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Iris      

	Bearded Iris has filaments of hairs on the falls.
	Beardless Iris does not have filaments of hairs on the falls.
	Bulbous Iris has a bulbous root rather than a rhizome.
	Crested Iris falls have a central ridge or crest.

Light	Iris requires full sun.
Soil	Bearded Iris prefers fertile, well-drained, light soil Siberian Iris have a preference to fertile, moist-to-wet soil.
Planting	Prepare the garden by removing existing vegetation. Till the soil 10” deep. For new gardens, till in organic matter such as peat moss or manure. Dig a hole large enough to fit the root ball at the same depth as planted in the container. Place rhizome so that it sits barely under the soil, firming the soil around it. Iris rhizomes should be planted in August.
Mulch	Mulch should be used sparingly around bearded iris during the growing season. Apply Preen in the spring to help control weeds.
Watering	After planting, water well. Once established, Iris generally require an average 1” of moisture per week.
Fertilizer	Fertilize with a granular fertilizer such as Bachman’s 10–20–10 each spring.
Grooming	Remove spent flowers. Weed regularly; Iris don't do well when crowded with weeds.
Additional Care	Healthy Iris plants should be divided every 3-4 years in early August.   1. Dig the plants with a spading fork and gently pull apart the divisions.   2. Cut back the foliage to about six inches.   3. Replant. Large heavy blooms will likely require staking.
Winter Care	Prune foliage to about 6 inches after a killing frost. Mulch with straw or chopped leaves 4–6” inches deep after several hard frosts, when the ground is frozen. Uncover in early spring once the ground begins to thaw.

Problem	Cause(s)	Solution(s)
Lack of Blooms	Usually due to lack of sun. Planting too deeply.	Replant in August to a sunnier location. Rhizomes should be planted just below the soil surface.
Mice	Nest in the foliage over the winter.	Remove foliage after a killing frost.
Iris Borer	The larva attacks the central leaf stalk and tunnel downward into the rhizome.	Although iris borer may infest all types of Iris, Siberian Irises are more tolerant to attack. Check Iris during spring for evidence of chewing damage and water-soaked streaks. If an Iris plant has aboveground symptoms (brown leaf tips, deterioration), dig it up and examine the rhizomes. Discard rhizomes containing iris borer caterpillars and those with tunnels. A well-timed insecticide application can help reduce an infestation when new growth is 4-6” high; refer to the U of M extension service for recommendations.
Iris Leaf Spot	Leaf spotting is more common during wet seasons. Moisture on leaves and high humidity present favorable conditions for fungal infection.	Remove and destroy spotted or dead plant material, especially in the fall, to reduce the number of spores available for infection the following spring. Improve air circulation by thinning surrounding plants.

Related Bachman's Information

	Dividing Perennials
	Hardy Garden Lilies
	Peonies
	Perennials

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Select source information provided by the University of Minnesota Extension, www.extension.umn.edu.

Last Updated: April 2012