshy underground structures that are drought resistant and rot in wetter soils.

It is best to turn over the soil to loosen it up before planting. Remove weeds. If you have heavy clay soil that doesn’t drain well, add sand and mix it well.

Soaking dry and limp rhizomes in lukewarm water will help a lot. Then, plant the rhizome just below the soil surface, barely covering it with the roots in the ground. Don’t cover it with mulch, which can lead to rotting.

According to the National Gardening Association, bearded irises thrive best in full sun and neutral or slightly alkaline soil. Research also reveals that rhizome rot is preventable by planting at least 12 inches (preferably 1 to 2 feet) apart for proper air circulation.

Fertilizing

Generally, if your soil is healthy and nutrient-rich, you won’t need to worry about fertilizing bearded irises before planting or once they’re established. But if you notice your irises are struggling to bloom, it could be worth doing a soil test to see if your soil lacks nutrients and apply a general fertilizer before planting.

Watering

Established irises generally do not need additional watering and will even tolerate periods of drought. Water well after planting, but make sure the irises aren’t standing in water.

Deadheading

Pinch off faded, withered flowers from the plant. This helps in checking/curtailing nutrient wastage. Pruning in time helps flowers bloom.

Also, after your bearded irises have flowered, cut off the flower stems to encourage the plant to grow stronger rhizomes instead of seeds.

Preventing Bearded Iris Pests and Diseases

Bearded irises are not bothered by many pests or diseases, except for one—iris borers.

Inspect your irises in spring and summer for signs of iris borer caterpillars. According to the University of Minnesota Extension, these first chew holes in the leaves, then burrow down into the rhizomes. Check for brown streaks on the foliage.

If you find the borers on the leaves before they reach the rhizomes, crush them in the leaf or cut off that leaf to destroy them. If you find iris borers in the rhizomes, dig those up and discard them.

To break the borer’s life cycle, cut back and dispose of all iris foliage after the first fall frost. This simple, chemical-free practice helps keep iris borer populations in check and protects your plants in an environmentally responsible way.

Planting Bearded Iris Tips

• Building raised garden beds helps keep the soil drained and dry.
• The Bearded Iris Rhizome should not be planted too deep.
• Good drainage and full sunshine work best for the plant.
• Overwatering will destroy the roots so will over-fertilizing.
• Overcrowding of plants disrupts the free fall of sunshine.
• Caution and care: Bearded Irises can be toxic for pets, mostly cats or dogs.

Dividing Irises for Healthy Blooms

As mentioned above, the best time to dig and divide bearded irises is a month or two after flowering, usually July to August. Healthy bearded irises will generally get crowded after two to three years in the same spot. Then it’s time to divide them.

Dig up the entire clump of irises at one time. You will find several new rhizomes attached to the older or original rhizomes. Carefully separate those so you end up with at least one fan of the spear-like leaves and roots attached to each rhizome.

Dividing irises is important for healthy blooms. Cut the leaves back, leaving them about six to eight inches long, then replant the new rhizomes. Old rhizomes can be discarded. Save your extras if you have more rhizomes than you want to replant.

FAQs

Can bearded iris be grown in pots?

It’s not very common, but you can definitely try. Ensure that the pot is at least 12 inches wide and follow all other planting instructions given above.

Is the bearded iris climate resilient?

Yes, bearded iris is a hardy plant, drought-resistant, needing very little maintenance and can withstand mood swings in temperatures. The only thing it cannot withstand is excess moisture in the soil.

The plants are so hardy and persistent that they can grow on their own in old abandoned houses.

Which plants go best with bearded iris?

Some great companion plants for bearded iris include Oriental poppies, lupine, allium, delphinium, baptisia, peonies, daylilies, and salvia. These perennials complement iris in both bloom time and form, creating a visually dynamic and seasonally balanced garden.

Sources

• Nicolas Stocken: “Bearded iris are late spring’s most flamboyant flowers. Find out how to grow these frilly, flouncy border stars”
• Longfield Garden: “All About Bearded Iris”
• Cooperative Extension, University of Arizona: “Backyard gardener”
• University of Minnesota Extension: “Iris>Holes in Leaves”
• American Iris Society: “Bearded Irises”
• National Gardening Association: “Planting Bearded Iris”