Japanese Irises, the Hanashobu of Japan
The huge ruffled dinner plate size flowers of the Japanese iris have
been developed over centuries in Japan. They have been developed from
one species I. ensata
. The species has fairly wide falls which hang down
and small narrow upright standards. The color is a deep red violet or
maroon. They are still sometimes referred to as I. kaempferi
the former name of the species I. ensata
. It has probably been
cultivated in Japan for over 500 years. They are referred to as
hanashobu in Japan. You may also hear the terms Edo, Higo and Ise used
to classify Japanese irises. Following is a brief description and
history of these three types of Japanese irises.
When Japanese irises were first cultivated in Japan there were many
color variations of the species found in the Asaka marshes near Tokyo
that are not known today in the wild. These were collected and
hybridized. They were raised in fields and had to withstand the rigors
of an outdoor garden. They had a wide range of colors and patterns but
were more simple in form. These became known as Edo varieties, Edo being
the old name of Tokyo.
In the Kumamoto Prefecture the Edo strains were being bred but due to
the heavy rain in this area the plants were bred to be enjoyed indoors.
There were elaborate traditions associated with the manner in which
these iris were displayed. These came to be known as Higo strain and
were bred for white and strong colors, with none of the patterns or pale
colors found in the Edo strains.
The Edo and Higo strains with their heavy substance were in stark
contrast to the very delicate Ise varieties. The Ise iris were
hybridized from species collected in Ise‑Matsuzake district on Honshu.
They were associated with religious shrines and their form was very
controlled. The flower had to have three falls that were wide,
overlapping and hung downward. The standards were erect, at a pleasing
angle, and the style crests finely toothed to give the bloom a feeling
of delicacy. Only pale colors were used, often pink shades. Like the
Higo varieties they were bred to be viewed indoors and the Ise often do
not have enough substance to stand up in outdoor gardens.
Our western hybridizers have taken both the Higo and Edo strains, and
occasionally the Ise, to develop our wide range of Japanese irises. The
flowers come in all shades of blue, red violet, purple and white. They
often have interesting patterns of dots, stripes, veining and rims in
contrasting colors. The form can be similar to the old Ise form with
three falls or can have six, nine or twelve falls. Often the styles are
expanded to form a fluff in the center of the flower. The flowers can be
tailored or ruffled, flat and flared or pendant. Often the flowers can
be eight to twelve inches in diameter. Truly spectacular!!
These spectacular irises are surprisingly easy to grow if you pay
attention to a few of their requirements. It is a common but mistaken
belief that Japanese Irises need to grow in water. In fact in cold
climates they do not like to be in water in the winter. They will do
just fine in ordinary garden conditions as long as they are given
sufficient water through the growing season, about one inch a week if
there is insufficient rain. Japanese irises prefer a position in full
sun and require an acid soil rich in organic materials. Our soils in the
Puget Sound area are usually about the right acidity, between 5.5 and
6.5 in PH. Japanese irises will not grow in alkaline soil so never add
lime. Many people like to use bone meal as a fertilizer and soil
amendment, never use it on Japanese iris as it has an alkaline reaction
and will stunt or even kill them. Japanese irises are very heavy feeders
and require a liberal application of balanced fertilizer such as a 12‑
12‑12, in spring and just before bloom time.
Early fall is the best time to plant Japanese irises so they have time
to establish new roots before cold weather. When planting Japanese iris
plant strong divisions and do not allow the roots to dry out. Plant the
rhizomes one to two inches deep in a slight depression. Since the
rhizomes form new roots on top of the old, planting in a depression
allows you to fill with soil around the plants to keep them growing
vigorously for a longer period. Japanese irises will literally grow out
of the ground if not transplanted often enough. It is recommended that
they be reset every three to four years. Do not fertilize newly planted
irises. At the time of planting the roots can be burned by fertilizer.
Wait for a few weeks to feed them until you see new growth. A mulch of
two to three inches is recommended to help conserve moisture and protect
from winter heaving especially on plants that are planted late in the
These spectacular irises are easy if you just remember to give them
ample moisture, acid humus rich soil and generous feeding. Good culture
is more important to Japanese irises than to other types of irises and
they will be taller, more floriferous and have larger flowers if given
Submitted by Carla Lankow for the March, 1998 KCIS Newsletter.