What is Japanese Iris?
Japanese Iris (Iris ensata) is a vigorous clump forming, perennial that grows from a rhizome. It is part of the Iridaceae family and is native to Japan. Although not a true water plant, the Japanese Iris are moisture loving irises. They flourish in and around ponds during the growing months of Spring and Summer. They also grow well in the garden as long as they have enough water supplied to them. In Winter when the rhizome goes dormant they need dry conditions or the rhizome will rot. A lot of growers will plant Japanese Irises in pots and each Winter remove the pot from the pond. When shoots begin to sprout in early Spring they return the pot back to its spot. Foliage appears first in Spring which is erect and sword in shape. They will form a large clumping habit as they grow and multiply. Flower spikes will appear late in Spring. Japanese Iris are available in different colours including blue, white, pink and purple with varying patterns. Each rhizome will produce several flower spikes. Find a full sun position with at least 6 to 10 hours of sun a day to maximizes blooming potential. Japanese Iris like a slightly acidic soil and should be planted where there is protection from strong winds.
Benefits of Growing Japanese Iris
Japanese Iris are an excellent plant for when you need something for a wet or boggy area of the garden where most plants wont grow. They are excellent in and around ponds and water areas. They also make great garden bed plants too but they need that little bit of extra care to make sure they have enough water. Japanese Iris are an excellent choice for a border plant and they go very well in larger pots and planters. The large flowers are one of the reasons they are used in landscaped gardens.
How to Grow Japanese Iris
Cool to Tropical.
Height: 60cm-1.5m, Width: 20-50cm
When To Plant Japanese Iris
Plant in Winter or early Spring.
Japanese Iris need a slightly acidic, moist rich soil. Do not feed them lime or blood and bone fertilisers as this will raise the pH of the soil. If your soil is high in pH (alkaline) then you can use things like compost, leaf litter and mulch to help bring it down.
How To Plant Japanese Iris
Plant in full sun to part shade, 20-30cm apart with the plant crown just below the soil level.
Japanese Iris Plant Care
Japanese Irises need constant moisture whilst growing. Alternatively they can be grown in a boggy spot or in a pot submerged in water. However, when dormant the soil should be well draining so the rhizome can dry out during this time. Do not water. If in a pot submerged in water take it out and placed in a dry spot until early Spring where the rhizome will begin shooting. Then return it to the pond. The rhizome of the plant is prone to rotting during Winter when constantly wet.
Annually put down a layer of mulch to help keep moisture in and suppress weeds.
They are heavy feeders so applied a slow release fertilizer such as an azalea mix or Osmocote as the rhizome starts to shoot.
Trim off dead flowers stems once the blooms have faded can usually encourage a second flush of flowers. During Winter they become dormant so it this is the ideal time to clean up and remove dead foliage. They can be cut right back to near the ground.
These plants can easily be divided after a few years. Simply dig up and divide clumps during Winter then replant as soon as possible. During this time you should also renew the potting mix that they are in (if planted in pots).
Recommended Japanese Iris Varieties
With large flowers, striking patters and a water lover, Japanese Iris are a great addition to your garden.