The planting time for iris bulbs varies with climate and variety. Most bulbs in U.S. Department of Agriculture zones eight through 10 should be planted when nightly temperatures are 40 to 50 degrees Fahrenheit or above. This is generally from July through October. Warmer climates may allow bulb plantings to be done even later.Continue Reading
When planting an iris bulb, it should be planted so the feeder roots grow downward into the soil. Requiring direct sunlight and room to spread, iris bulbs need to be planted 1 to 2 feet apart in shallow holes. Organic mulch should be applied to protect the tender root system, and regular watering is needed. Fertilizer should be applied to the ground above the roots, with care taken so the fertilizer doesn't directly contact the bulbs. Bulbs can be collected from mature plants by cutting back the leaves to about one-third of their length when the blooms fade. Older bulbs should be discarded, as only the younger ones flower again.
Irises are six-petaled flowers. Bearded irises have three upright petals and three hanging ones. Unbearded varieties have symmetrically falling petals. Both varieties flower in the spring, with beardless varieties continuing to bloom after the bearded varieties fade.Learn more about Outdoor Plants & Flowers