How to Grow and Care for Japanese Iris

This perennial performs best in full sun unless you are growing it in an area that experiences very hot summers. In the latter case, it profits from a bit of afternoon shade.

Growing Japanese Iris Plants – Information And Care Of Japanese Iris

When you are looking for an easy-care flower that loves wet conditions, then the Japanese iris (Iris ensata) is just what the doctor ordered. This flowering perennial is available in a range of colors, including purples, blues, and whites, with attractive medium green foliage. Care of Japanese iris is moderately simple when the plant is located properly. Learning when to plant Japanese irises is also an important part of their performance.

Growing Japanese Iris Plants

The timetable for when to plant Japanese irises may involve amending the soil with acidic, organic amendments prior to planting the rhizomes in early fall.

Unlike many garden flowers, Japanese iris care does not involve planting in a well-draining soil. In fact, growing Japanese iris plants flourish in boggy areas, near ponds and water features or even potted and placed in these bodies of water. Water should be acidic. If you’re unsure of the pH of your water, add 2 to 3 teaspoons (10-15 ml.) of vinegar to a gallon of water to obtain the level needed for successful care of Japanese iris.

If a pond or water feature is not available, growing Japanese iris plants is best done in an area that remains damp and moist for best performance and easiest care of Japanese iris.

Care of Japanese Iris

Once planted and placed in the pond, Japanese iris care is minimal. Limit fertilization to plants with a well-developed root system, and only use plant food that is high in nitrogen.

Japanese iris care will include the division of the rhizomes every three to four years. Crowded plants tend to offer fewer blooms. Division keeps growing Japanese iris plants in optimum condition to provide the best possible bloom in summer. After division, consider placing a few rhizomes in pots to live in your water feature or pond. Pot in a heavy soil, such as red clay mixed with sand.

Growing Japanese iris plants are rarely bothered by disease or the borer which often attacks the traditional bearded iris.

You can enjoy growing Japanese iris plants with delicate blooms in moist and shady locations if you provide plenty of acidic water. This simplifies their care and lets you just enjoy the flowers.

How to Grow and Care for Japanese Iris

David Beaulieu is a landscaping expert and plant photographer, with 20 years of experience.

The Japanese iris is related both to irises commonly grown in the landscape, such as the bearded iris (Iris germanica), and to such wild iris plants as the Northern blue flag (Iris versicolor), a native of North America. Japanese irises come in several colors. and the flowers are flattish measuring about 3 to 6 inches across, rising above green blade-like foliage. The bulbs should be planted in the fall for a strong spring display. Because these irises like to grow around water during the spring and summer months, they are useful in certain damp and boggy problem areas of the landscape where other plants would fail miserably. The iris family, including the Japanese iris, is toxic to humans and animals

Light

This perennial performs best in full sun unless you are growing it in an area that experiences very hot summers. In the latter case, it profits from a bit of afternoon shade.

Soil

Japanese iris wants friable, loamy soil. When soil particles become too tightly packed together, the roots of the Japanese iris cannot breathe, and the plant suffers. This is why it is critically important to provide the plant with friable soil.

Water

Japanese iris needs a lot of water in the spring, less (but still a significant amount) in the summer, and way less in the fall and winter. Make sure that the Japanese iris is supplied with proper irrigation. The amount required varies based on the time of year.

In general, water Japanese iris daily in the spring and summer. This plant requires more water than many landscape plants during the growing season. This is especially true in the spring, which is the season when the plant is growing most actively. But, even in summer, keep the soil evenly moist; never let it dry out completely during the summer. Problem is, during the rest of the year (fall and winter), the plant can suffer from being in excess water. So you have to strike a careful balance.

Temperature and Humidity

This iris is cold-hardy and it tolerates a large range of temperatures, even deep freezes. Japanese irises thrive in humid conditions. You can mist them and they will be happy.

Fertilizer

This plant is a heavy feeder. Grow it in an area that has been amended previously with organic matter and work compost into the soil around it annually.

Types of Japanese Iris

Different types of Japanese irises have varying shapes, sizes, and shades of purple and white petals. Here are popular choices:

• ‘Japanese Harmony’ features white petals and a center fluff of smaller purple petals.
• ‘Japanese Pinwheel’ offers varying shades of flared purple petals with thin white rims.
• ‘Japanese Sandman’ is a full-petaled light purple flower with a center fluff of yellow, white, and purple petals.
• ‘Freckled Geisha’ has white papery-thin petals outlined with purple ruffles and a hint of yellow fluff in the center.
• ‘Dinner Plate’ is a newer trademarked variety of Japanese irises with extra-large ruffled layers of petals of either white, purple-white, purple-pink, or purple-blue combinations.

Propagating Japanese Iris

The very best way to propagate Japanese iris is by division. These flowers spread underground by rhizomes and they will need to be divided either in the spring or fall by taking these steps:

1. Dig up a root ball and bring it up from the ground.
2. Gently break apart the root ball into two to three plants.
3. With a sanitized garden-cutting tool, trim dead roots. Note that healthy live roots will look white.
4. Keep the roots moist until you plant them back into the ground.

Potting and Repotting Japanese Iris

Because the plant is finicky about water (whether too little or too much), the easiest way to grow Japanese iris is as a potted plant for your water feature. When plants are grown in containers, they give you more flexibility because you can move them around based on their needs and your own needs. You can even place a potted Japanese iris in standing water during the spring and summer. Because the plant is intolerant of excessive water in the off-season, you can simply take the pot out of your water garden in the fall. Shallow and wide plastic pots with good drainage make ideal containers for Japanese iris plants that stand in water.

Overwintering

To keep the plants happy in harsh weather, plant your Japanese iris, pot and all, in the ground (somewhere else away from wet areas in your garden) to overwinter. And then transport the plant, pot and all, back to the water feature at the beginning of the next spring.

Common Pests

Japanese iris are vulnerable to pests such as snails and slugs. Aphids and iris borers are also attracted to this flower. Pesticides and insecticidal soap will help control these pests.

How to Get Japanese Iris to Bloom

If your Japanese iris’ pretty purple, pink, or white blooms are weak and you can’t detect the sweet fragrance they usually emit during their peak summer months, there could be a few issues. For better blooms, consider the following:

• The plants may not be getting enough sun to bloom correctly, which means they need to be replanted in a sunnier spot.
• The bulbs could have been buried too deeply in the soil which compromises the growth of rhizomes and flowering. Dig up the bulbs and replant no deeper than 3 inches for better results.
• The irises could be overcrowded which also can decrease their ability to bloom, which means digging them up and dividing them so they are planted about 8 inches apart.
• No blooms could also mean the rhizomes are mushy or rotted, which could be a result of compacted soil. Dig up, cut away affected rhizomes, and amend the soil to help restore blooms.

Common Problems With Japanese Iris

Though happy Japanese irises do not need much supervision there’s generally one problem that can affect these plants, and that’s fading colors. Usually, the Japanese iris boasts deep colors. But if it’s fading, it could mean several things:

• It may be shocked due to transplanting or extreme temperature changes.
• Possibly a critter or pest has dug the soil around the plants exposing the rhizomes.
• Another reason is age. If the iris has seen a couple of seasons, it could be ready to expire.

Because of its tolerance for wet soil in spring and summer, the Japanese iris is an ideal candidate for use around water features, ponds, and streams.

Japanese irises spread via underground rhizomes. A colony of plants will grow vigorously and soon start to grow into each other’s space, resulting in overcrowding. To solve the problem, transplant some of the plants out of their patch to another suitable spot in the yard. This will give sufficient “elbow room” to the remaining plants.

What should I do with Japanese irises after they bloom?

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1. Iris ensata. North Carolina Extension Gardener Plant Toolbox.
2. Iris. Pet Poison Helpline.