Japanese iris care infographicThe Japanese Iris (Iris ensata), native to the wetlands of East Asia, is a beautiful plant to spice up your garden or poolside. It produces flowers of different colors according to the variety, is easy to care for, and has a lot of uses in your poolside.

What Is Japanese Iris?

The Japanese Iris is a collection of different Iris species. “Japanese Iris” can refer to Iris ensata, Iris sanguinea, and Iris laevigata. While all three species are common in Japanese gardens, Iris ensata became more popular in places outside Japan. We will be referring to Iris ensata as Japanese Iris in this article.

Iris ensata is native to Japan and other East-Asian regions. It can also be called purple Japanese Iris or yellow Japanese Iris. It is a temperate plant that grows in wetlands and around ponds. This grass-like plant is popular for its beautiful features and uses.

– Identifying

Iris ensata is very easy to recognize especially through its flowers. Here are some features of the Asian Iris:

  • Plant appearance: Iris ensata plants look like densely-packed grass. Each clump can grow 48 inches tall and spread 20 inches wide. Iris ensata plants have an underground stem called a rhizome which can also be referred to as Japanese Iris bulbs. The rhizome spreads and produces more offshoots.
  • Leaves: The green leaves of Iris ensata are sword-like. They grow in clumps and are like grasses densely packed together.
  • Flowers: Without their flowers, Iris ensata plants look like grass. Japanese Iris flowers are blueish-purple, lavender, pink, or white. Japanese Iris bloom in June and July.

If you see a plant with these features growing around a water body or loose soil, it is Iris ensata.

– Uses

Japanese Iris are not just beautiful; they have a lot of uses. Some of their uses include:

  • Swimming pool plant: If you have a swimming pool or you live close to a pond or lake, you can grow Japanese Iris to beautify the environment. These plants grow well in the soil close to a body of water and also attract beautiful harmless insects to the area.
  • Prevention of erosion: Fast-flowing water can cause erosion, so people use bricks or plants to prevent it. If erosion occurs in your surroundings, plant a lot of Japanese Iris and the problem is solved!
  • Ornamental plant: This oriental Iris is called “Botanical Butterfly” because it attracts a lot of colorful pollinators. The plant is not just pretty, it attracts pretty and safe organisms to your garden.

Now you have a lot of reasons to grow Japanese Iris. How do you grow and care for the plant? Continue reading.

How To Grow

Japanese Iris planting is an easy activity. This plant is a low-maintenance plant, so you don’t need to actively care for it.

Japanese Iris or yellow Japanese Iris

When planting your Japanese Iris, spread them at least 12-18 inches apart. This will help their rhizomes to spread properly and not compete with others.

– Planting

You should start your first Japanese Iris plants by planting their rhizomes. Growing Iris with their rhizomes is the easiest way to plant them. Soak the root and rhizome for six hours at least before planting. Remember that your Iris need appropriate spacing (12-18 inches apart).

Japanese Iris Care

Caring for and growing Japanese Iris is very easy. You just need to consider the type of soil or potting mix you use, water, temperature, light, humidity, and fertilizer given to the plant.

– Soil

Iris ensata loves very loose soil. Japanese Iris is an acid-loving plant, so the soil should be slightly acidic (pH 6 – 6.5). Your plants will grow better when you plant them near a swimming pool, pond, or a body of water. If you do not have a swimming pool or pond, you can still grow Japanese Iris. Just make sure that the soil is not compacted.

– Light and Humidity Requirements

Japanese Iris love full sun but can tolerate partial shade. Your plants will grow faster and healthier if you plant them in a place where they can get six or more hours of sunlight daily. The minimum amount of daily sunlight that Iris ensata can tolerate is four hours.

Japanese Iris love a humid environment, so you should grow them in average humidity. You can mist water around the plants to increase the humidity.

– Temperature

As a temperate plant, the Japanese Iris is cold-loving. It grows best in USDA hardiness zone 4 – 9. This means that it can survive a wide range of temperatures (from -30 F or -34 C to 25 F or -4 C). In winter, you do not have to take your plants indoors as they are winter-hardy.

– Water Requirements

As a water-loving plant, you need to water your Japanese Iris regularly. If you are growing Japanese Iris close to a pool or pond, you do not need to water them always as the nearby water will supply your plants with their water needs.

water your Japanese Iris regularly

For plants grown in other places (far from pools) or containers, you should water them daily in spring and summer. Remember that Japanese Iris need friable or loose soil, so you have to make sure that the soil is not waterlogged.

You should also pay attention to the pH. Iris ensata grows best in slightly acidic soil. If the water source near your plants is basic, you should add two or three teaspoons of vinegar to a gallon of water to water your plants.

– Nutrient 

Iris ensata is a heavy feeder. One reason you have to fertilize your plant regularly is that the soil is loose, so nutrients are easily washed off. You should fertilize your plants regularly.

To help reduce the cost of fertilizer, you should grow your Japanese Iris in amended soil. Use a balanced fertilizer in the growing season. Make sure to fertilize your plants when they are blooming.

– Grooming

The clumpy nature of Japanese Iris can attract pests or even affect the soil composition. You should remove dead leaves from the ground. Also, look for and remove pale and weak leaves. Transplanting Japanese Iris can be a necessity especially when some clumps look too crowded. 



There are different methods to propagate Iris Ensata. Listed below are propagation methods of Japanese Iris that you can try:

– Rhizomes

As you already know, Japanese Iris have underground stems called rhizomes. These rhizomes can grow into new plants, so propagating Japanese Iris by splitting their rhizomes is the easiest and most common method of propagation.

Aside from the purpose of propagation, you need to split the rhizomes every three or four years especially when the Iris are growing out of control in their location. To propagate the plant with the rhizome, dig out any section of the plant (you do not need to dig out the entire plant).

When you have revealed a section of your Japanese Iris, use a shovel or any handy tool to cut out that section. Cover the remaining parts of the plant and soak your split rhizome in water at least for 12 hours before planting.

Make sure that you plant the rhizome in suitable soil else it may start to decay from the ground.

– Seeds

Iris ensata plants are also easy to grow with seeds. The seeds of these plants have a high germination rate and germinate quickly. After successful pollination, your Japanese Iris plants will produce seeds. Wait until the seeds are matured enough and are about to fall off the plant before you collect them.

You can wait a few weeks before planting the seeds, or you can plant them immediately. However, it is best to wait until the next growing season before planting the seeds. You should start the seeds in a container so that you can nurture them until they are matured enough to grow in soil.

Water the seeds regularly and make sure that their growing medium is well-drained.

– Seedlings or Offshoots

Your Japanese Iris plant rhizomes produce a lot of offshoots. You can collect these offshoots and plant them somewhere else. To collect an offshoot, dig off that section to reveal the rhizome. Use a shovel to cut off the rhizome attached to the offshoot.

methods to propagate Iris Ensata

Cover the remaining part of the plant and take that offshoot somewhere else. You can plant it immediately, but you can soak it in water for six to twelve hours before planting.

Which method of propagation will you use for your Japanese Iris?

Potential Problems

Japanese Iris are easy to grow when they are in the right media and receive just enough water and nutrients. They may, however, get sick or you may face one or two problems when growing the plants. Here are some examples of problems you can face when growing Japanese Iris:

– Weak Plant

A plant that is weak or dying is a sign that the soil is poor. Japanese water Iris is very sensitive to the type of soil it grows in, so will appear weak when grown in poor soil. Japanese Iris plants need loose soil. The soil should not be compacted and you should water it regularly.

While Japanese Iris love wet soil, they do not like compacted soil. Make sure that the water drains quickly (i.e. does not stay on top of the soil) so that your plants can remain healthy.

– Pests

Pests such as snails, slugs, and insects can attack your Iris and if care is not taken can kill the plant. You should spray pesticides on the Japanese Iris to repel or kill the pests. Also, planting your Iris ensata close to pest-repellant plants such as mint can help prevent pests from reaching the plant.

– Death of Other Plants

If other plants in your garden are dying while your Japanese Iris are not, it could mean that the root and rhizome of your Japanese Iris plants are competing with the other plants for space and nutrients.

Remember to divide your Japanese Iris regularly. Also, remember to space your Japanese Iris plants 12-18 inches apart when planting.


Does Japanese Iris like to be rootbound?

Japanese Iris prefers slightly crowded roots, as it enhances blooming. Adequate spacing should be maintained to avoid excessive overcrowding.

What is an interesting feature of the Japanese Iris?

Japanese Iris exhibits captivating variegated foliage, adding an alluring visual appeal to its already stunning flowers.

Does Japanese Iris do well outdoors in the summer?

Japanese Iris thrives outdoors during the summer, benefiting from ample sunlight, provided adequate moisture and soil conditions are maintained.


Even though Japanese Iris are unique plants because of their soil and water needs, they are still very easy to grow. Here are some useful tips to grow Iris ensata that you should remember:

  • Japanese Iris grow best in USDA hardiness zones 4 – 9. This means that they tolerate a wide temperature from -30 F (-34 C) to 25 F (-4 C).
  • Iris ensata is native to wetlands, so they are compatible as side-pool plants. Plant them beside your pools and ponds.
  • The soil or potting mix best for Japanese Iris should be loose. It must drain water quickly.
  • Japanese Iris are heavy feeders. Feed them with a balanced fertilizer in the growing season and also when they bloom.
  • Pay close attention to the soil pH. Japanese Iris grow best in pH 6 – 6.5

Are you ready to grow some Japanese Iris? This guide will surely come in handy for you.

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