Japanese Irises have thick rhizomes, giving rise to fans of sword-shaped, usually broad green leaves, and simple or branched flower stems. Most bear multiple flowers per stem. The flowers have well-developed standards and falls. Avoid high nitrogen fertilizer. Keep mulches away from leaves and rhizomes. Water moderately during growth periods; keep dry while dormant. Japanese irises grow to 3 feet and produce flowers, 4 to 8 inches across, in midseason.

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Iris kaempferi - Japanese Iris
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Iris kaempferi - Japanese Iris
Japanese Irises have thick rhizomes, giving rise to fans of sword-shaped, usually
broad green leaves, and simple or branched flower stems. Most bear multiple
flowers per stem. The flowers have well-developed standards and falls. Avoid
high nitrogen fertilizer. Keep mulches away from leaves and rhizomes. Water
moderately during growth periods; keep dry while dormant. Japanese irises grow
to 3 feet and produce flowers, 4 to 8 inches across, in midseason.
Important Info : May cause severe discomfort if ingested. Sap may cause
skin irritation.
How to Grow this Plant:
Characteristics
Family: Iridaceae
Height: 1.5 ft. to 3 ft.
Size:
Width: 0.5 ft. to 1 ft.
Plant Category: bulbous plants, landscape, perennials,
Plant Characteristics: poisonous,
Foliage Characteristics: coarse leaves, deciduous, poisonous,
Foliage Color: green,
Flower Characteristics: erect, long lasting, showy, single,
Flower Color: Purple, Blue, Red, Whites,
Tolerances: deer,
Requirements
Bloomtime Range: Late Spring to Early Summer
USDA Hardiness Zone: 3 to 9
AHS Heat Zone: Not defined for this plant
Light Range: Dappled to Full Sun
pH Range: 6 to 7
Soil Range: Sandy Loam to Clay Loam
Water Range: Normal to Normal
Plant Care
Fertilizing
Fertilization for Young Plants
Young plants need extra phosphorus to encourage good root development. Look for a fertilizer that has
phosphorus, P, in it(the second number on the bag.) Apply recommended amount for plant per label directions
in the soil at time of planting or at least during the first growing season.
Fertilization for Established Plants
Established plants can benefit from fertilization. Take a visual inventory of your landscape. Trees need to be
fertilized every few years. Shrubs and other plants in the landscape can be fertilized yearly. A soil test can
determine existing nutrient levels in the soil. If one or more nutrients is low, a specific instead of an all-purpose
fertilizer may be required. Fertilizers that are high in N, nitrogen, will promote green leafy growth. Excess
nitrogen in the soil can cause excessive vegetative growth on plants at the expense of flower bud development. It
is best to avoid fertilizing late in the growing season. Applications made at that time can force lush, vegetative
growth that will not have a chance to harden off before the onset of cold weather.
Fertilization for Annuals and Perennials
Annuals and perennials may be fertilized using: 1. water-soluble, quick release fertilizers; 2. temperature
controlled slow-release fertilizers; or 3. organic fertilizers such as fish emulsion. Water soluble fertilizers are
generally used every two weeks during the growing season or per label instructions. Controlled, slow-release
fertilizers are worked into the soil usually only once during the growing season or per label directions. For
organic fertilizers such as fish emulsion, follow label directions as they may vary per product.
Light
Conditions : Partial Shade
Partial Shade is defined as filtered light found beneath trees with high limbs. Partial shade usually offers some
protection from direct afternoon sun.
Conditions : Dappled Light
Dappled Light refers to a dappled pattern of light created on the ground, as cast by light passing through high
tree branches. This is the middle ground, not considered shady, but not sunny either. Dappled remains constant
throughout the day.
Conditions : Part Sun
Part Sun refers to filtered light, with most sun being received during the afternoon hours. Shade usually occurs
during the morning hours.
Conditions : Light Conditions
Unless a site is completely exposed, light conditions will change during the day and even during the year. The
northern and eastern sides of a house receive the least amount of light, with the northern exposure being the
shadiest. The western and southern sides of a house receive the most light and are considered the hottest
exposures due to intense afternoon sun.
You will notice that sun and shade patterns change during the day. The western side of a house may even be
shady due to shadows cast by large trees or a structure from an adjacent property. If you have just bought a
new home or just beginning to garden in your older home, take time to map sun and shade throughout the day.
You will get a more accurate feel for your site's true light conditions.
Conditions : Filtered Light
For many plants that prefer partially shady conditions, filtered light is ideal. Good planting sites are under a mid
to large sized tree that lets some light through their branches or beneath taller plants that will provide some
protection.
Conditions : Partial Sun, Partial Shade
Part sun or part shade plants prefer light that is filtered. Sunlight, though not direct, is important to them. Often
morning sun, because it is not as strong as afternoon sun, can be considered part sun or part shade. If you live in
an area that does not get much intense sun, such as the Pacific Northwest, a full sun exposure may be fine. In
other areas such as Florida, plant in a location where afternoon shade will be received.
Conditions : Full to Partial Sun
Full sunlight is needed for many plants to assume their full potential. Many of these plants will do fine with a
little less sunlight, although they may not flower as heavily or their foliage as vibrant. Areas on the southern and
western sides of buildings usually are the sunniest. The only exception is when houses or buildings are so close
together, shadows are cast from neighboring properties. Full sun usually means 6 or more hours of direct
unobstructed sunlight on a sunny day. Partial sun receives less than 6 hours of sun, but more than 3 hours. Plants
able to take full sun in some climates may only be able to tolerate part sun in other climates. Know the culture of
the plant before you buy and plant it!
Conditions : Light and Plant Selection
For best plant performance, it is desirable to match the correct plant with the available light conditions. Right
plant, right place! Plants which do not receive sufficient light may become pale in color, have fewer leaves and a
"leggy" stretched-out appearance. Also expect plants to grow slower and have fewer blooms when light is less
than desirable. It is possible to provide supplemental lighting for indoor plants with lamps. Plants can also receive
too much light. If a shade loving plant is exposed to direct sun, it may wilt and/or cause leaves to be sunburned
or otherwise damaged.
Conditions : Full Sun
Full Sun is defined as exposure to more than 6 hours of continuous, direct sun per day.
Watering
Conditions : Regular Moisture for Outdoor Plants
Water when normal rainfall does not provide the preferred 1 inch of moisture most plants prefer. Average water
is needed during the growing season, but take care not to overwater. The first two years after a plant is installed,
regular watering is important. The first year is critical. It is better to water once a week and water deeply, than to
water frequently for a few minutes.
Conditions : Moist and Well Drained
Moist and well drained means exactly what it sounds like. Soil is moist without being soggy because the
texture of the soil allows excess moisture to drain away. Most plants like about 1 inch of water per week.
Amending your soil with compost will help improve texture and water holding or draining capacity. A 3 inch
layer of mulch will help to maintain soil moisture and studies have shown that mulched plants grow faster than
non-mulched plants.
Conditions : Outdoor Watering
Plants are almost completely made up of water so it is important to supply them with adequate water to maintain
good plant health. Not enough water and roots will wither and the plant will wilt and die. Too much water
applied too frequently deprives roots of oxygen leading to plant diseases such as root and stem rots. The type of
plant, plant age, light level, soil type and container size all will impact when a plant needs to be watered. Follow
these tips to ensure successful watering:
* The key to watering is water deeply and less frequently. When watering, water well, i.e. provide enough water
to thoroughly saturate the root ball. With in-ground plants, this means thoroughly soaking the soil until water has
penetrated to a depth of 6 to 7 inches (1' being better). With container grown plants, apply enough water to
allow water to flow through the drainage holes.
* Try to water plants early in the day or later in the afternoon to conserve water and cut down on plant stress.
Do water early enough so that water has had a chance to dry from plant leaves prior to night fall. This is
paramount if you have had fungus problems.
* Don't wait to water until plants wilt. Although some plants will recover from this, all plants will die if they wilt
too much (when they reach the permanent wilting point).
* Consider water conservation methods such as drip irrigation, mulching, and xeriscaping. Drip systems which
slowly drip moisture directly on the root system can be purchased at your local home and garden center.
Mulches can significantly cool the root zone and conserve moisture.
* Consider adding water-saving gels to the root zone which will hold a reserve of water for the plant. These can
make a world of difference especially under stressful conditions. Be certain to follow label directions for their
use.
Conditions : Normal Watering for Outdoor Plants
Normal watering means that soil should be kept evenly moist and watered regularly, as conditions require.
Most plants like 1 inch of water a week during the growing season, but take care not to over water. The first
two years after a plant is installed, regular watering is important for establishment. The first year is critical. It is
better to water once a week and water deeply, than to water frequently for a few minutes.
Planting
Preparing Garden Beds
Use a soil testing kit to determine the acidity or alkalinity of the soil before beginning any garden bed
preparation. This will help you determine which plants are best suited for your site. Check soil drainage and
correct drainage where standing water remains. Clear weeds and debris from planting areas and continue to
remove weeds as soon as they come up.
A week to 10 days before planting, add 2 to 4 inches of aged manure or compost and work into the planting
site to improve fertility and increase water retention and drainage. If soil composition is weak, a layer of topsoil
should be considered as well. No matter if your soil is sand or clay, it can be improved by adding the same thing:
organic matter. The more, the better; work deep into the soil. Prepare beds to an 18 inch deep for perennials.
This will seem like a tremendous amount of work now, but will greatly pay off later. Besides, this is not
something that is easily done later, once plants have been established.
Planting Bulbs
Plant bulbs at a depth that is three times their height, and at least 1-1/2 bulb-widths apart. Work a little bone
meal fertilizer into the bottom of your hole, and then place the bulb upright in the hole. The more pointed end is
almost always the top. If you have trouble telling which is the top, look for evidence of where a stem or roots
were last year. If in doubt, plant them sideways. Fill in with soil gently, making sure there are no rocks or clods
that would impede the bulb's stem. When planting a great number of bulbs, dig out an area to the specified
depth, place bulbs and replace soil. This ensures that ground has been properly prepared and bulbs are evenly
spaced.
Plant bulbs in natural drifts rather that formal rows: bulbs can fail or be eaten, leaving holes in a formal
arrangement, or will shift with freezing and thawing. If you have trouble with gophers or squirrels eating your
bulbs, try sprinkling red pepper in the holes, covering the bulbs with chicken-wire, surround bulbs with sharp
shards of gravel or other substance, or planting rodent-repelling bulbs like Fritillaria nearby.
Pinching and Thinning Perennials
Once you plant a perennial, it does not mean that you will enjoy years of maintenance-free gardening. Perennials
need to be cared for just like any other plant. One thing that distinguishes perennials is that they tend to be active
growers that have to be thinned out occasionally or they will loose vigor.
As perennials establish, it is important to prune them back and thin them out occasionally. This will prevent them
from completely taking over an area to the exclusion of other plants, and also will increase air circulation thereby
reducing the incidence of diseases like botrytis and powdery mildew.
Many species also flower abundantly and produce ample seed. As blooms fade it is advisable to deadhead your
plant; that is, to remove spent flowers before they form seed. This will prevent your plants from seeding all over
the garden and will conserve the considerable energy it takes the plant to produce seed.
As perennials mature, they may form a dense root mass that eventually leads to a less vigorous plant. It is
advisable to occasionally thin out a stand of such perennials. By dividing the root system, you can make new
plants to plant in another area of the garden or give away. Also root pruning will stimulate new growth and
rejuvenate the plant. Most perennials may be successfully divided in either spring or fall. Do a little homework;
some perennials do have a preference.
Preparing Containers
Containers are excellent when used as an ornamental feature, a planting option when there is little or no soil to
plant in, or for plants that require a soil type not found in the garden or when soil drainage in the garden is
inferior. If growing more than one plant in a container, make sure that all have similar cultural requirements.
Choose a container that is deep and large enough to allow root development and growth as well as proportional
balance between the fully developed plant and the container. Plant large containers in the place you intend them
to stay. All containers should have drainage holes. A mesh screen, broken clay pot pieces(crock) or a paper
coffee filter placed over the hole will keep soil from washing out. The potting soil you select should be an
appropriate mix for the plants you have chosen. Quality soils (or soil-less medias) absorb moisture readily and
evenly when wet. If water runs off soil upon initial wetting, this is an indicator that your soil may not be as good
as you think.
Prior to filling a container with soil, wet potting soil in the bag or place in a tub or wheelbarrow so that it is
evenly moist. Fill container about halfway full or to a level that will allow plants, when planted, to be just below
the rim of the pot. Rootballs should be level with soil line when project is complete. Water well.
Planting Perennials
Determine appropriate perennials for your garden by considering sun and shade through the day, exposure,
water requirements, climate, soil makeup, seasonal color desired, and position of other garden plants and trees.
The best times to plant are spring and fall, when soil is workable and out of danger of frost. Fall plantings have
the advantage that roots can develop and not have to compete with developing top growth as in the spring.
Spring is more desirable for perennials that dislike wet conditions or for colder areas, allowing full establishment
before first winter. Planting in summer or winter is not advisable for most plants, unless planting a more
established sized plant.
To plant container-grown plants: Prepare planting holes with appropriate depth and space between. Water
the plant thoroughly and let the excess water drain before carefully removing from the container. Carefully loosen
the root ball and place the plant in the hole, working soil around the roots as you fill. If the plant is extremely root
bound, separate roots with fingers. A few slits made with a pocket knife are okay, but should be kept to a
minimum. Continue filling in soil and water thoroughly, protecting from direct sun until stable.
To plant bare-root plants: Plant as soon as possible after purchase. Prepare suitable planting holes, spread
roots and work soil among roots as you fill in. Water well and protect from direct sun until stable.
To plant seedlings: A number of perennials produce self-sown seedlings that can be transplanted. You may
also start your own seedling bed for transplanting. Prepare suitable planting holes, spacing appropriately for
plant development. Gently lift the seedling and as much surrounding soil as possible with your garden trowel, and
replant it immediately, firming soil with fingertips and water well. Shade from direct sun and water regularly until
stable.
Diseases : Rhizactonia Root and Stem Rot
Rhizoctonia is a fungus that is found in most soils and enters the plant through the roots or the stem at soil level.
Prevention and Control: First of all, do not overwater and if you suspect Rhizoctonia may be your problem,
decrease watering. If a plant is too far gone (all the leaves from the bottom up are wilted), remove it. If your
plant is in a container, discard the soil too. Wash the pot with a 1 part bleach to 9 parts water solution.
Fungicides can be used, according to label directions. Consult a professional for a legal recommendation of what
fungicide to use.
Pest : Thrips
Thrips are small, winged insects that attack many types of plants and thrive in hot, dry conditions (like heated
houses). They can multiply quickly as a female can lay up to 300 eggs in a life span of 45 days without mating.
Most of the damage to plants is caused by the young larvae which feed on tender leaf and flower tissue. This
leads to distorted growth, injured flower petals and premature flower drop. Thrips also can transmit many
harmful plant viruses.
Prevention and Control: keep weeds down and use screening on windows to keep them out. Remove or
discard infested plants, keep them away from non-infested plants. Trap with yellow sticky cards or take
advantage of natural enemies such as predatory mites. Sometimes a good steady shower of water will wash
them off the plant. Consult your local garden center professional or county Cooperative extension office for legal
chemical recommendations.
Pest : Whiteflies
Whiteflies are small, winged insects that look like tiny moths, which attack many types of plants. The flying
adult stage prefers the underside of leaves to feed and breed. Whiteflies can multiply quickly as a female can lay
up to 500 eggs in a life span of 2 months. If a plant is infested with whiteflies, you will see a cloud of fleeing
insects when the plant is disturbed. Whiteflies can weaken a plant, eventually leading to plant death if they are
not checked. They can transmit many harmful plant viruses. They also produce a sweet substance called
honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.
Possible controls: keep weeds down; use screening in windows to keep them out; remove infested plants away
from non-infested plants; use a reflective mulch (aluminum foil) under plants (this repels whiteflies); trap with
yellow sticky cards, apply labeled pesticides; encourage natural enemies such as parasitic wasps in the garden;
and sometimes a good steady shower of water will wash them off the plant.
Pest : Slugs and Snails
Slugs and snails favor moist climates and are mollusks, not insects. They can be voracious feeders, eating just
about anything that is not woody or highly scented. They may eat holes in leaves, strip entire stems, or
completely devour seedlings and tender transplants, leaving behind tell-tale silvery, slimy trails.
Prevention and control: Keep your garden as clean as possible, eliminating hiding places such as leaf debris,
over-turned pots, and tarps. Groundcover in shady places and heavy mulches provide protection from the
elements and can be favorite hiding places. In the spring, patrol for and destroy eggs (clusters of small
translucent spheres) and adults during dusk and dawn. Set out beer traps from late spring through fall.
Many chemical controls are available on the market, but can be poisonous and deadly for children and pets;
take care when using them - always read the label first!
Fungi : Rusts
Most rusts are host specific and overwinter on leaves, stems and spent flower debris. Rust often appears as
small, bright orange, yellow, or brown pustules on the underside of leaves. If touched, it will leave a colored spot
of spores on the finger. Caused by fungi and spread by splashing water or rain, rust is worse when weather is
moist.
Prevention and Control: Plant resistant varieties and provide maximum air circulation. Clean up all debris,
especially around plants that have had a problem. Do not water from overhead and water only during the day so
that plants will have enough time to dry before night. Apply a fungicide labeled for rust on your plant.
Diseases : Pythium and Phytophtora Root Rot
Rot Rot, Pythium or Phytophthora occurs when soil moisture levels are excessively high and fungal spores
present in the soil, come in contact with the susceptible plant. The base of stems discolor and shrink, and leaves
further up the stalk wilt and die. Leaves near base are affected first. The roots will turn black and rot or break.
This fungi can be introduced by using unsterilized soil mix or contaminated water.
Prevention and ControlRemove affected plants and their roots, and discard surrounding soil. Replace with
plants that are not susceptible, and only use fresh, sterilized soil mix. Hold back on fertilizing too. Try not to over
water plants and make sure that soil is well drained prior to planting. This fungus is not treatable by chemicals.
Rhizoctonia Root and Stem Rot symptoms look similar to Pythium Root Rot, but the Rhizoctonia fungus seems
to thrive in well drained soils.
Weeds : Preventing Weeds and Grass
Weeds rob your plants of water, nutrients and light. They can harbor pests and diseases. Before planting,
remove weeds either by hand or by spraying an herbicide according to label directions. Another alternative is to
lay plastic over the area for a couple of months to kill grass and weeds.
You may apply a pre-emergent herbicide prior to planting, but be sure that it is labeled for the plants you are
wishing to grow. Existing beds may be spot sprayed with a nonselective herbicide, but be careful to shield those
plants you do not want to kill. Non-selective means that it will kill everything it comes in contact with.
Mulch plants with a 3 inch layer of pinestraw, pulverized bark, or compost. Mulch conserves moisture, keeps
weeds down, and makes it easier to pull when necessary.
Porous landscape or open weave fabric works too, allowing air and water to be exchanged.
Miscellaneous
Glossary : Border Plant
A border plant is one which looks especially nice when used next to other plants in a border. Borders are
different from hedges in that they are not clipped. Borders are loose and billowy, often dotted with deciduous
flowering shrubs. For best effect, mass smaller plants in groups of 3, 5, 7, or 9. Larger plants may stand alone,
or if room permits, group several layers of plants for a dramatic impact. Borders are nice because they define
property lines and can screen out bad views and offer seasonal color. Many gardeners use the border to add
year round color and interest to the garden.
Glossary : Naturalizing
Naturalizing refers to planting in a random pattern, much as it would occur in nature. If you spend any time in
the woods, you've probably noticed that plants often grow in groups. The center of the group is dense and
towards the edges, plants are located farther apart. Narcissus bulbs are easy to naturalize if you use this method:
fill a bucket with bulbs and toss them out. Plant them where they fall. You will notice a portion of the bulbs are
close together while the others have scattered farther away.
Glossary : Bulbs
A bulb is a modified, underground stem.
Glossary : pH
pH, means the potential of Hydrogen, is the measure of alkalinity or acidity. In horticulture, pH refers to the pH
of soil. The scale measures from 0, most acid, to 14, most alkaline. Seven is neutral. Most plants prefer a range
between 5.5 and about 6.7, an acid range, but there are plenty of other plants that like soil more alkaline, or
above 7. A pH of 7 is where the plant can most easily absorb the most nutrients in the soil. Some plants prefer
more or less of certain nutrients, and therefore do better at a certain pH.
Getting the Most Out of Cut Flowers
Cut flowers bring the garden into your home. While some cut flowers have a long vase life, most are highly
perishable. How cut flowers are treated when you first bring them home can significantly increase how long they
last.
The most important thing to consider is getting sufficient water taken up into the cut stem. Insufficient water can
result in wilting and short-lived flowers. Bent neck of roses, where the flower head droops, is the result of poor
water uptake. To maximize water uptake, first re-cut the stems at an angle so that the vascular system (the
""plumbing"" of the stem) is clear. Next immerse the cut stems in warm water.
Remember when the flower is cut, it is cut off from its food supply. Once water is taken care of, food is the
resource that will run out next. The plants stems naturally feed the flowers with sugars. If you add a bit of sugar
(1 tsp.) to the vase water, this will help feed the flower stems and extend their vase life.
Bacteria will build up in vase water and eventually clog up the stem so the flower cannot take up water. To
prevent this, change the vase water frequently and make a new cut in the stems every few days.
Floral preservatives, available from florists, contain sugars, acids and bacteriacides that can extend cut flower
life. These come in small packets and are generally available where cut flowers are sold. If used properly, these
can extend the vase life of some cut flowers 2 to 3 times when compared with just plain water in the vase.
Glossary : Viruses
Viruses, which are smaller than bacteria, are not living and do not replicate on their own. They must rely on the
cellular mechanisms of their hosts to replicate. Because this greatly disrupts the cell's functionality, outward signs
of a viral infection result in a plant disease with symptoms such as abnormal or stunted growth, damaged fruit,
discolorations or spots.
Prevention and Control: Keep virus carriers such as aphids, leafhoppers, and thrips under control. These plant
feeding insects spread viruses. Viruses can also be introduced by infected pollen or through plant openings (as
when pruning). Begin by keeping the pathogen out of your garden. New plants should be checked, as well as
tools and existing plants. Use only certified seed that is deemed disease-free. Plant only resistant varieties
and create a discouraging environment by rotating crops, not planting closely related plants in the same area
every year.
Botanical Name listing of Plants
Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Common Name listing of Plants
Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
The alpha listing contain thousands of plants with useful information about your plant of interest. Do you want
to learn how to plant a shrub, tree, perennial or a vine? You can learn how hardy the plant is before you plant
it in your garden. Do you want to know the common name of the plant... it's provided.
How to Fertilize your Trees, shrubs, annuals or perennials and general plant care... WOW!
The following gardening information or garden guide is provided:
Characteristics Requirements
l Cultivar l Bloomtime Range
l Family l USDA Hardiness Zone
l Size l AHS Heat Zone
l Plant Category l Light Range
l Plant l pH Range
l Foliage l Soil Range
l Foliage Color l Water Range
l Flower Characteristics
l Flower Color
l Tolerances
Search the Plant Encyclopedia Index
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