Bearded Iris Growing Guide

By: Sherri Ribbey

Keep spring colorful from start to finish with bearded iris. Learn about different varieties, how to plant, divide and more in this growing guide.

How to grow bearded iris

If you want nonstop color for spring, look no further than bearded iris. Though it's easy to grow, there are a few details that will ensure your plants comes back and look gorgeous year after year

Bearded iris do best in full sun for lots of flowers and well-drained soil so the rhizomes don’t rot. For strong plants, fertilize with a low-nitrogen plant food in early spring and again a month after they finish blooming.

Planting bearded iris rhizomes: Keep rhizomes at soil level to prevent rot. Spread the roots out and firm the soil to keep the iris in place until it gets established.

Planting bearded iris rhizomes

Whether you see a pretty potted bearded iris you like at the garden center in spring or buy from a mail-order company that ships the rhizomes to you in summer, the rhizomes should be planted at or just below the surface of the soil to prevent rot. Plant rhizomes 1 to 2 feet apart with the smaller iris types closer together than the larger ones. This allows enough space so you don’t have to divide in a couple of years.

Dig the right size hole

To plant bearded iris dig a shallow hole and use some of the soil to build a small hill in the center. Place a rhizome on top of the hill of soil with the roots spread apart and the rhizome at soil level, then fill in the hole, covering the roots and firming as you go to keep it anchored. It’s OK if some of the rhizome shows above the soil, as it does in the photo above. Give your new plants a thorough watering and then don’t worry about doing so again unless it’s a dry year — up to 1 inch of rain a week is fine for bearded irises.

Deadheading bearded iris technique: Deadhead bearded iris using pruners or scissors to remove each flower as it fades (left) and the entire stem when they’re all done (right)

Deadheading bearded iris

Bearded irises start blooming at the top of the stem and move down, with each flower lasting for 2 to 3 days. You can snip off individual spent flowers as they fade if you’d like, but you’ll want to cut the long stem back to the foliage once all the blooms are done to tidy up.

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summer-garden-checklist-divide-bearded-iris: Some rhizomes, like those above, pull or break apart easily.

Dividing bearded iris

If you’ve noticed your bearded irises aren’t blooming like they used to, they may need to be divided — every 3 to 5 years on average. Fortunately, it’s easy to do. The best time to divide bearded iris is 6 to 8 weeks after blooming or sometime in summer. Plants are partially dormant this time of year so the growth of roots and foliage has slowed down.

Dig the clump of rhizomes out of the soil.
Cut the foliage back to 10 to 12 inches to make handling them easier.
Break the rhizomes apart into smaller pieces, as I’m doing above.
Remove the oldest pieces, which don’t have foliage.
Get rid of any rhizomes that are dried out or rotten.
Replant the rhizomes in the same way you plant new ones and water well.

iris borer and leaf spot on bearded iris: Iris borer and leaf spot are two problems that bearded iris may be suceptible to.

Troubleshooting bearded iris

Bearded irises have few problems, but there are a couple common ones that may crop up: iris borer and leaf spot. They don’t kill your plants right away but weaken them over time until they finally die. One practice that keeps bearded irises healthy is getting rid of the foliage in late fall. Cut leaves back to the rhizome or tug away dried or tired-looking leaves and burn, bury or send them away in the trash, especially if you’ve noticed any problems over the growing season.

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Bearded iris types comparison illustration by Carlie Hamilton

Types of bearded iris

You may be surprised to know that there’s more to bearded irises than the tall varieties. Look over the chart above to see how they're broken into six groups based on bloom time, plant height and flower size. They all have the same care needs so it’s easy to combine them for weeks of beautiful flowers (even months if you include a few rebloomers from each group). In general, the larger the plant, the later in spring it blooms. (When you're browsing catalogs you might see the acronyms listed in parenthesis with each name listed below.)

Minature dwarf bearded iris (MDB) 4 to 8 in. tall
Standard dwarf bearded iris (SDB) 8 to 16 in. tall
Intermediate bearded iris (IB) 16 to 27.5 in. tall
Minature tall bearded iris (MTB) 16 to 27.5 in. tall
Border bearded iris (BB) 16 to 27.5 in. tall
Tall bearded iris (TB) 28 in. and up

Bearded Iris anatomy illustration by Carlie Hamilton

Bearded iris anatomy

Before browsing the gallery below it’s helpful to know a little bearded iris lingo. The illustration shows you the basic parts of an iris flower, fall, standard & beard, so you'll be "in the know" when you read the catalog descriptions.

‘Icon’ miniature dwarf bearded iris (Iris hybrid)

‘Icon’ is a diminutive iris that looks best planted in groups of five or more to for a bright spot of color. Within 2 to 3 years it will spread to form a good-sized clump. While most bearded irises flower best in full sun, minature dwarf bearded (MDB) do just fine even with some afternoon shade — 4 to 6 hours of sunlight is enough for plants to remain healthy and flowering.

Type Perennial Blooms Golden orange standards with wine-purple falls and an mandarin red beard in early spring Light Full sun to part shade Soil Well-drained Size 8 in. tall Hardiness Cold hardy in USDA zones 3 to 9

‘Lakota’ intermediate bearded iris (Iris hybrid)

Give light-colored intermediate bearded iris ‘Lakota’ a backdrop of evergreens or other dark foliage and its blooms will really shine. This one is a plicata, which means the flower has stippled, dotted or stitched edges. In some cultivars the pattern is more obvious than you see here.

Type Perennial Blooms Lavender standards with peachy-orange falls that have a purple center and orange beard in early to midspring Light Full sun Soil Well-drained Size 23 in. tall Hardiness Cold hardy in USDA zones 3 to 9

‘Bundle of Love’ border bearded iris (Irishybrid)

‘Bundle of Love’ is a border bearded iris (BB). This type looks a lot like the tall bearded iris but is smaller. It competes easily in a crowded border, blooming up a storm along with the tall bearded iris and other spring perennials, such as peonies and lupines.

Type Perennial Blooms Buff pink to creamy standards and falls in midspring Light Full sun Soil Well-drained Size 26 in. tall Hardiness Cold hardy in USDA zones 3 to 9

‘Cherry Garden’ standard dwarf bearded iris (Iris hybrid)

‘Cherry Garden’ has red-violet standards and falls and blue-violet beards. Since both standards and falls are the same, the flower color is called a self. This cultivar grows so well, blooms so profusely and is such a good example of what an standard dwarf bearded iris (SDB) should look like that it received the CookDouglas award in 1970, which is given annually by the American Iris Society to a top-performing standard dwarf bearded iris.

Type Perennial Blooms Red-violet blooms in midspring Light Full sun Soil Well-drained Size 8 to 12 in. tall Hardiness Cold hardy in USDA zones 3 to 9

‘Little White Tiger’ miniature tall bearded iris (Iris hybrid)

As intermediate bearded irises start to fade, the miniature tall bearded irises, such as ‘Little White Tiger’ get going. It has a dainty look with thinner branched stems and smaller flowers than other types. These petite blooms are great for cutting — they won’t tip over a slender vase and are easy to work into a bouquet without overpowering the group. And they have a light fragrance.

Type Perennial Blooms White standards with purple veined falls and a yellow beard in midspring Light Full sun to part shade Soil Well-drained Size 16 in. tall Hardiness Cold hardy in USDA zones 3 to 9

‘Blueberry Parfait’ tall bearded iris (Iris hybrid)

‘Blueberry Parfait’ is a big plant with bright white and purple ruffled blooms making it a great focal point or for drawing attention to a special place in the garden. This tall bearded iris (TB) variety is known for producing numerous flowers on each stalk, perfect for bringing lots of spring color to large spaces or as a mass planting.

Type Perennial Blooms Heavily ruffled white standards and white falls with a purple edge in late spring Light Full sun Soil Well-drained Size 36 in. tall Hardiness Cold hardy in USDA zones 3 to 9