General Information:

The Iris has been a popular perennial in home gardens for many years.   There are
many different varieties of Iris.  I have included general information on the Bearded
German Iris.  The non-bearded Siberian Iris, Japanese Iris, Louisiana Iris, Dwarf Iris,
and the Dutch Iris are also discussed.  The flower of the Iris have 3 upright petals and 3
lower petals (falls).  The upright petals of the Japanese and Louisiana Iris may lay flat
and the flower may not look like an Iris on first glance.  The beard is a fuzzy, fringed
appendage above the lower petals.  Spots or markings on the petals themselves do not
make the flower bearded.  

The Bearded German Iris:

Normally the terms "Bearded Iris" refers to the "German Iris".  The Bearded Iris produce
large flowers with wide petals.  They are available in most colors including multi-color
designs with ruffles, and spots.  The Bearded Iris bloom mid to late spring.  They bloom
after the dwarf Iris, but before any of the other tall Iris types.  There are varieties that
will re-bloom in the fall if the flowers are dead-headed after blooming in the spring.  
They have an inch wide, thick, grass like leaf.  Their root is a rhizome that grows at
ground level with smaller roots shooting downward.  The top of the rhizome is usually
visible if you push the leaves to the side.  The Bearded Iris need a sunny well drained
location.  They are considered hardy in zones 3 to 9.

Every 3 to 5 years the bearded Iris should be divided to keep the patch healthy and
looking good.  The entire root system should be dug up in August after the plants are
done flowering.  Flowers are produced from the new sections of rhizome.  The old
sections should be cut out and discarded.  Any root that shows signs of rot or bug
damage must also be disposed of.  The remaining root should be cut into sections with
at lease 2 leaf buds.  I try to keep as many Y shaped sections as possible.  The roots
should be re-planted the same day they are dug up.  Large patches may be done in
sections.  The rhizome should be planted near surface level.  A small section of the
rhizome around the leaves should be visible above the soil. The fine roots attached to
the rhizome should be planted downward.  In sandy soil, the rhizome may be planted an
inch or two deeper.  If planted too deep the plant will produce leaves, but not flowers.  
Always water the patch well after planting to remove air pockets.  In the absence of rain,
the patch will need water on a regular basis until the roots set themselves.  Watering
too often will cause root rot.  

The Iris borer will attack the Bearded Iris.  The eggs will sit on dead leaves and debris
over the winter, then hatch in the spring.  The larvae will burrow down the Iris leaf and
into the rhizome in the spring.  To control, remove leaves and debris from around the
plants in the fall.  The infested leaf will have a yellow streak where the larvae is boring
its way down.  Crush and discard any infested leaf.  Discard any damaged rhizome
when dividing.

The Siberian Iris:

The Siberian Iris is popular in older gardens.  They will continue to grow for many years
with little maintenance.  The flowers are usually purple or blue in color and have a more
narrow petal than the bearded varieties.  They are hardy in zones 3 to 9.  Their leaves
are thinner and more grass like than the bearded Iris.  The Siberian Iris is not affected
by the Iris borer.  They can be grown in partial shade, but flower better in full sun light.  
They will grow in cooler climates and prefer lots of water in well drained soil.  The root
system is often classified as a rhizome, but grow deeper than the bearded Iris.  The
Siberian Iris will have a big ball of fine roots.  They are divided by cutting the ball of
roots with a sharp spade or large knife.  Older, less productive sections should be
discarded and the remaining sections replanted the same day.  The Siberian Iris
require division less often than the bearded varieties, but older sections will produce
fewer or no flowers.  

Japanese & Louisiana Irises:

The Japanese and Louisiana Irises are non-bearded like the Siberian Iris.  They prefer
warmer climates, zones 5 to 9.  They thrive in wet, acidic, and mucky soils.  They do
well along the edge of a pond.  The Japanese Iris has a ribbed leaf and produce some
of the largest flowers of the Iris family.  The upright flower petals of the Japanese and
Louisiana Iris tend to lay flat and don't look like the traditional bearded Iris flower.  

The Japanese Irises are supposed to give off a chemical that could kill off Irises.  It is
usually recommended that you divide and re-locate the patch every few years.  Care
should be taken not to plant other Iris varieties in areas that recently grew the
Japanese Iris.  

The Dutch Iris & Dwarf Iris:

The Dutch Iris has narrow flower petals compared to the bearded Iris.  The most
popular flower colors are purple, yellow, white, and orange.  The Dutch Iris grow from a
bulb rather than a rhizome root system.  They are supposed to multiply fairly quick.  
They may be divided to spread the patch, but usually grow fine without dividing.  The
Dutch Iris is hardy in zones 5 to 9.  It is usually recommended to use 2 inches of winter
mulch in zone 5.  The Dutch Iris bloom late spring to early summer.  They are the last
type of Iris to bloom.  The only exception would be the second blooming of re-blooming
bearded varieties.  They may be planted in early spring or fall.  I personally have never
grown any, but plan to put in a patch this spring.

The Dwarf Iris also grow from bulbs planted in the fall.  They bloom in early spring
before any other Iris variety.  They only grow about 6 inches tall and usually have
flower colors of blue, purple, and yellow.  They blend in with the crocus and other
spring bulbs, but have a six petal flower like other Irises.  The Dwarf Irises are hardy in
zones 4 to 9.   
Gardener's Supply Company
Site Disclaimer:

This page was developed to share my gardening and landscaping experience with
others.  The site contains only general information on different plants.  I do not
guarantee all information to be accurate.  I do not accept any responsibility for
anyone's growing success.  Please consult with your plant or seed supplier for detailed
planting instructions.
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Gardening > Irises