There is no universal rule to apply in growing tall bearded irises. One must take into consideration the type of garden, the soil, the climate, and the incidence of disease in the area.
Planting Irises
Iris grows well if planted alone in rows or in a designed bed. When growing in a mixed bed, do not place it among other plants, but use it in the border where plants can receive maximum sun and special treatment.
Let the sun reach the rhizome. The minimum requirement is a half day of sun.
Good Drainage
Good drainage, the most important requisite, is more easily obtained in light, sandy soil. Therefore, before planting the iris, work the soil 10” to 12” inches deep, digging in humus and, if the soil is heavy, sand and compost.
Where water standing is dangerous, it is better to have the beds raised. A neutral or slightly acidic soil is desirable.
Fertilizing
Manures were formerly forbidden but are now generally used. Well-rotted manure may be worked into the soil if dug in deep enough to avoid contact with the rhizomes.
Where the soil is heavy and there is a great deal of rain, manure should be applied cautiously, as it increases root rot.
The most favored fertilizer is bone meal, so work in a handful for each rhizome before planting. Use it as a top dressing in late June on clumps that are not being reset and have not previously had it.
Superphosphate is good for the iris and may be used with the bonemeal. In the spring, a top dressing of the superphosphate, at about four ounces to a square yard, is recommended.
Dividing Clump of Iris Depends on Size
When to divide a clump of iris depends on its size. A clump should never grow so large that the rhizomes climb over each other.
For best results, divide every two or three years, though sometimes clumps may be left for four years. In the northern states, transplants soon after they flower, so the plants will be established before winter sets in.
Setting A Rhizome
In hot sections of the country, planting is done in late summer or early fall. In setting a rhizome, first, work a handful of bone meal or fertilizer deeply into the soil, then make a hole large enough to spread out the roots.
Place the bottom of the rhizome on a slight mound in the center of the hole with the roots spread out.
Pull the soil up around the rhizome, keeping the mound high enough so that the rhizome is not more than an inch below the surface.
In heavy soil, the rhizome can be exposed, but in light soil, it should be covered. The soil should be firmed around the rhizome with the feet, and when finished, the rhizome should be parallel to the surface.
Transplanting
Space new plants not closer than 15” inches if they are to stay for a few years.
The newer, more vigorous rhizomes on the outside should be used to transplant an old clump. Cut leaves back about six inches before resetting.
Circle Planting
All rhizomes should face in the same direction, away from the path or lawn. Circle planting has been suggested, but the rhizomes grow out with a bare space in the center. Therefore, new plantings should be kept well-watered until established.
In hot weather, shade newly set plants with shingles for a few days. Established plants require watering only in a dry summer.
Iris should not be mulched in the summer because they need the sun on the rhizomes. Instead, keep them free from weeds, leaves, and rubbish, and cultivate only the surface. Winter protection depends on the climate.
In the colder states, give protection to newly set plants. Winter covering may be marsh hay, straw, excelsior, or light covering. Fir boughs are often used, and pine needles, when plentiful.
Iris Diseases
Diseases of the iris vary in different sections of the country. Fortunately, new methods of combating them are being discovered.
Root rot of several types is most prevalent. One occurs in a hot, humid summer when the rhizome gets soft and gives off a foul odor.
Useful Aureomycin
Aureomycin has proved helpful for this trouble in the proportions of three tablespoonfuls to a gallon of water.
Another good treatment is to clean out the rot with an old tablespoon and pour on a solution of potassium permanganate, one level tablespoonful to a gallon of water.
Expose the rhizome to the sun and fill the cut with gypsum before replanting.
Iris Borer
Iris borer is prevalent in many places but can be controlled by a spray of six tablespoonfuls of 50% wettable DDT, with three tablespoonfuls of fermate and some spreader to three gallons of water.
Botrytis
Botrytis, a different type of rot, is caused by a fungus that attacks plants in the wet winter months.
A velvety gray mold appears at the base of the fan and the rhizome gets dry and corky. Captan is the best new remedy. Use in the late fall as a preventive and in the spring on plants that need it.
Another effective preventive for this and other ills is to soak the rhizomes in a solution of semesan a half hour before planting.
Leaf Spots
Leaf spot is an unsightly fungus that attacks iris leaves following a long wet spring but does no serious damage.
Label Your Plants
A prudent iris grower will see that the plants are well-labeled with legible information. Equally important are relatively indestructible labels.
Amazing changes have taken place in the iris. Hybridizers produce sturdier plants, with flowers of heavier substance that hold up against wind and weather. Stalks are better branched, which makes for longer flowering and a superior appearance.
But perhaps the most striking change is the improvement in solid colors and new colors and combinations.
A few years ago, a good pink iris was unknown, but now we have the superb Lynn Hall and Pink Fulfillment.
In contrast are the nightshades, such as Total Eclipse and Deep Black. Progress is being made toward the true reds in the such iris as Trim and Bang.
Wide ruffling and flares are present in luscious colors in First Violet and Violet Harmony. The pure blue of Eleanor’s Pride and the pure white of Flying Squadron far outdistance the colors of their ancestors.
Bazaar and Zulu Warrior are wide white plaques bordered in rose red. Dotted Swiss is a white dotted with blue.
Nashboro is one of the outstanding new variegates, while Gaylord and Cape Cod are excellent amoenas with white standards and blue falls.
Iris now has laced, and fringed edges, and one of the loveliest of these is Butterscotch Kiss.
44659 by Jeannette W. Nelson