How to Grow Japanese Iris

Updated on February 3, 2020
OldRoses profile image

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.

Purple Japanese Iris
Purple Japanese Iris | Source

What are Japanese Iris?

Japanese iris (Iris ensata) may look exotic, but they are easy to grow. As their name implies, they are native to Japan where they have been grown and bred for 500 years. Japanese iris are beardless iris like their cousins, the Siberian iris, but their flower petals are larger and flatter, earning them the nickname "Butterfly Iris". The flowers range in color from purple to blue to pink to white and many bi-colors. They bloom at the end of the “iris season” after the Siberian iris, normally in mid- to late June. Their leaves are thinner and more grass-like than the bearded iris. They are also slightly shorter, about 40” tall. Japanese iris are hardy in USDA growing zones 4-9.

How to Grow Japanese Iris

Japanese iris require a minimum of 6 hours of full sun each day. In warmer climates, shade in the afternoon is preferred to keep them from drying out. They like moist, well-drained soil that is more on the acidic side. They are often planted on stream banks, their natural habitat, where the soil remains constantly moist. They are not pond plants, however. Their crowns must remain above the water line. Areas with a high water table are also good choices for planting your Japanese iris.

Japanese iris can be planted any time from spring until fall. Don’t allow your rhizomes to dry out before planting them. Soaking them overnight before planting is a good idea. Plant them so that the tops of their rhizomes are at least one inch below the soil surface. Keep your plants well mulched to make sure that the soil remains cool and moist and to keep down weeds.

Japanese iris are what is known as heavy feeders, rapidly depleting the soil of essential nutrients. It’s a good idea to fertilize them every year, either right before they bloom or just after they bloom. Use the same fertilizer that you would use on your acid loving plants such as azaleas and rhododendrons.

Bicolor Japanese Iris
Bicolor Japanese Iris | Source

How to Divide Japanese Iris

Like most perennials, it’s a good idea to divide your plants every 3 to 4 years to maintain good health. You will notice that your iris clumps expand upwards each year because new roots grow above the old roots consequently forcing the bulbs upwards towards the top of the soil where it is dryer which is not conducive to good growth for these moisture loving plants. You should divide your clumps before they reach that point.

Late spring or early summer is the best time to divide and replant your iris. Divide them by using a garden fork to carefully dig up the rhizomes about a month after they finish blooming. Use a sharp knife to cut them apart. Replant the outermost, young rhizomes which are healthy and discard the older center ones which will not grow and bloom as well. Make sure that each rhizome has both leaves and roots. Replant them with the tops at least one inch below the soil surface. If you are not going to be replanting your rhizomes immediately, keep them moist by storing them in bucket of water until you are ready to plant them. Smaller divisions can take up to two years to reach a size where they will bloom so be patient.

My favorite are the striped flowers
My favorite are the striped flowers | Source

How to Use Japanese Iris for Cut Flowers

Japanese iris make excellent cut flowers. Harvest your flowers early in the day. Choose buds that are just beginning to open rather than flowers that are fully open. The buds will open in a few hours in the vase. Place your flowers in a bucket of tepid water until you are ready to create your arrangement. When you are ready to arrange them, re-cut the stems about an inch above the original cut at an angle. To ensure the longest life for your flowers, keep your arrangement out of direct sunlight. It’s also a good idea to place it away from drafty doors and windows. Be sure to remove dead and dying flowers promptly.

Add an exotic look and prolong the iris season by planting Japanese iris. They are hardy, easy to grow plants for the moister areas of your yard.

Questions & Answers

  • Can I add vinegar when watering Japanese Iris?

    No, vinegar is a strong acid that is often used as a weedkiller. In this case, acidity refers to the pH of the soil, not acid like vinegar. Your best bet is to use a fertilizer specially formulated for acid-loving plants. I am an organic gardener, so I like to use pine needles which are acidic for my acidic soil loving plants. Pine needles are a natural, renewable source of acidity. I gather them from underneath evergreens and use them to mulch around my acidic soil loving plants.

  • If I buy a Japanese Iris from a nursery and it is potted is it okay to just place it as potted in the ground?

    Yes, you can plant it straight into the ground. Just make sure that the top of the soil that was in the pot is even with the top of the soil in your garden. If you plant too deep or too shallow, the rhizome will die.

© 2015 Caren White


    0 of 8192 characters used
    Post Comment
    • OldRoses profile imageAUTHOR

      Caren White 

      5 years ago

      Flourish, I'm knee deep in catalogs and counting the days until spring. Thanks for reading and commenting.

    • FlourishAnyway profile image


      5 years ago from USA

      You have me looking forward to Spring!

    • OldRoses profile imageAUTHOR

      Caren White 

      5 years ago

      Sorry Will, but Japanese iris require moisture. They are best grown in wet soil.

    • WillStarr profile image


      5 years ago from Phoenix, Arizona

      Can they be grown in the Arizona desert? We live in Phoenix.

    • OldRoses profile imageAUTHOR

      Caren White 

      5 years ago

      Heidi, so sorry that you can't grow iris. They are one of my favorite flowers. Thanks for reading, voting and commenting.

    • heidithorne profile image

      Heidi Thorne 

      5 years ago from Chicago Area

      Irises are lovely, but I've never been able to grow them successfully. I think it's a soil quality issue. Thanks for the info! Voted up, useful and beautiful!


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)