|
Arils & Arilbred
Iris
The "secret" to growing any type of iris is to
find out what works for others who have the same growing
conditions and emulate their practices. There are excellent
resource books available including THE WORLD OF IRIS, MAGIC
OF IRISES by Barbara Perry Lawton, and THE GARDENER’S
IRIS BOOK by Bill Shears. Only basic starter tips are provided
here. For Aril and Aril-bred Iris, Sharon McAllister is an
excellent source of information. The irises that fall
within the horticultural classes of aril and arilbred irises
are so very different from each other and so variable that
there must be some understanding of the entire collective
group in order to grasp the particulars.
The Aril iris include five (5) groupings, with the two major
groups being Oncocyclus and Regelia Irises. The Oncocyclus
are true desert dwellers, found in the mountain ranges of
Turkey, Iran, and the Caucasus or in the deserts of the Middle
East and Asia Minor. The Regelia are more tolerant of moisture
than the Oncocyclus Iris. The Regelia are not as well adapted
to the desert and may be found in mountain valleys in southwest
and central Asia.
The word "arilbred" refers to hybrids from crosses
between the Tall Bearded iris with the Oncocyclus or the
Regelia iris. It has been suggested to treat Aril Bred Iris
(ABs) the same as Tall Bearded Iris (TBs) with perhaps some
better drainage. ABs are more susceptible to leaf spot and
rhizome rot than TBs. Beginners may want to experiment with
growing ¼ breds and ½ breds before tackling
the ¾ breds and the pure arils. Another wise choice
is to choose varieties that have proven to be good growers.
When to Plant: The best time for planting arilbred
irises is during the dormancy period. The exact time of the
year will depend on the climate. Planting during summer heat
is stressful, and planting too late in the fall prior to
severe winter weather is stressful. It is best to plant as
summer fades into the cooler days of autumn, when the plant
starts to break dormancy.
Where to Plant: Aril and arilbreds are more
difficult to grow in parts of the United States where the
summers are moist. They are more easily grown in warm, dry
regions of the country, especially in desert-like areas such
as Arizona and New Mexico. Raised beds or sloped beds may
be advantageous provided these offer good drainage. Select
an area with plenty of sunshine and good drainage. In the
desert and high altitude areas where the sunshine is intense,
afternoon shade is suggested. Soil
Preparation: Good Drainage is essential to
growing arils and arilbred iris. If the soil is acid or neutral,
add limestone to increase the pH. Arils and arilbreds prefer
a more alkaline soil than do bearded iris. The alkaline soil
needs to contain a good amount of calcium and magnesium,
which can be obtained by using slaked lime or ground limestone.
Dolomitic limestone, which contains magnesium, is especially
good. The soil must be highly fertile and rich in mineral
nutrients. Organic matter, such as well-prepared compost,
is beneficial.
Distance Apart: Giving them more space for
circulation is suggested. These iris resent crowding.
Watering: If summers tend to be dry in your region,
stop watering and allow the plants to go dormant during the
hot dry months. Begin withholding water right after the blooming
season. If summers are excessively wet, arils can be protected
from excessive water using overhead awnings or canopies.
The key to growing is providing good drainage.
Fertilizing: Arilbreds are heavy feeders and
benefit from regular fertilizing. Feeding with soluble fertilizer
having high potash and phosphate rating may be useful.
Bloom Season: Arilbred iris bloom with the
Standard Dwarf and Intermediate Bearded iris.
Moving & Thinning: Many of the arils and
arilbreds increase rapidly and require dividing annually
or every other year to avoid overcrowding. Again, thin and
replant when summer days begin to cool and before winter
days begin.
Pests & Diseases: Arils
and arilbreds are subject to the same array of diseases
and pests as Tall Bearded Iris – including attacks
by aphids, whitefly, iris borers and other insects, and
by leaf spot, rhizome rot and other fungi, bacteria and
virus.
Return to Top of Page
Spuria Iris
Spuria are beardless
iris, originating from the Mediterranean area of Europe.
They are also seen in lesser numbers in England, Denmark,
Russia, Afghanistan and western China. Spuria iris are
one of the tallest of iris, reaching a height of 5 feet
or more. Experience
has shown that spuria iris perform better in areas of the
country where the summer months are dry.
When to Plant: Spuria are dug in the fall before
they start showing signs of new growth. Rhizomes must be
washed well and placed damp in a plastic bag for storage
in the refrigerator, NOT in the freezer. Plant as soon as
possible.
Where to Plant: Spuria
thrive in full sun best, but will do well on half a day’s
sun throughout the year. They will tolerate partial shade,
especially in areas that have extremely high temperatures
in the summer. Soil
Preparation: Spuria prefer a neutral to slightly
alkaline soil and they must have good drainage. Enrich soil
by adding alfalfa and manure. Heavier clay soil is much better
than fine sandy soil.
Basic Planting
Steps: Some spuria are difficult
to establish. Basically spuria need water, manure, and mulch
to become established. Begin the planting by making sure
the soil will allow for good drainage and is enriched. Then
make a hole about two inches below the surface. Add fertilizer
(14-14-14 is suggested) to this hole. Then put lots of water
into this hole. Finally add the rhizome, cover with soil
and mulch. Watering this new spuria rhizome from the top
of the soil is not sufficient for establishing a clump. Mulch
spuria the first year of growth. Saw dust is the best mulch
to use. After the clump is established, the mulch may be
removed during the blooming season.
Distance Apart: Space spuria far enough apart
to grow in the same location for years as Spuria irises resent
being transplanted. Spacing spuria rhizomes three feet apart
is suggested.
Watering: Water regularly from October through
the bloom season until about July 1st. However
do not let them sit in pools of water. During the hot summer,
spuria can be allowed to go dormant by withholding water.
If spuria do go dormant, be sure NOT to water as this will
cause rot. Too much moisture combined with summer heat causes
rot that damages the new growth. Foliage of the summer-dormant
types can be cut back to the ground for garden neatness after
the foliage dies down about the first of August without harming
the plant growth. The species I. carthalinae will remain
green all summer long – it will not go dormant.
Fertilizing: Spuria are very heavy feeders.
Incorporating plenty of barnyard manure and / or commercial
fertilizer into the soil is advisable. Ordinary lawn fertilizer
(10-10-10) works well to feed the spuria in the spring and
again in the fall.
Bloom Season: Spuria usually do not bloom the
first year after planting. The second year should produce
several bloom stalks. The bloom time is one to two weeks
after the tall bearded irises.
Spuria seem to set seed easily and are somewhat easy to
grow from seed. Bees are more attracted to spuria than other
iris; thus pollination and seed production is more prominent
with spuria. Keep an eye open for unwanted pollination.
General Garden
Care: Virus affects some Spuria
irises, although it is seldom very debilitating under good
cultural conditions. It can cause stunting or striping of
the plant and petals. The only serious disease is mustard
seed fungus or crown rot. Soaking rhizomes in a 5% sodium
hypochlorite solution and thoroughly mixing Terrachlor into
the soil before planting are effective controls. Also, dust
or spray annually in the summer for prevention. It is much
easier to prevent the mustard seed fungus than to get rid
of it once the iris is affected. Watering spuria in August
is an easy way for spuria to become affected with fungus,
so use Terrachlor as a routine measure to prevent instead
of treat for mustard seed fungus.
Moving & Thinning: Although
the fall is generally thought to be the best time for transplanting,
they may be transplanted at other times if you are careful
not to let the roots or rhizomes dry out. Storing spuria
rhizomes in the refrigerator before replanting may trigger
faster growth and earlier bloom. Dip the mature rhizome in
a fungicide and store them in plastic bags in the refrigerator
for several weeks to get this response.
Return to Top of Page
Siberian Iris
Siberian irises are among the easiest of all types of iris
to raise. They are also the most adaptable irises for the
perennial border and for landscaping. Their foliage is attractive
all year, even after the first frost when it turns rusty
red-brown. Siberian irises are primarily found in Central
Europe and Asia.
When to Plant: Best time to plant Siberians
is in September. Plant immediately after receiving the rhizomes.
Where to Plant: Siberians are adaptable and
hardy. They love full sun but will grow in light shade. In
areas of extreme sun and heat, it is suggested that Siberians
have some afternoon shade protection. Plant where they will
receive at least three hours, preferable six hours of full
sun daily. Because watering is similar to other garden perennials,
plant Siberian iris with daylilies or similar plants.
Soil Preparation: Siberians prefer a
rich acid soil with lots of organic matter, although they
will grow almost anywhere. Soil pH needs to be mildly acidic
pH (6.5-7.0). If the soil is over 7.5 pH, work in sulfur,
or acidic organic material such as pine needles or peat to
help increase acidity. In areas where the groundwater is
alkaline, repeated acidification will be necessary. An organic
mulch will benefit the plants in summer by retaining moisture
and cooling of the soil. A mulch in the winter can help prevent
heaving and thawing problems.
Basic Planting
Steps: Siberian
rhizomes will arrive moist, wrapped in paper toweling,
cloaked with plastic, and rubber banded to keep them moist
until planting time. Two or four fan divisions are recommended
for planting and the roots must be kept moist. Plant the
rhizomes one inch deep (slightly deeper in sandy soil).
Plant 15" to 18" apart.
Watering: Siberians
like lots of moisture in the spring and can survive dry
periods in late summer months, but clumps will be healthier
if kept moist all summer. Siberians do best if given a
minimum of one inch of water per week during the growing
season. They can tolerate drought. Too much water is one
of the Siberian’s worst enemies.
Fertilizing: An application of fertilizer higher
in nitrogen in the Spring, and a second application of a
balanced fertilizer (10-10-10) or (14-14-14) at the end of
the bloom season. Foliar feedings monthly with a soluble
fertilizer such as Miracid is suggested.
Bloom Season: Siberians normally bloom at the
end of the tall bearded season, 24-34 inches tall. General
Garden Care: In the late fall cut the foliage back
to the ground. After bloom, remove the bloom stalks or the
blossom heads to prevent seeds from forming. Siberian are
more resistant to disease than most other garden irises.
They may get iris borer that can be treated with Cygon 2E
in the spring. Other than the borer, Siberians are almost
disease free.
Moving & Thinning: Some literature suggests
digging and dividing right after bloom. Other literature
suggests early fall (September) as the best time to thin
clumps. Transplants must be kept moist during the thinning
process. Literature suggests dividing Siberian iris after
4 or 5 years if increasing the number of clumps is desired.
Otherwise, clumps can grow undisturbed for several years,
dividing only with overcrowding conditions, when vigor declines,
or when blooms get smaller.
Return to Top of Page
Japanese Iris
When to Plant: Japanese iris can be planted
and transplanted almost anytime from spring until fall if
the transplants are kept wet for the rest of the year and
the temperatures are below 90 degrees F for a month afterwards.
For regions with hot and dryer summers, the fall will be
a better planting time.
Where to Plant: Japanese iris need six hours
of full sun to bloom properly. In the hottest areas, afternoon
shade is suggested. Soil
Preparation: Japanese
iris prefers 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
– 6.5). Attention must be given to the pH of your water,
which can gradually raise the pH of your soil. An indication
of too high pH is the gradual yellowing of the leaves. The
addition of granular ferrous sulfate (iron sulfate) or agricultural
sulfur can lower the soil pH. The preparation of your iris
bed with compost or manure will be a good start for the JI
bed, but do not use granular fertilizer until the plants
are established. Leaves, pine needles, grass clippings, straw
or sawdust are all good soil amendments. Basic Planting
Steps: Plant
the divisions 12-18 inches apart. Plant the rhizome 2-3
inches deep. They can be planted in a depression that will
help catch and hold more water; fill the depression with
mulch. Heavy
mulching (2-3 inches) is recommended year round.
Watering: Japanese
iris require large amounts of water during their
growth and flowering period; however, the plant should
not be allowed to stand in water, especially in winter. |
|
Quality of water (pH and / or salts) is the greatest influence
upon the Japanese Iris plant. A lack of moisture will stunt
the plants and produce miniature blooms. An abundance of
water and manure can produce four to five foot tall bloom
stalks. JI must be kept watered all summer long. Never let
the soil dry out. Mulch the plantings. Depending on the soil,
1-2 inches of water per week is recommended. Older clumps
need more water than new divisions. They do very well beside
a stream or pond.
One good method of watering is to
form a basin around the plant. Slightly elevate the
plant with the crown one-inch below the soil. Plastic
or aluminum lawn edging works well for a basin. Flood
the basin two to three times each watering. Applying
aquarium water can serve to keep rhizomes wet and
to keep pH lowered. |
Japanese irises are NOT bog plants in northern zones (zones
3-6). One of the biggest misconceptions about Japanese Iris
come from seeing photos of flooded fields in Japan. The Japanese
flood the fields at bloom time for the esthetic setting and
the beauty of the blooms reflected in the water. When JI
are planted in a bog and if the water freezes over the top
of the crowns the plants may suffocate and die. Artificial,
plastic lined bogs have produced mixed results. If using
plastic lined bogs, it is best to put some holes in the bottom
and allow the water drainage to be retarded, but not prevented.
If JI are grown in pots in ponds, the pots need to be lifted
after frost, foliage cut off and the pots buried in the garden.
These pots can be returned to the pond the next spring.
Fertilizing: Japanese iris are heavy feeders
and fertilizing three times a year is suggested. A liberal
application of fertilizer in the spring and just before or
after bloom is beneficial. A third application in the fall
is also beneficial. JI like nitrogen. Water-soluble acid
fertilizer, such as Miracid (acid type that is used for azaleas
and camellias) is good for quick action but only lasts for
2-3 weeks. An all purpose fertilizer such as 5-10-10 can
be used and the acid condition provided by the addition of
soil sulfur, aluminum sulfate or small pieces of aluminum
foil buried just under the soil surface. One half of one
pound of soil sulfur per 100 square feet of planting area
applied yearly in early fall is ample. Oak leaves, pine needles
and peat moss help to supply the acid condition these plants
favor, and the more leaves which are used, the less sulfur
is required. Do not let the plants dry out after fertilizing
because this will quickly burn the plant roots.
Bloom Season: Successfully growing JI requires
a lot of patience. Under the best of conditions, spectacular
display is not attained until the second or third year. JI
will bloom shortly after the Tall Bearded Iris.
General Garden
Care: Remove the old foliage
after the first frosts. Destroy the old foliage that may
contain borer eggs or foliage thrips. The two main pests
of JI can be controlled, where warranted with systemic insecticide
such as Cygon 2E or Isotox.
Moving & Thinning: Try
not to replant Japanese Iris back in the same soil where
JI have grown for three or more years. New roots form above
the old roots each year, by the time the crown grow to
the surface and the roots can be seen, it is time to dig
and divide the plant. Plants under good culture require
division every 3-4 years. When bloom sizes and plant height
decrease, it is time to divide. When dividing, cut back ¾ of the foliage and plant 2-4
fan divisions. Keep the transplants well watered until they
are well established. Do NOT let the rhizomes or the roots
dry out during transplanting – soak in a bucket of
water up to 48 hours.
Return to Top of Page
Louisiana Iris
When to Plant: Plant Louisiana iris in the
fall (September) after the temperature has cooled less than
100 degrees and before frost.
Where to Plant: Plant
Louisiana iris in good soil with at least half a day’s
shade. Morning sun or filtered sun is acceptable. Good
drainage is not required since LA will grow in mud or water.
Borders of boards, bricks, or rocks helps hold moisture
and mulch materials. Plant rhizomes at or slightly below
ground level and shade with a layer of mulch or soil in
summer, especially in dry hot climates when planting in
full sun. They do fine in the ground, in large pots, and
are fantastic when the pots are submerged in a fishpond
or other garden water feature.
Soil Preparation: Prepare beds at least a month
in advance. For 100 sp. ft, use 2-3 lbs of treble super phosphate,
3 lbs. Soil sulfur and 2 lbs of nitrogen (ammonium sulphate).
If using ammonium phosphate instead of treble super phosphate,
skip the ammonium sulphate. The soil sulphur will increase
acidity of the alkaline soil. To counteract yellowing leaves,
use iron chelate according to package directions. Dig in
peat moss, compost, straw and/or rotted manure to loosen
soils and hold moisture. Some literature suggests adding
clay to better support the heavy foliage system.
Watering: Water well first before planting
the first time and keep bed damp all year long. After bloom
season, the plants need to be watered well at least weekly.
Water every day if necessary to keep LAs always damp. Soaking
the bed is suggested. Growth will slow down in the summer,
but the plants should not be allowed to lose their leaves
and go dormant. LAs, being native to bogs, like to be continuously
wet. LAs have a fondness for moisture and many varieties
can tolerate standing water. But the water levels may need
to be dropped in the winter because letting the plants freeze
in ice during the winter is fatal.
Mulching is absolutely
vital to Louisiana Irises that are being grown in garden
beds and borders. Mulch at a depth of 3 inches will help
to conserve water and protect the rhizomes from sunscald.
A mulch depth of 8-10" added before really
cold weather set in may be needed in northern areas where
freezing weather is expected. Pine needles make excellent
mulch, as do well-chopped autumn leaves.
Fertilizing: Louisianas
are heavy feeders. After frost danger is over, start fertilizing.
You can use Miracid at ½ rate by sprinkling lightly
around each plant or over the complete bed every two weeks
up to bloom season and again after bloom season just once.
Do not fertilize during the bloom period. Louisiana irises
like to feed more during the year than other varieties.
Add iron to keep color in the foliage. Established plants
should be side dressed in Spring and Fall.
Bloom Season: Louisiana irises bloom at the
same time as the Tall Bearded Iris.
General Garden
Care: Cut spent bloom stalks
if not being kept for the seedpods. Remove dead leaves only
after they are ready to fall away from the rhizomes. Some
varieties stay green all summer and some go completely dormant.
Most, if kept well mulched and watered, will remain green
all summer. Provide shade over rhizomes in the summer to
cut down on sun scald that reduces increase and future bloom.
Moving & Thinning: Transplant
or thin Louisiana iris in September. Wash plants and roots
well, place in plastic bags and store in the refrigerator – NOT the freezer.
Always keep the roots long and damp. Most clumps need to
be divided about every other year for best results. Leave
enough space between plants to allow for long rhizomes that "travel" or "walk" as
much as a foot from the old rhizome. Cut the foliage back
and water to settle the soil around the roots. Pin the rhizomes
to the ground when planting in shallow ponds or along creeks.
|