Russ & Nancy's
Tall Bearded Iris Collection
PHOTO CATALOG - HOW TO GROW IRIS - IRIS PROBLEMS - ABBREVIATIONS
|HOW TO GROW IRIS|
|Tall bearded iris are one of the easiest and hardiest perennials to grow. They are available in a rainbow of colors and will reward you with beautiful blooms year after year. You will find these suggestions on growing iris to be simple, and proper care is very easy.|
|WHEN TO PLANT|
|It is best to plant your iris so the roots get well established before the end of your growing season. Plant your new rhizomes as soon as possible after receiving them, and at least six (6) weeks before your first frost. The planting zone map and chart below is a general reference to determine when your first frost date is, please click on the thumbnail view of the map to determine your zone, then refer to the zone chart to determine your approximate first frost dates and deduct 6 weeks from the date in your zone. We normally start shipping starting to zones 1-4 during the first weeks of July, zones 5-7 during the first weeks of August, and zones 8-10 until the middle of September, so if you are in Zones 1-4 please take this into consideration when placing your order. Rhizomes can stay out of the ground for a week or two if necessary as long as they are stored in a cool dry location.|
- Average dates first frost - July 1 to July 31
Zone 2 - Average dates first frost - August 1 to August 31
Zone 3 - Average dates first frost - September 1 to September 30
Zone 4 - Average dates first frost - September 1 to September 30
Zone 5 - Average dates first frost - September 30 to October 30
Zone 6 - Average dates first frost - September 30 to October 30
Zone 7 - Average dates first frost - September 30 to October 30
Zone 8 - Average dates first frost - October 30 to November 30
Zone 9 - Average dates first frost - November 30 to December 30
Zone 10 - Average dates first frost - November 30 to December 30
Zone 11 - Free of frost throughout the year.
|If you are going to be planting your Iris after the six (6) week period before your first frost, we recommend planting your rhizomes in pots and keeping them in a greenhouse until the start of your growing season. Then transplant them to a location as described below.|
|WHERE TO PLANT|
|SUN: Select a sunny location,
preferably where they will get around 3/4 day full sun. If you plant them where they are shaded
for 1/2 the day or more they probably won't bloom. Iris do best in full
sun, but in very hot climates a little shade is ok.
DRAINAGE: Iris like water, but drainage is very important. The rhizome and roots can't survive in soggy soil, they will rot, so make sure you provide your iris bed with good drainage. It is best to avoid areas at the bottom of a slope, or marshy areas where water gathers during wet weather. I recommend areas that have a slight slope to allow the soil to drain well. If your area is totally flat I recommend a raised bed with the addition of some coarse sand to allow the soil to drain well.
|Iris will grow in any good
neutral garden soil, especially in virgin soil that has never had iris in
START by tilling or turning and loosening your soil to a depth of 6" to 8", and turn in a good application of compost. I add around 25-30% compost. If you have very sandy soils you may want to add a little more compost. If you have heavy clay soils, along with the compost you may want to add some coarse sand to improve the needed drainage.
|HOW TO PLANT|
It is best to plant iris rhizomes in rows that are about 2-1/2 to 3 feet apart.
|Newly planted iris need
consistent moisture to encourage root growth, however over-watering can
encourage rot, so they should never be kept soggy. Plants should get
established in 2 - 3 weeks. If in doubt, simply tug lightly on the fan, if
you feel resistance, the roots are digging in, if the plant seems wobbly
like you could easily pull it out, then it needs more time to get
Once they are established, I recommend you switch to deep watering at longer intervals. Frequent over-watering is a common error and WILL cause your iris to rot. Established iris normally can tolerate some drought in mid-summer, but if the iris are re-bloomers they will require a little more water than spring only bloomers. If your re-blooming iris do not receive moisture during a three (3) week period during the summer, they probably won't bloom again until next spring.
METHODS: I found it really does not matter what watering method you use, just be sure you establish a regular watering program that gives water, but not too much water.
Some prefer overhead sprinklers, and this is fine, but make sure you add a 24" to 36" extension to each sprinkler head as your plants grow taller, this will allow water to be distributed evenly.
Some prefer the use of a weeping soaker type garden hose. This conserves water as well as minimizes the chance of disease growth. If using this method, add the hose at the time your rows of rhizomes are planted. The hose can be buried to a depth of 1/2" and placed near the newly planted rhizome.
Some prefer drip systems. This also conserves water as well as minimizes the chance of disease growth. Some with drip systems even rig up fertilizer injectors at the water valve.
These are all great, but the system you select is not as important as this one point: don't over-water your iris.
|Specific fertilizer recommendations depend
on your soil type.
WHEN: Generally in February, a light application of balanced fertilizer (approx. 5-10-10, or 6-to-6, or super phosphate) should be added as a top dressing around each plant. Usually this is done around four (4) to six (6) weeks before the spring bloom. To insure you have blooms next year, it is best to repeat this again about four (4) to six (6) weeks after the spring bloom. If they are re-bloomers, I recommend you repeat this again in the fall. Light application means just a small handful, maybe 1/3 to 1/2 cup, sprinkled around each plant and stirred into the soil. If possible, do this just before rain, or hose the plants clean and wet the soil where all fertilizer was placed, this way any that may have fallen on new growth is washed off, and fertilizer in the soil can be absorbed by the roots.
IMPORTANT: Never use high nitrogen fertilizer, or over fertilize, as this promotes soft growth and WILL cause the rhizome to rot and die.
|It is not recommended to cut the green iris leaves since plant food is stored in them. Keep your iris beds free of weeds and debris, so that your iris can bask in the sun unobstructed. Old and diseased leaves should be removed as they develop. I do this once a month. Old flower stalks should be cut off within about 6" of the rhizome. Leaves and stalks can be added to a mulch bin, or mulch pile, but only if they were healthy, always dispose of diseased leaves and stalks so you don't spread any diseases to other plants.|
|Iris need to be thinned or divided before they become overcrowded, usually every three (3) to four (4) years. If iris are allowed to become too overcrowded the bloom will suffer, and disease problems may increase. It is best to transplant during the iris dormant season in July-August-September, at least 6 weeks before your first frost, this allows them to root sufficiently before winter. Dig the entire clump out of the ground, wash soil off the roots, separate the rhizomes by cutting at intersections, and trim leaves into a fan shape about six inches (6") long. The fan will allow the plant to maintain it's food supply, which is in the leaves, yet it will prevent dehydration during this 4-6 week period. Discard all rhizomes without leaves. Replant rhizomes with fans.|
|If you are in a freezing cold climate area, it may be a good idea to cover your bearded iris during the coldest months of the winter to protect them against severe cold weather, and prevent heaving of the rhizomes. Rhizomes can heave above the soil line, and the top of it can freeze, then thaw, then freeze, again and again, usually during the first few warming days approaching early spring. This may kill the rhizome, or it may cause rotting or induce botrytis infections. We recommend right after the first frost in late fall, you thoroughly groom the iris bed (see grooming above), then follow up by trimming each iris into a fan of approximately 8" to 12" tall. Many growers cover their iris with 3 or 4 inches of coarse sand. They do this right after the first frost in late fall by carefully placing the coarse sand loosely over the rhizomes, then they remove it right at the first warm days of spring. Other growers prefer using bales of straw. Again, they do this right after the first frost in late fall by carefully placing straw 5 or 6 inches deep over the rhizomes, then they remove it right at the first warm days of spring. If you decide to use straw, please be careful not to mulch or pack down the straw, since it can retain too much moisture and rot your rhizomes. Never ever use vinyl, shredded paper, leaves, peat moss, or grass clippings since these will rot your iris. If you want to experiment with other materials, just be sure they are of a type of porous material that will allow air to get to the rhizomes.|
|ENJOYING IRIS INDOORS|
|An Iris flower arrangement will last a week or more indoors too. The key is to keep the flowers drinking. Iris flowers are living things and need to be fed and watered just like we do. Start by preparing the vase, select one that will be able to keep a stem upright and wet. Cut your flowers at the base of the stem where it leaves the plant, normally the stem will have 3 branches with several flowers and buds on them. A good pair of scissors or pruning shears will work just fine. Make your cuts at a 45 degree angle, this increases the surface area which improves water uptake. Place the stem in the vase you have selected and fill it with water. Don?t cram too many stems into a container that?s too small. The vase needs to hold enough water to last for a day or so, plus the stems need a little room to breathe. I recommend using lukewarm water, just like your giving the baby a bath, it will allow the flowers drink more quickly. The flower fresh stuff the florist uses really works too. It contains sugar to feed the flowers and chemicals to slow the growth of algae and bacteria. Bacteria not only makes the water smell, it clogs up the stem and reduces water uptake. To make your own, just mix a teaspoon of bleach and a tablespoon of sugar in a gallon of water. Some gardening experts say you can pour a 12-ounce can of non-diet Sprite or 7-Up into a half gallon of water, they say the acid in the soft drink will slow bacteria growth and the sugar will feed the plant. But whichever you choose, be sure to change the water every day, or every other day. Even using the freshener, bacteria will grow, and you want to get rid of it. When you change the water you should also cut the stems another inch or so. By the end of the week, you have a shorter bouquet, but it?s still a beautiful flower arrangement. When a flower withers, simply pinch it off at the base of the flower, but be careful not to disturb the other buds that may be there. Those unopened buds will also open to continue your flower arrangement several more days. Cut iris flowers last longer when they are cool. So like any flower it's best not to put them where it gets warm, like on a television set, near the stove, or in front of any window that gets direct sunlight. Also keep your flowers away from the fruit bowl, the fruit gives off ethylene gas that make the flowers deteriorate faster. If you were given pre-cut flowers that were not in water, you?ll need to act quickly by cutting off about an inch from the bottom of each stem, then get them into water as fast as possible following the above instructions.|
|Although most irises are tough and rarely succumb to disease, you should be aware of the following types of infestations.|
|Fungal Leaf Spot (rust)|
Leaf Spot is rarely seen in arid dry climates both warm and cold, like
Arizona and Colorado, but in the Coastal regions, Northwest, and Eastern seaboard,
it can be a continual problem.
After blooms appear, leaves
may become dotted with small brown spots with a watery streaked
fungus will not do significant harm to plants if it occurs in small
amounts, but if it gets out of hand and spreads to other plants, it can
weaken all of the leaves, thus eventually kill the plants. If fungus strikes,
remove all dead and diseased leaves, and spray with a fungicide containing CHLOROTHALONIL
(formerly Daconil), such as found in "Ortho Garden Disease Control".
Spray the infected parts of the plant. Usually you will need to spray four
(4) to six (6) times, within seven (7) to ten (10) days of each other, to
control this disease.
Fungal Leaf Spot runs a two year cycle, so if you had it last season,
you?ll have it this season. Start your spray program early, until the days
are warm and dry. The sun is nature?s cure, but if you live in an area
with rainy summers, the leaf spot can persist. Clean your garden
regularly, removing dried leaves and old bloom stalks, where spores can
over-winter. Keep aphids, thrips and whitefly in check, because they can
spread the spores. Spray in early morning so the morning sun dries the
foliage. Divide your plants every three or four years. The denser the
foliage, the worse the leaf spot. Allow good air circulation and always
If you want to use a non-chemical spray, the American Iris Society
recommends the following: To a gallon of water, add three (3) tablespoons
baking soda, two (2) tablespoons of shavings from a bar of Ivory soap, and
one (1) tablespoon vegetable oil. Apply the spray to infected parts of the
plant. This does prevent mildew, and may work on leaf spot as well.
Prevention is the best cure, so if you are in a moisture prone area, to avoid fungal leaf spot it is best to plant irises in full sun, in a rich well drained soil, also try to select disease resistant varieties, and do not water with overhead watering systems (I use a weeping soaker type garden hose system).
|The most threatening to iris
are iris borers. They will attack all kinds of irises. In the northeast especially, the eggs are laid in the
fall on leaves. The first sign of their presence is ragged notches on the
leaf edge dripping with sap, or small accumulations of sawdust-like frass
(borers excrement), and streaks and wandering tunnels
on your iris leaves that later turn yellow and brown. Iris that are
severely infested may also fail to bloom. Each spring, the borers larvae
begin to hatch after the first two days of temperatures greater than 70
degrees. New England gardeners have observed that hatch begins about the
same time their tulips bloom, and it continues into June.
The inch long larvae crawl up the
iris leaves. Near the top they chew into the leaves. Then they eat their
way down inside the leaves to the rhizomes, where they gorge themselves
until they reach a length of about 1 to 1 inches and are pink-gray in
color with dots on their sides and a brown head. Borers often will hollow
out whole rhizomes causing fans to collapse and the remaining tissue to
rot. Some time in the summer the borer larvae change into pupae with a
chestnut brown chrysalis or cocoon. These pupae reside in the soil for
about a month and then a moth emerges and lays eggs on
leaves, and the cycle starts over.
Borers in the pupae, moth and egg stages do not feed. Only
as a larvae do they eat and do damage. At this stage they are most
vulnerable to our efforts to control them. They
also can spin a tiny web and use it to hang-glide off to irises some
distance from where they hatched.
If iris borers strike, first remove all withered foliage and debris next
to and near your iris plants. This should be done in the spring as well as
late fall, as this is where the eggs will be. Do not compost the debris,
but dispose of it in the garbage. In the spring, when new growth starts,
spray the leaves with systemic insecticide containing ACEPHATE (formerly
Isotox) such as what is found in "Ortho Systemic Insect Killer".
To be on the safe side, spray a second time within seven (7) to ten (10)
days. You can do this up to bloom time. You should also feel the leaves,
if you sense a lump that might be a borer, squeeze it and kill it.
If the borer has chewed its way
further down the leaf, it may be easier to remove a portion of the leaf
than search for and destroy the borer.
If the problem is advanced, dig all the rhizomes after
bloom, usually July or August, and physically remove the borers by
squeezing them to death with gloved fingers.
|Bacterial Soft Rot|
|Although not as common as leaf
spot or iris borer infestation, bacterial soft rot can be a very serious
problem unless treated. What happens is bacteria enters the rhizome
through surface injuries or cuts, such as those that iris borers inflict,
or you accidentally may inflict on the rhizome when planting or weeding,
etc.. A yellow ooze soft rot sets in and causes the rhizome to become
mushy and smelly. To treat this you must dig up the rhizome, remove
all mushy leaves, and cut off all mushy tissue with a sharp knife.
Disinfect the knife after each cut in a solution of 10-20% bleach. After
the rhizome is free of all mushy tissue, soak it in the bleach solution
for several minutes. Rinse the rhizome, then place it in the sun or open
air to dry for 24 hours, then replant. If the rot is too extensive, the
rhizome must be discarded.
Bacterial soft rot is also caused by over-watering, poor drainage, mulching, over fertilizing, using fresh manure, and the use of high nitrogen fertilizer, prevention is the best cure.
|Crown Rot or Mustard Seed Fungus|
|The disease earned its nickname Southern Blight because of its prevalence in a geographical belt that runs from Tennessee to Texas, but it can be a problem in any climate, from Maine to Southern California. This disease is soil borne, and over 300 plants can be host carriers, from beets to wheat, the list is extensive. To control this fungus, trim all leaves to about six (6) to eight (8) inches to allow more sunlight and air circulation. Remove and destroy all leaves that show evidence of disease. You can recognize Mustard Seed Mold usually only after it has progressed to a reproductive stage, releasing ?fruiting bodies? or spore sacks that resemble Mustard Seeds with a reddish color. These will be found around the ?crown? or top of the rhizome, and around the soil particles near the plant. Eventually, the fan falls over and bacterial rot sets in, making it worse. Without the bacterial rot, the rhizome develops a chalky white look, flaking and cracking like a bad skin disease, and root systems will have a white or greyish webbing like spider-web or cotton strung through them. Treatment is to remove the plant and burn. But if the plant isn?t too far gone, a soak in TERRACHLOR (PCNB) will kill the fungus, and save the plant. Since Mustard Seed Mold is soil-borne, Terrachlor must be drenched into the ground where the fungus was found before replanting. The fungus can persist in the soil for four or five years, maybe longer, and when you replant iris there, it will infect them. Sterilization by composting or burning will, of course, eradicate the fungus, but composting may not reach adequate temperatures for total eradication, and burning may not go deep enough into the soil. For this disease, Terrachlor chemical control seems best.|
|Snails and Slugs|
|Snails and slugs are members of the mollusk group and are similar except slugs lack the external shell. They move by gliding along on a mucous-secreting muscle. The dried mucous becomes a silvery slime trail that tells you they have been dining in your garden. The common brown garden snail (Helix aspera) was brought to California as a culinary source from France in the 1850s. Moisture is critical to their survival and is why they are active only at night or during cloudy days. On sunny days they are hiding in moist, shady places. During hot, dry weather they seal themselves off with a membrane while attached to tree trunks, fences or walls. During cold weather, they hibernate in the topsoil. They are among the first pests to begin feeding in spring and the last to stop eating your iris plants in fall. The adult snail and slug each lay a mass of about 80-100 eggs and they may do this up to 6 times a year. The eggs resemble small pearls (about 1/8 inch); they can be seen about 1 inch below the soil level or under rocks, boards or plant debris and they hatch when they come in contact with moisture. It takes about 2 years for snails to mature but slugs mature in 1 year. The garden snail may live as long as 12 years but slugs only live about 2 years. Given all this, it is easy to see why there are huge numbers of these pests in the garden. Eliminating as many as possible requires persistence. Snails and slugs will damage your iris plants by chewing irregular holes with smooth edges in the leaves, as well as the bloom. It's best to physically remove all active insects when you see them. The best control is bait containing METALDEHYDE, such as what is found in "Corry's Slug and Snail Death". If you don't get rid of the snails and slugs, they will absolutely devour your Iris. We use the meal formula of Corry's Slug and Snail Death, not the pellets, and we buy it in the big twin-pack at Costco. You can sprinkle it directly on each plant, as well as around the plant in a circle, once a month in the wet months, then you should be able to cut back to once every few months during the dryer months. Corry's won't lose potency when it rains and it is super effective, but if you have these pests you will need to control them every year. If you have agapanthus (lily-of-the-Nile) near your Iris, it is important to note that these plants harbor snails and slugs, they don't eat them, they simply nest there just waiting to eat your Iris. So it's best to either treat them with Corry's, or better yet, remove them from your Iris growing areas altogether.|
|Populations of iris whiteflies have always been present in low numbers near strawberry fields in California. These species are usually kept below damaging levels by naturally occurring beneficial insects. Whiteflies go through six stages in their development: eggs; first, second, third, and fourth instar immatures; and the adult. Eggs are microscopic and laid on the underside of leaves. Whiteflies do not have a true pupal stage, but the last part of the fourth instar, when the red eyes of the adult whitefly begin to appear, is often referred to as the "pupa." Only adults and the newly hatched nymphs (i.e., crawlers) are mobile. In warm weather, whiteflies can complete a generation in as little as 18 days. Whiteflies are easy to distinguish from other insect pests: adults of all species are about 0.04 inch (1 mm) in size with four membranous wings that are coated with white powdery wax. Whitefly species are most reliably distinguished from each other by examining the late fourth instar or red-eyed "pupal" stage. Both adults and nymphs look similar but the Iris whitefly "pupae" lack long filaments but have short waxy ones around their bodies. Iris whitefly adults hold their wings flat over their backs and have a dot on each wing. Iris whitefly produce sticky honeydew that they excrete during feeding. The honeydew may cover plants and support the growth of black sooty mold fungus. Systemic insecticide containing ACEPHATE (formerly Isotox) such as what is found in "Ortho Systemic Insect Killer" is effective. Oils and soaps are also effective against adults and early instar whiteflies but not against eggs. Imidacloprid insecticide is not effective. Try to time treatments when most of the population is in the adult and first, second, or third instar stage. Good coverage of the underside of leaves is essential for effective use of insecticides against whiteflies.|
Gophers LOVE Iris rhizomes. If you see Iris plants that appear to have been "cut" maybe 5-6" below the buds, as though the stems were cut sharply with a knife, with the tops are lying on the ground uneaten or chewed on, you more that likely have an active gopher. You may also see a hole in the ground near a rhizome, or a hole with what appears to be a mound of tiny rock like pebbles of dirt. These are all signs of a gopher.
I use Electronic Gopher Repellent Units to keep my beds gopher free. There are battery operated units for around $20, and solar units for around $25. You should find them at Home Depot, or stores like that, and these units seem to work great. I prefer the solar units and have found they last for several seasons, and there is down time where the bed is unprotected if a battery needed replacement. These units are like a 12" spike in the ground, and they send out a high pitched noise every few minutes that tells nearby gophers that another gopher lives there. Gophers are very territorial and won't go where another one lives, instead they steer clear and go elsewhere. Depending on the size of your Iris bed, you may need more then one unit.
You can use the gopher poison that's available, but it's expensive and you'll find that you will be using it often. When you kill one gopher, you'll see another in a few months, this is because their tunnels go for miles.
If you don't rid your beds of gophers, they will eat all your prize rhizomes. First they come up and munch on the stems, then they retreat to eat the rhizome underground.
Russ & Nancy's Tall Bearded Iris Collection
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