Iris Time
It’s time for tips on growing Louisiana Irises. Our state has several native iris species but only five are grouped horticulturally as “Louisiana irises.” Iris brevicaulis (Zigzag), Iris fulva (Copper), Iris giganticaerulea (Giant blue), Iris hexagona (Dixie), and Iris nelsonii (Abbeville red/yellow). The many colorful cultivars we know today are the result of these species that are closely related and have interbred only with each other. Louisiana irises are dormant in August and September and begin growing October through the end of May. Rhizomes can be planted in November.
Growing Tips
• Locate away from large trees or plants with extensive root systems.
• Blooming occurs March through May with optimal blooms occurring in areas receiving six or more hours of sun with afternoon shade.
• Place near water sources to maintain damp conditions if September-April rainfall is inadequate. Water weekly during dry spells.
Raised or Ground-Level Beds
• Remove unwanted vegetation and turn soil by a depth of eight inches. Amend sandy soils with four inches of organic matter. Improve clay soil by adding two to four inches of organic matter.
• Place rhizomes one to two inches below soil level and 12-18 inches apart.
• Mulch two to four inches deep. Pine straw is best for air flow, sun shade, feeding the soil, and permeability during rain/watering.
• Fertilize lightly in February with no nitrogen such as a 0-20-20 ratio. Use an all-purpose fertilizer such as Osmocote, 8-8-8 or 13-13-13 in October.
Aquatic Locations
• Use an 18-inch diameter by minimum eight inches deep container filled with soil.
• Place the rhizome just below the soil surface with at least four inches of foliage extended above the water surface.
• Water keeps rhizomes hydrated and protected from the sun. No mulch necessary.
• Fertilize with aquatic tablets placed under the pot during growing periods.
Irises are a symbol of faith, hope and wisdom. Sometimes they are given to those who may need uplifting and support. Consider Louisiana irises now for spring color. Happy Gardening!
For more fall gardening tips, visit lsuagcenter.com and see Sophisticated Woman’s October gardening article here.
