This seems to have been a special fall for bearded irises in Northeastern North America. Several readers have written over the last few days (early October) to tell me that their irises are blooming for a second time. And these are irises that normally only bloom in late spring/early summer. My correspondants seemed especially concerned as to whether this off-season bloom would harm the plant.
Well, let’s answer that right off the bat: probably not. Plus it’s not as rare a phenomenon as you might think.
Plenty of Plants Rebloom Occasionally
There are quite a number of spring-flowering plants that occasionally rebloom in fall, including oriental poppies, primroses, perennial geraniums, lilacs, rhododendrons, azaleas, magnolias and iris. Usually this happens when the plant has undergone some kind of stress, such as a long period of drought or an exceptionally hot summer. However, sometimes there is no clear explanation. The plant simply starts to bloom outside of its normal season and no one knows why. And this out-of-season flowering is not really detrimental to the plant: it usually resumes its normal cycle the following year.
(Sometimes it’s best not to ask questions, but just to enjoy the result!)
Blooms in the fall usually do mean lighter bloom the following spring. That’s because the branches, stems or rhizomes that bloomed off-season won’t have time, at least in cold climates, to produce new flower buds for the upcoming spring. On the other hand, fall flowering is generally rather sparse and therefore it doesn’t necessarily have that much of a negative impact on the spring bloom to come.
So much for regular bearded irises blooming in the fall, but there are also iris cultivars that naturally rebloom, that is to say, irises that bloom as usual in the spring, then a second time at the end of the season (August, September or October, depending on the local climate). They’re even offered in plant catalogs under the name reblooming irises.
In order to flower a second time, however, reblooming iris need the very best in growing conditions: full sun, good drainage, rich soil, regular fertilization (they prefer fertilizer not overly rich in nitrogen), little competition, etc. And they must be well established: rarely will they bloom a second time the first year.
Also, although these irises are generally just as hardy as the other bearded irises, that is, to zone 3, they only tend to rebloom in regions with long summers. So it’s unlikely they’ll rebloom in zones 3 and 4, where summers are short, and rebloom is rare even in zone 5. It’s in zone 6 and warmer that this trait is the most reliable. But even in Zone 7, and despite the best care in the world, reblooming irises don’t reflower every year.
Reblooming is also unreliable in areas that with hot, humid summers, such as the US Gulf Coast, in spite of its mild climate. Hot, humid weather seems to stress reblooming irises … and not in the right way. In California, on the other hand, where the climate is both mild and on the arid side, some reblooming irises will bloom a third or even fourth time! They can even flower on and off throughout the year!
In My Own Garden
I’ve planted several reblooming irises over the years, but none have ever rebloomed. I do realize I live in USDA Zone 3 (AgCan zone 4), where experts claim the chances of reblooming are slim, but I’m an eternal optimist. Each fall I therefore eagerly scour my gardens for any sign of off-season bloom and probably will until my dying day. I figure I might as well grow reblooming irises as one-offs, as I still get abundant spring bloom and have a slight chance of flowers in the fall. After all, nothing lost, nothing gained!
Some Varieties to Try
Here are some reblooming iris that are available, at least from perennial growers … but you’ll find many more if you dig through specialist iris catalogs.
- I. x germanica ‘Again and Again’
- I. x germanica ‘Autumn Circus’
- I. x germanica ‘Autumn Echo’
- I. x germanica ‘Best Bet’
- I. x germanica ‘Café Blue’
- I. x germanica ‘Champagne Elegance’
- I. x germanica ‘Cordoba’
- I. x germanica ‘Double Click’
- I. x germanica ‘Double Your Fun’
- I. x germanica ‘Earl of Essex’
- I. x germanica ‘Eternal Bliss’
- I. x germanica ‘Feed Back’
- I. x germanica ‘Forever Blue’
- I. x germanica ‘Hemstitched’
- I. x germanica ‘Immortality’
- I. x germanica ‘Jennifer Rebecca’
- I. x germanica ‘Mariposa Skies’
- I. x germanica ‘Misty Twilight’
- I. x germanica ‘Pink Attraction’
- I. x germanica ‘Presby’s Crown Jewel’
- I. x germanica ‘Pure as Gold’
- I. x germanica ‘Recurring Delight’
- I. x germanica ‘Speeding Again’
- I. x germanica ‘Stellar Lights’
- I. x germanica ‘Summer Olympics’
- I. x germanica ‘Thrice Blessed’
- I. x germanica ‘Witch of Endor’
- I. x germanica ‘Ziggy’
Other Reblooming Iris
There are also reblooming irises in other categories, notably Siberian irises (I. sibirica) like ‘Ever Again’ and ‘Slightly Envious’, and Japanese irises (I. ensata) like ‘Purple Plus’ and ‘Triple Treat’, although they tend to bloom immediately after the first bloom or shortly thereafter, not in late summer or autumn.
Are you interested in reblooming irises? If so, you might want to join the Reblooming Iris Society.
Catalogs Offering Reblooming Irises
Here’s just a sample of many catalogs offering reblooming irises.