CULTIVATION OF BEARDED IRISES
BY DEE STEWART
When you receive your order
Unpack the iris immediately upon receipt. Ideally the irises should be planted within a day or so after receiving them. If not planted immediately, store in a COOL, DRY, WELL VENTILATED area for up to a week. The sooner the irises are planted (particularly the smaller "medians"), the more likely they will perform well the following spring.
What do I receive when I buy an iris?
You purchase the rhizomes. The rhizomes will vary in size greatly based on genetics and culture. Some TB rhizomes can be large while others will be somewhat smaller. Dwarf iris will be very small
When and where to Plant
For best results, iris should be planted in July, August or September, in a spot where they will receive at least half a day of sun; with EXCELLENT drainage. It's imperative that the roots of newly planted Iris be well-established before the growing season ends. In areas with hot summers and mild winters, September or October planting may be preferred.
Iris will thrive in most well-drained garden soils. Planting on a slope or in raised beds helps ensure good drainage. If your soil is heavy, coarse sand or humus may be added to improve drainage.
Depth to Plant
Iris should be planted so the tops of the rhizomes are exposed and the roots are spread out facing downward in the soil. In very light soils or in extremely hot climates, covering the rhizome with 1 inch of soil may be desirable.
Iris are generally planted 12 to 24 inches apart. Close planting gives an immediate effect, but closely planted Iris will need to be thinned often. Plants spaced further apart will need less frequent thinning.
Newly set plants need moisture to help their root systems become established. Specific watering information depends on your climate and your soil, but keep in mind that deep watering at long intervals is better than more frequent shallow waterings. Once established, Iris normally doesn’t need to be watered except in arid areas.
General Garden Care
Keep your iris beds clean and free of weeds and debris. Bloom stems should be cut off/or snapped off close to the ground after blooming. Remove any diseased or brown leaves.
What kind of Fertilizer is used?
Use either a balanced fertilizer such as a 5-10-10 or 6-12-12. Do not use any fertilizer with a high Nitrogen number as this will force rapid growth and lead to soft rot. I try to find a fertilizer low in Nitrogen which is the first of the numbers.
When to fertilize?
I fertilize two times a year. The first time, earliest spring just as the iris is starting to grow. The second time is at the very end of the season, or after I have finished planting the beds for the year.
What Diseases do Iris Get?
Relatively few, but there are some.
SOFT ROT: Bacterial soft rot is easy to identify by the soft, mushy, foul-smelling rhizome. Caused by over watering or over fertilizing or a combination of both. Yellowing of the leaves is usually the first indication of the problem, showing up at the bases of the fan. Scrape soil away from the rhizome. Use a spoon to scoop out the soft mushy tissue. Dust with a bleach based cleanser such as Comet or drench with a bleach solution of 1 part bleach to 9 parts water. Allow the treated part to be exposed to the sun for several days to dry out before covering with soil.
IRIS BORER: We do not have borers here in the West, so contact your local nursery.
FUNGAL LEAF SPOT: Can make the garden look unsightly and is caused by wet conditions. Spores that cause leaf spot can live in garden debris, so it is necessary to keep a CLEAN garden. Remove all the dead iris leaves. Wet winters keep an eye out for the beginnings of leaf spot. Cut off and destroy any leaf or part of leaf that is affected. Spray with Diainol, Captan, Benlate, Dithane, Maneb or Zineb in early SPRING and after each rain.