Once you see a garden full of bearded iris flowers and they start to bloom, something magical happens.
You can see this as early as March’s start in some regions, and it can carry on until almost the end of June. With so many types of iris, you can find some rebloom late summer and fall.
The hardy perennials of iris plants can thrive in USDA Zones 3-9, which offer winter temperatures below freezing, enabling the plant to enter the dormant before the following year’s outburst.
Iris can be a great plant for any gardener, and they hold a place in the heart of the American Iris Society and made famous by Van Gogh.
You have a diverse set of plants, and it is the bearded iris as one of the three categories of which the most common is the iris germanica.
In this guide, you can learn more about when do iris bloom and how often can times reblooming irises bloom in the year. (Find out Which Flowers That Rabbits Won’t Eat)
How Many Times a Year Do Irises Bloom?
You can find one or two varieties of Iris that bloom a couple of times per year. However, if you see gardens blooming throughout the year, they often have several varieties that extend iris bloom time for different periods.
You will discover irises suit most soil types, from well-drained for bearded irises to water-logged, where you find Japanese irises.
Others, such as the Siberian irises, flourish in moist soil. Miniature bulbous irises (Iris reticulata and I. danfordiae) need good drainage, so they’re more suited to rock gardens or similar.
Sun requirements are that most irises like full sun or even light shade. Temperatures are not overly critical as they can adapt.
Irises being remontants all rebloom in USDA Zones 5 to 6, and usually, during late summer or fall, it does depend on how hot the weather conditions in the summer get.
Remontant cultivars need more water and a little extra feeding of fertilizer after first bloom since they are more productive than other varieties.
Deadheading spent flowers can help your repeat bloom. If you have good workable soil, you can plant in pots at any time, in your garden, plant midsummer to early autumn.
Here’s a look at some easy to grow varieties reblooming iris.
Iris ‘Autumn Tryst
A remontant tall bearded iris, which grows 2½ to 3 feet tall. It has fragrant white flowers and rosy lavender edges. Hardy from hardiness zones 3 to 10 with first blooms in May, it’s ideal for mixed perennial beds.
Iris ‘Baby Blessed’
Being a standard bearded dwarf (SDB), it is hardy from Zones 3 to 10. It has yellow flowers on 8- to 15-inch flower stalks and will flower first in the spring and possibly multiple times through the season.
They can cope with more shade and a broader range of environmental conditions to extend your bloom season than other bearded irises. (Read Facts About Sunflowers)
Iris Fulva ‘Lois Yellow’ (Copper iris)
A cultivar of the copper iris is ‘Lois Yellow.’ It thrives in hardiness zones 5 to 9 and grows two or three feet tall. It displays bright green foliage, sword-like leaves and yellow flowers from May to June.
It is best grown in full sun and tolerates some shade. Soil needs to be fertile, slightly acidic, and always moist to wet.
Iris ‘Golden Harvest’
The Xiphium iris grows over two feet tall and blooms late spring to early summer. It has single flowers that are rich golden yellow.
It grows best in Zones 5 to 8, where the ‘Golden Harvest’ needs full sun and well-draining soil. They also make great cut flowers, and different cultivars offer other colors.
Iris ‘September Replay’
Being tall bearded irises that are hardy in Zones 3 to 10 and grow three feet tall. It is a good plant for sunny beds and borders, growing in full sun with organic, medium-wet, well-draining soil.
Iris siberica ‘Butter and Sugar’ (Siberian iris)
The Siberian iris grows 2 ¼ feet tall in zones 3 to 8. Flowers show in late spring to early summer where ‘Butter and Sugar’ thrive in full sun to partial shade and medium-to-wet soil. It has a grass-like texture on iris leaves.
What month do irises flower?
There have been hundreds of bearded rebloomers from all categories to be registered with the American Iris Society in the last few years. Many are all-season bloomers, while some bloom in spring and once again in summer or fall.
For gardeners interested in late-blooming irises, many bearded varieties bloom from early spring to early summer.
Some Siberian irises (Iris sibirica) and Japanese irises (I. ensata) selections bloom mid-spring to early summer, and beardless southern blue flags bloom into early summer.
Why Are My Irises Not Blooming?
Most iris varieties have a wide hardiness range from the United States Department of Agriculture zone 4 to 9. There are many reasons irises not blooming. Most species come from rhizomes, although some stem from bulbs.
Both are underground storage cells containing reserves of carbs and embryonic plants.
Should the conditions such as temperature and lighting be right, they sprout stems and leaves to produce flowers eventually.
Should the rhizomes or bulb be poor, then there won’t be flowers. You can often find rotten or mushy and under-formed rhizomes, which lead to stunted plants with no blooms.
Some species need well-drained soil and full sun; if the wrong type is grown, they can fail to bloom as you expect.
Depth of planting is another area, and is the iris rhizomes are too deep; this can stop them from growing. Rhizomes should be close to the surface and the tops just below. Irises are drought-tolerant, yet if there is no water, you’ll find they refuse to bloom. (Learn How to Keep Squirrels Out of Flower Pots)
Check for iris borer and remove any eggs you may see over the winter.
How Do I Get My Iris to Bloom Again?
Growing conditions need to be right, and it begins with your rhizome being close to the soil surface. Here are other areas to go through to make sure you offer the best chance for your iris to bloom again.
- It would help if you plan your iris garden once you know the species you’ll grow. If planting bearded iris, remember they the right sun conditions with 6 to 8 hours of daily direct sun. Soil needs to be loamy, well-draining soil composed of sand, silt and clay.
- The bearded iris species are common, and if purchasing, you’ll get the rhizome in a plastic bag, make sure it doesn’t dry out.
- Late summer thru early fall, when nighttime temperatures are around 40 to 50 degrees Fahrenheit, are the best times to plant to achieve flowering come the following spring and summer.
- Aerate the soil with your tiller to 12-15 inches deep. Add a compost layer about 2 to 4 inches in depth. Make a mound for your rhizome by digging a shallow hole. This should be 10 inches in and have a ridge in the center.
- Place your rhizome horizontally and spread its roots down the sides.
- Cover the roots and rhizome bottom with soil.
- If you have the Dutch iris, plant the bulb with a pointed side up around 5 inches under the soil line. Fall and spring are suitable for planting. Dutch iris is best when grouped in tens in a square foot area.
- Once rhizomes or bulbs are buried, water the area immediately. Don’t mulch as it will stop the sun from feeding the plant. Also, to avoid rhizome rot, watering only when needed and also use an all-purpose fertilizer lightly. You may need to use a stake for support.
Deadhead your iris frequently, as this is key to encouraging new flowering from buds that grow further down the stem. Once flowering is over, cut your tall bearded iris stalk to soil level but above your rhizome or bulb.