Japanese Irises (Iris ensata) are easy-to-grow flowering perennials with beautiful orchid-like flowers. As long as you grow your Japanese Irises in a sunny location and plant it in moist, acidic soil- they will grow vigorously year after year.
Once your irises are established, you will be rewarded with gorgeous flowers even if you don’t do anything- perfect for the lazy gardener. Japanese Irises need abundant moisture so if you have a stream or pond in your garden, plant your Japanese irises along the edge of the water. Here is a beginner’s guide on how to care for your Japanese Irises.
How to Grow Irises Video
Japanese Irises Planting Basics
| Name | Japanese Irises |
| Botanical Name | Iris ensata |
| Flower Color | Many Colors- Purple, Yellow, Blue, White |
| Height | 24-48 inches |
| Sun | Full Sun |
| Soil | Moist, Acidic Soil |
| Bloom Time | Mid-Summer |
| Zones | 4-9 |
| Plant Depth | Plant 2 inches deep |
| Plant Spacing | 12 to 24 inches apart |
| Toxic to Cats and Dogs | Toxic |
Japanese Irises (Iris ensata): Size
Japanese Irises grows to 24-48 inches tall.
Planting Your Japanese Irises
Where to Plant Japanese Irises (Iris ensata)
Japanese irises are best planted in sunny locations receiving at least 6-8 hours of sunlight per day. They prefer moist, well-drained, acidic soil. Plant your Japanese iris alongside a pond or stream, it will thrive in soil that is moist.
| Sun | Full Sun |
| Soil | Moist, Acidic Soil |
How to Plant Japanese Irises
To plant your Japanese irises, dig a hole around 2 inches deep. Center the rhizome and cover it with soil. Water thoroughly. Keep up with the watering until roots are established. Japanese irises need constant moisture so you should make sure you are watering them. Use a bulb planter tool to make planting your bulbs easier.
When is the Best Time to Plant Japanese Irises?
The best time to plant your Japanese iris is in the Fall. Make sure you plant your Japanese iris 4 weeks before the first frost to ensure there is enough new root growth before winter.
How Deep Should You Plant Japanese Irises?
Plant your Japanese Irises 2 inches deep.
Dividing Japanese Irises
How Often do you need to Divide Japanese Irises?
Japanese irises need to be divided every 3 years. It will start to get overcrowded and will benefit from division.
How to Divide Japanese Irises
Water the Japanese iris you will be dividing (or divide after rain). It’s easier to divide your Japanese iris if the soil is moist. With a shovel, divide your Japanese irises by digging up the entire Iris exposing the roots and rhizomes. Use scissors and a shovel to cut up the iris clump into several divisions. Plant each division in a sunny location with well-drained soil. Water thoroughly. Keep up with the watering until the roots are established.
Check out my article and video for a step-by-step guide on How to Divide Irises
Propagating Your Japanese Irises
How to Propagate Japanese Irises (Iris ensata)
The best way to propagate Japanese irises is by division. Water the iris you will be dividing (or divide after rain). With a shovel, divide irises by digging up the entire Japanese Iris exposing the roots and rhizomes. Use scissors and a shovel to cut up the Japanese iris clump into several divisions. Plant each division in a sunny location with well-drained soil. Water thoroughly. Keep up with the watering until the roots are established.
Care for Your Japanese Irises
Do You Need to Water Your Japanese Irises every day?
Japanese irises need abundant moisture to thrive. You should keep up watering and make sure the soil does not dry out.
Do You Need to Deadhead Japanese Irises After They Bloom?
Japanese irises don’t need deadheading after bloom. The only time you’d want to deadhead Japanese irises is if you have a rebloomer (although most rebloomers are Bearded irises). Another reason to deadhead Japanese irises is if you want to tidy up your irises by removing the dead flowers. Know that there is no guarantee that Japanese irises that are sold as rebloomers will rebloom after deadheading.
What to Do with Your Japanese Irises After They Bloom?
Japanese irises don’t need deadheading. Just leave your Japanese irises alone after they bloom. Keep the leaves of your Japanese iris intact since it’s vital for the leaves to continue photosynthesizing even after they bloom so it will continue to feed the iris rhizome.
How Often Should You Fertilize Your Japanese Irises?
Fertilize your Japanese irises once before bloom and once in the Spring when the foliage are a few inches tall.
What Fertilizer Should You Use on Your Japanese Irises?
Use a balanced fertilizer on your Japanese irises.
Troubleshooting Your Japanese Irises
Are Japanese Irises Deer Resistant?
Japanese irises are deer-resistant plants. Squirrels and rabbits will also not bother your Japanese irises.
Are Japanese Irises Toxic to Dogs and Cats?
Japanese Irises are toxic to dogs and cats. According to the ASPCA, Irises contain Pentacylic terpenoids (zeorin, missourin and missouriensin) which are toxic to dogs and cats. It can cause vomiting and diarrhea. Iris rhizomes contain the highest level of Pentacylic terpenoids.
What are the common problems of your Japanese Irises?
Japanese Irises are typically pests and disease free. Bearded irises are commonly afflicted by iris borers.
Preparing Your Japanese Irises for Winter
How Should You Prepare Your Japanese Irises for Winter?
To prepare Japanese irises for winter, cut back Japanese irises in the Fall by removing the stems and leaves. Cut your Japanese irises down so that only around 2 inches of foliage are left. Wait until after 3-4 frosts when the Japanese iris leaves have completely died off before cutting back Japanese irises. It’s important that you leave the leaves of your Japanese irises intact for a few weeks after the bloom dies so it can deliver much needed energy to the rhizomes for next year.
Check out my article and video for the step-by-step guide on how to cut back irises
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Beginner’s Guide: How to Divide Irises (video)