A friend was amazed as she looked at my perennial bed in late October of two years ago and said, “That flower looks just like an iris!” And indeed, it was Iris St. It was a beautiful tall bearded hybrid with violet-tinged white standards and falls. It bloomed in the spring, like most garden irises do, but then it bloomed again in the summer and fall. More and more gardeners are buying iris that rebloom, also called remontant irises, because they can make one of their favorite plant groups flower for a much longer time. Iris enthusiasts can also seek out species and cultivars that bloom naturally into the summer.
The iris is a well-known garden plant that is loved for its straight shape and bright, unusually shaped flowers. But the taxonomy is hard to understand, and it’s always a good idea to go over the terms before talking about irises. In brief, iris flowers consist of three upright petals (standards) sitting atop three larger, usually pendent sepals (falls). The Iris genus is large, with over 250 species and many, many cultivars. Horticulturists put all of these into groups and subgroups based on things like rootstock type (rhizomatous vs. bulbous), where the plant came from, its size, its culture, and whether or not it has colored hairs (beards) in the middle of the falls.
The remontant irises are primarily hybrids of plants in the bearded iris group. Bearded rebloomers of all sizes have been registered with the American Iris Society over the past five years. Breeders have been making them like crazy lately. Here are some plants that bloom all year, some that only bloom once in the spring and then again in the summer or fall. Find remontant irises that are known to do well in your area when you are shopping for them. (Contact your local iris society for recommendations; see “Iris Resources. “) Thats because along with genetic factors, climate and culture are also important for reliable reblooming.
For gardeners interested in naturally late-blooming irises, choices abound. A number of bearded varieties bloom from early spring to early summer. Among beardless irises, many varieties in the Spuria subgroup bloom from late spring to midsummer. Some Siberian iris (Iris sibirica) and Japanese iris (I. ensata) selections bloom from mid-spring to early summer. Beardless southern blue flags (I. virginica) bloom into early summer. Bulbous irises in the Xiphium subgroup—including Dutch, Spanish, and English irises—flower from mid-spring to midsummer.
Few perennials add as much reliable color to garden beds and borders as irises do, in both bright and soft shades. The remontant and late-blooming cultivars allow us to enjoy this color throughout much of the growing season. As with other garden irises, they range in size from tiny dwarfs to giants over four feet tall. The taller types look great as background plants in perennial borders, and the smaller types look great as edges around the front of flower beds.
When it comes to site, there are irises that will grow in almost any type of soil, from sandy (bearded irises) to wet (Japanese irises). Xiphium, Pacific Coast, and Siberian irises thrive in soil that is kept moist. The miniature bulbous irises (Iris reticulata and I. danfordiae) require excellent drainage and are thus good candidates for rock gardens. Most irises prefer full sun or light shade and adapt to a wide range of temperature zones.
Following is a selection of some of my favorite remontant and later-flowering iris cultivars. In my garden in Missouri (USDA Zones 5 to 6), all of the remontants reliably bloom again, usually in late summer or fall, depending on how hot it was in the summer. If you want to get more from your perennials, give them a little extra water and fertilizer, especially after the first bloom. Deadheading spent flowers also encourages repeat bloom. Most irises do best when planted between the middle of summer and early fall, but plants can be put in pots whenever the soil is loose enough to work.
Autumn Tryst is a tall bearded cultivar that grows back to life. It is 2½ to 3 feet tall and has fragrant white flowers with rosy lavender edges. Hardy from Zones 3 to 10, it grows best in full sun and medium-moist soil. The first blooms appear in May. Autumn Tryst is a good choice for mixed perennial beds.
This remontant standard bearded dwarf (SDB) can grow in Zones 3 to 10. It has yellow flowers on 8- to 15-inch plants, first in the spring and then at different times during the season. It can handle more shade and a wider range of weather conditions than other bearded irises, just like other SDBs. Baby Blessed is a good choice for edges of border beds.
This tall bearded iris won the prestigious Dykes Medal. It grows 2½ to 3 feet tall and has many flamingo-pink flowers with flaring falls in June. Hardy from Zones 3 to 9, it does best in full sun and medium-moist, well-draining soil. Beverly Sills is very effective when planted in masses.
Gardeners love iris for their stunning blooms and sword-like foliage that adds striking vertical accents. While bearded iris typically bloom in spring, some varieties rebloom in summer and fall, extending the floral display. Certain iris species also bloom repeatedly through the season. Discover how to have non-stop iris color from early summer into fall.
Why Grow Summer Blooming Iris
Most bearded iris bloom heavily for just 2-3 weeks in spring Then the spectacular floral show is over until next year Summer blooming iris provide the following benefits
- Prolonged color in beds, borders and containers
- Gorgeous cut flowers over months instead of weeks
- Fragrance late into the growing season
- Consistent rebloom without special care in warm climates
- Handsome iris foliage all season even when not in bloom
Reblooming iris and remontant iris give multiple blooms on the same rhizomes within a single growing season. Once the spring blooms fade, new bloom stalks emerge in late summer and fall.
Best Iris for Summer Long Bloom
Several iris species and cultivars can bloom repeatedly through the warm season
Bearded Iris Rebloomers
Many modern bearded iris hybrids rebloom if grown in zones 7-9. Some top repeat bloomers include:
- Autumn Circus – Ruffled white and blue
- Sugar Blues – Blue with orange beards
- Jesse’s Song – White heavily stitched violet
- Pink Attraction – Light pink with orange beards
- Best Bet – Light blue standards, hyacinth blue falls
Iris Sibirica (Siberian Iris)
This tough, adaptable iris blooms from spring into summer. Cultivars like Caesar’s Brother and Butter and Sugar produce flowers for 6-8 weeks. Cut back spent blooms to encourage rebloom. Varieties with blue, purple, white or yellow blooms reach 2-4 feet tall.
Iris Germanica Florentina
The old white flowering iris blooms in late spring, takes a short break, then reblooms into summer. It reaches 2-3 feet tall and tolerates drought when established. The elegant white blossoms also make exceptional cut flowers.
Iris Louisiana Hybrids
Louisiana iris bloom heavily in spring, take a short rest, then rebloom from summer into fall. They thrive in hot humid climates. Cultivars like Cajun Sunrise and Electric Night rebloom reliably into fall.
Dutch Iris
Though not true rebloomers, these early spring bloomers provide color again in early summer. Place them near summer bulbs like agapanthus and lilies for continuous bloom. Popular varieties are Blue Magic and Yellow Falls.
Where and How to Plant Summer Blooming Iris
Follow these tips to successfully grow iris for non-stop flowers:
- Plant in full sun – at least 6 hours of direct sun daily.
- Choose well-drained soil enriched with compost. Raised beds work well.
- Space rhizomes 12-24 inches apart depending on mature clump size.
- Set the top of the rhizome at or just above soil level.
- Water weekly until established, then as needed during droughts.
- Apply balanced fertilizer in early spring and again after spring bloom.
- Mulch around iris to moderate soil temperatures and retain moisture.
- Prune spent blooms and faded foliage as needed to tidy plants.
- Divide congested clumps every 3-4 years in mid to late summer.
Reblooming iris should begrown in zones 7-9 for best results. In colder climates, try planting in awarm microclimate, like against a south facing wall. Protect iris from frigid winter winds.
Encouraging Rebloom in Bearded Iris
To coax repeat blooms from bearded iris in summer and fall:
- Choose named reblooming varieties rated for your zone.
- Give iris a very sunny exposure with at least 8 hours of sun.
- Keep plants actively growing all season by watering 1-2″ per week.
- Apply a balanced fertilizer after initial spring bloom.
- Prune spent flower stalks promptly down to the foliage.
- Remove faded leaves and trim foliage by half in late summer.
- Protect plants from early frosts that damage tender growth.
- Allow the soil to dry slightly between waterings after rebloom begins.
- In zone 5-6, mulch rhizomes well for winter protection.
Rebloom is strongest in warm climates, but you can enjoy a smaller second crop of flowers in cooler zones by providing ideal care.
Best Uses for Summer Blooming Iris
Here are creative ways to showcase iris blooming all season:
- Underplant roses, peonies or hydrangeas with reblooming iris.
- Edge a pathway or garden border with Siberian iris for months of color.
- Plant different iris varieties together for a continuous bloom progression.
- Cut iris stems freely for summer vase and table arrangements.
- Highlight patios, decks and entryways with iris planted in containers.
- Mass Louisiana iris in low boggy spots or at pond margins.
- Use tall iris as colorful see-through screens or living fences.
- Mix summer bulbs like agapanthus with Dutch iris.
Summer Blooming Iris Care Tips
Follow proper care practices for non-stop flowers:
- Water thoroughly when iris foliage seems dry or droopy.
- Apply balanced fertilizer a second time 6-8 weeks after spring bloom.
- Remove any rotted rhizomes and trim away dead leaves to prevent disease spread.
- Monitor for common pests like iris borers and thrips; treat promptly.
- Stake floppy bloom stalks of heavy flowering cultivars like Siberian iris.
- Prune any foliage damaged by hail or heavy rain to keep plants looking tidy.
- Mist plants weekly in hot dry weather to deter spider mites.
- Weed regularly to eliminate competition for water and nutrients.
Let foliage remain until it fades naturally to build reserves for future bloom.
Enjoy Long Lasting Iris Elegance
Extend your enjoyment of gorgeous iris blooms by incorporating summer flowering varieties in your landscape. With a thoughtful selection of reblooming and repeat blooming types, you can have perfectly timed color progression. Give iris ideal sun, soil, and care to realize their full potential for providing floral beauty from early summer into fall.
Iris siberica ‘Butter and Sugar’ (Siberian iris)
Hardy from Zones 3 to 8, this Siberian iris grows about 2¼ feet tall. Flowers appear from late spring to early summer sporting white standards and brilliant yellow falls. The plants thin, arching leaves add an ornamental grass–like texture to mixed borders. Butter and Sugar thrives in full sun to partial shade and medium-to-wet soil.
This variety of bearded iris blooms again and again and is hardy in Zones 3 to 10. It can grow up to three feet tall. Its heavily ruffled standards and falls are brilliant white with a very slight tinge of violet. The falls have greenish-white centers, and the beards are pale lavender. St. Petersburg makes a bright accent in beds and borders of contrasting colors. Its best grown in full sun and fairly organic, well-draining, medium-moist soil.
Probably the best source of information on irises is the American Iris Society (AIS). For membership information, call 636-274-6149. The AISs website (www.irises.org) provides links to local and regional iris societies in the U.S., as well as specialty organizations, such as the Reblooming Iris Society (www.rebloomingiris.com; 903-463-4084). These societies can recommend local growers, but if you are unable to get your irises locally, following are a few mail-order sources.
The Missouri Botanical Garden’s editor and manager of publications is Barbara Perry Lawton. She is also the president of the Garden Writers Association of America and writes a weekly garden column for the St. Louis Post-Dispatch. Louis Post-Dispatch. Her latest book is Hibiscus: Hardy and Tropical Plants for the Garden (Timber Press, 2004).
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Iris fulva ‘Lois Yellow’ (copper iris)
This is a type of the native copper iris that grows in the south. Lois Yellow can handle Zones 5 through 9 and is two to three feet tall. It offers bright green, swordlike foliage and boasts showy yellow flowers from May to June. It grows best in full sun, but it can handle some shade, especially in the southern part of its range. The soil should be fertile, slightly acidic, and consistently moist to wet. It is another good choice for water gardens.
Growing over two feet tall, this Xiphium iris blooms from late spring to early summer. The graceful single flowers are a rich golden yellow. Hardy from Zones 5 to 8, Golden Harvest needs full sun and well-draining soil. If yellows not your color, choose a different cultivar. Modern Xiphium cultivars come in white, blue, and purple but otherwise look the same. Excellent in borders and containers, they also make great cut flowers.
The border bearded reblooming iris is hardy in Zones 3–10 and grows to be 1½ to 2 feet tall. It is in the group of irises called Medians. It blooms from May to June, producing intensely white standards overlaid with yellow, and yellow-edged white falls. Grow the plant in full sun and well-draining, medium-moist, humus-rich soil.
This tall bearded remontant iris is hardy from Zones 3 to 10 and typically grows three feet tall. The showy flowers have golden-tan standards and falls. The falls have cinnamon spots on them, and the beards have white edges around them. It grows best in full sun and organic, medium-wet, well-drained soil. It looks good in sunny beds and borders.
7 Reasons Why Your IRIS is NOT Blooming |#gardening
FAQ
What iris has the longest bloom?
What is the most reliable reblooming iris?
How do you get reblooming iris to rebloom?
Do reblooming irises multiply?
Do irises bloom in shade?
Many irises will grow in total shade, but they most likely won’t flower. The majority of irises will bloom in spring or summer. Dwarf varieties tend to bloom earlier in spring, with intermediate sizes blooming later spring, and taller bearded varieties blooming late spring and summer.
When do bearded irises rebloom?
While most irises flower in the spring, there are reblooming varieties of bearded iris, like ‘Immortality’, that can flower again in the early fall. To add splashes of color to my garden during the summer, I opt for a palette of purple, blue, yellow, white, and pink.
When do iris flowers bloom?
He is always eager to learn more about different types and how to care for them. He has a knack for finding rare and beautiful varieties and is always on the lookout for something new. Iris flowers typically bloom in the late spring to early summer, around May to June, depending on the specific variety and climate.
When do irises rebloom?
While most iris cultivars will only bloom once a year for about two weeks in late spring, some varieties will flower again later in the season. And others that will bud out two or three times more if they are properly cared for. If you can’t wait til next season for your irises to bloom again, why not plant a reblooming variety?