Fall is the perfect time to plant an iris, and they are among the easiest perennials to grow. Named after the Greek goddess of the rainbow, Iris, there are hundreds of iris species in almost all the colors of the rainbow.
Irises come in three forms, rhizome, bulb or root.
The rhizome type iris produce larger flowers and include bearded and beardless type flowers, while the bulb type iris produce smaller flowers are often used in rock gardens or in front row of borders to provide early color in the year. Floral designers use Dutch Iris most often for spring flower designs. Siberian, Louisiana and Japanese iris come in a root form.
Bearded and Beardless.
The bearded iris is identified by thick, bushy “beards” on each of the falls (lower petals) of the blossoms. Most of these types are native to central and southern Europe. Beardless iris does not have the “beard” and mainly originated in Asia.
Decide which type of flower you’d like in your garden, then consult the flowering chart below to pick your perfect iris!
Plant Iris Depending on When You Want Them To Bloom...
- Dwarf Bulbous – Late winter/very early spring
- Dwarf Bearded – Early to midspring
- Tall Bearded – Mid to late spring in general, although this slightly varies per varietes
- Siberian – Late spring to early summer
- Dutch – Late spring to early summer
- Japanese – Early summer
- Louisiana – Early to midsummer
- Reblooming Bearded – Midspring and again in late summer to early fall
Some of the different Iris Varieties available for your garden…
Standard Dwarf Bearded Iris
This is one of the first iris to bloom in the spring and will rebloom again in early – mid fall. These rhizome type iris make nice bushy plants with short, sturdy stems making them perfect for garden edges or borders. These rhizomes are shipped in the summer months of July, August, September and are planted in the fall for an early spring display! When planting the standard dwarf bearded iris rhizomes in the garden, set the rhizome so the bottom half is below ground level and the top half is exposed. Plant where they will get at least 5 hours of sun per day.
Louisiana Iris
Though these beardless iris are native to the Southeastern USA, modern hybrids have improved colors and flower size and are now suitable to be grown in the Northern states too! Hardy to Zone 4, these iris should be planted in fall for a beautiful early to mid-summer flower display!
Tall Bearded Iris
When an Iris flower comes to most people’s mind, they think tall bearded iris. A stately, large, beautiful speciment that dominates the garden or cut flower arrangement. Generally, the first tall bearded iris bloom in the US starting in April and the last ones start their display in June. The blooming period will vary depending on geographic locations. When adding these iris to your garden, plant the rhizome so the bottom half is below ground level and the top half is exposed. Plant where they will get at least 5 hours of sun per day.
Reblooming Bearded Iris
After the main flowering period in spring, rebloomers will bloom again in late summer to fall! The number of blooms you will get later in the season varies on variety and local conditions. Here is how rebloomers work: The rhizome of an iris can produce only one flower stem and it usually takes an entire year to mature and bloom. The reblooming iris has an accelerated growth cycle. Their new growth matures and blooms within the same calendar year. You will generally find the best reblooming to occur in warmer and dryer climates. For example, you will see more reblooming in Zone 8 than in Zone 4.
Planting rhizomes
When planting the reblooming bearded iris rhizomes in the garden, plant the rhizomes with the bottom half below ground level and the top half exposed. Plant where they will get at least 5 hours of sun per day.
Japanese Iris
This stunning iris variety blooms in early summer, about a month after the bearded varieties, and loves to be in moist conditions. They do very well near water (this is where they naturally grow) or where the water table is high. They like the soil to be acidic and do not like to be dried out. The modern hybrids that are now available have very large (up to 7.5″ flowers) which open flat and are available in many different colors. Japanese hybridizers have worked with them for over 500 years.
Siberian Iris
Naturalize your garden with Siberian Iris. These easy-to-grow iris are smaller and more delicate than the large statement flowers. They bloom late spring to early summer which is the perfect time when you need some color before the annuals start to bloom.
Dutch Iris
Grow your own spring flower arrangement with a Dutch Iris. This easy-to-grow Iris grows from a bulb (not rhizome) and can be planted in both fall and spring. These Iris are a florist’s favorite and flower in late spring to early summer. These Iris can be grown in sun or particial shade and are hardy from Zone 3 – 9.
So which will you choose?
Planting Iris this fall will bring easy color and beauty to your garden next spring and early summer!
Information provided by NGB Member Breck’s Bulbs
Find out more about Irises at:
“This post is provided as an educational/inspirational service of the National Garden Bureau and our members. Please credit and link to National Garden Bureau and author member when using all or parts of this article.”
14 comments. Leave new
I live in Austin, Texas. I have Cherry Blossom Song Bearded Iris roots to plant. My understanding is the best time to plant these in this climate is probably September or October – about six months from now. Will the roots keep until then? Under what conditions? If the roots will not keep for six months and I have to plant them now, are there any special procedures for planting now?
Yes, that is the recommended time but to keep them alive, it might be best to plant them now in a shadier location until the fall when you can plant them in the location you desire. Also, you could talk with The American Iris Society for more information
Thank you for the reply. Could I plant the iris roots in pots for now then transfer them to their final location in the fall?
Yes, you can. That would be an excellent idea.
How do I know when to dig up and separate my irises?
Mid to late summer is the time to divide bearded irises. Learn more at https://ngb.org/divideirises
Can I plant bearded Iris under an elm tree? or will the Elm tree kill them?
American elm is somewhat allelopathic, which means it is capable of emitting chemicals that will damage or kill plants competing with the elm for water or nutrients. We would not recommend planting breaded iris under any tree because irises should be planted in a sunny (6-8 hours) location with well-drained soil planted with the top of the rhizomes at the soil or up to an inch below the surface of the ground. Please note that it is difficult to impossible to grow much of anything under any tree, including grass, because of the needs of the tree roots for moisture and nutrients from the soil and because of the shade from the tree.
Can you grow all of these varieties together?
Yes, you can put them all together
I am in zone 9a will they grow here ?
Breck’s mentioned that most of the irises listed are good from Zone 4 – 9.
Thank you. I am an beginning Gardner. I learned a lot .
Thanks for commenting, we are glad we could help.