Re: japanese iris
In a message dated 96-06-26 19:25:00 EDT, you write:
>can anyone tell all they know about japanese irises and how to get
>them to bloom. i have about 12 ji. i planted them this past fall. does
>it take a whole season for them to mature before they bloom? what type
>of weather do they like? just let me know something.....john....thanks
6/26/96 10:34 P.M.
I am going to attempt to answer your questions on Japanese irises by quoting
"Culture for Japanese Iris" from the 1996 Ensata Gardens catalog.
To quote Ensata, "No other iris is influenced to as great a degree by culture
as are the Japanese Iris. Good culture will increase height, branching,
flower size, and quantity and quality of bloom. No other factor will be a
greater influence than water and its quality (pH and /or salts). A lack of
moisture will stunt the plants and produce miniature blooms. An abundance of
water and manure can produce 4-5 foot tall bloom stalks! JI need six hours of
full sun to bloom properly."
"JI require ample moisture, especially up to bloom time, and you will be
rewarded with much healthier plants and bloom next year if the plants are
kept watered all summer long. We want to say "wet" in spring and "moist" the
rest of the year. Never let the soil dry out. Depending on your soil, 1-2" of
water and/or rain per week is recommended; older clumps will need more water
than new divisions. They do very well near water or where the water table is
a short distance below the surface, as beside a stream or pond."
"Japanese iris prefer a rich soil with ample organic matter to help in water
retention as well as adding nutrients. The soil pH should be slightly acid
(5.0 to 6.5). Attention must also be given to the pH of your irrigation
water, which can gradually raise the pH of your soil. An indication of too
high a pH is the gradual yellowing of the leaves. The soil pH can be lowered
by the addition of granular ferrous sulphate (iron sulfphate) or agricultural
"Japanese iris are heavy feeders. Depending on your soil, a liberal
application of fertilizer in spring and just before or after bloom is
beneficial. Most soils need more nitrogen, and JI like nitrogen. Water
soluble acid fertilizer, such as Miracid, is good for quick action but only
lasts for 2-3 weeks. The preparation of your iris bed with compost or manure
will be a good start for your JI, but do not use granular fertilizer until
they are established. Also be careful not to let your plants dry out after
fertilizing, as this will quickly burn plant roots. Virgin soil (virgin to
JI) will produce your best plants. Try not to replant JI divisions back in
the same soil where JI have grown for three or more years. Plant divisions
12-18" apart; 18-24" if you don't want them crowded in three years. The
rhizome should be planted 2-3 inches deep. You can plant them in a depression
which will help catch and hold more water; fill the depression with mulch.
New roots form above the old roots each year, by the time the crown grows to
the surface and roots can be seen, it is time to dig and divide the plant.
Plants under good culture require division every 3 to 4 years. Your best
bloom will be on 2 and 3 year old clumps."
"Japanese iris can be transplanted almost anytime from spring until fall if
you can keep the transplants wet for the rest of the year, and the
temperatures are below 90F for a month afterwards. The best time for you is a
combination of your climate and your gardening practices! Mid-spring to right
after bloom is the best time for us [Ensata Gardens is in Galesburg,
Michigan]. Hot and/or drier regions may have better luck with fall planting.
When dividing, cut back 3/4 of the foliage and plant 2-4 fan divisions. Keep
the transplants well watered until they are well established. Of course we
recommend keeping them well watered all year! DO NOT let the rhizomes or
roots dry out during transplanting: soak in a bucket of water up to 48
"We recommend heavy mulching year round: 2-3 inches. The mulch helps to
conserve moisture, keep the soil cooler, and reduce heaving of fall
transplants. Remove the old foliage which may contain borer eggs or foliage
thrips. These two main pests of JI can be controlled, where warranted, with
systemic insecticides. We use Cygon. Discuss this topic with other gardeners
in your local iris club."
End of quote from Ensata Gardens.
Note: Ensata Gardens is operated by Bob Bauer and John Coble. They are both
leading experts in the production and cultivation of Japanese Irises. The
address for Ensata Gardens is 9823 E. Michigan Avenue, Galesburg, MI 49053.
They have a color catalog for $2.00.
We find here in Maine that the JI's do not bloom heavily the first year
following planting. Some don't bloom at all the first year, but many do. Our
best bloom here is usually in the second or third year after planting.
Hope this helps to address some of your questions, John.
Ted White Minot, Maine USDA Zone 5 AIS Region 1