With its sturdy, grass-like, evergreen foliage, African iris is an excellent flowering groundcover or accent plant for warm climates (if you live farther north, you can still grow it as an annual, or overwinter it indoors). Count on dainty, bright white flowers from spring through fall with only two-week rest periods in-between, which also earned the plant the name fortnight flower. Call on vigorously growing African iris to add color and texture to tough landscaping areas. This plant from South Africa stands up to heat, drought, and neglect.
African Iris Overview
Where to Plant African Iris
For the best bloom, plant African iris in a location where it gets at least six hours of full sun. The plant does not have any specific soil requirements other than good drainage and a pH that is slightly acidic.
You can use mass plantings of African iris to make entryways look inviting or disguise spots that have little appeal, such as along a foundation. African iris is also a dependable addition to any rock or woodland garden.
How and When to Plant African Iris
Plant African iris after all danger of spring frost has passed. Dig a furrow about two inches deep and 6 inches wide. Place the rhizomes with the roots down and fanned out in all directions. Cover the rhizomes with 1 inch of soil. Space them at least 1 foot apart. Water well after planting and keep them evenly moist until they are established and have grown a substantial amount of foliage.
African Iris Care Tips
Light
African iris blooms best when it gets full sun for six hours or more. Partial shade during the hot afternoon hours is only acceptable in hot climates with Western exposure.
Soil and Water
Loamy soil is ideal for African iris, but it grows it different types of soil as long as there is good drainage, and the pH is between 6.0 and 8.0.
Watering is usually only needed during the first growing season until the plant is established.
Temperature and Humidity
African iris is not winter-hardy below zone 8 so you’ll need to grow it as an annual or overwinter it inside as a potted plant. The climate in its native habitat being hot yet dry, the plant does not do well in high humidity.
Fertilizer
Despite its long bloom, African iris is not a heavy feeder. A light application of a balanced complete granular fertilizer once in the spring and again in midsummer is usually enough. For the amount to use, follow product label guidance.
Pruning
To encourage a continuous bloom, remove the seed pods as they begin to form but leave the flower stems on the plant. For a neater appearance, you can also remove any dead leaves but that’s optional.
Potting and Repotting African Iris
To grow African iris in a pot, use one that is 1.5 times larger than the nursery pot and wider than tall, as the plant spreads by rhizomes. Also, make sure it has large drainage holes. Fill it with well-draining potting mix and compost. Keep in mind that container plants require more frequent watering and fertilization than plants in the landscape.
Repot the plant in a larger container with fresh potting mix when the roots have filled the pot. You can also divide the plant and repot it in several containers.
Pests and Problems
Common pests of African iris include nematodes, aphids, and iris borers. The plant can also be affected by scales that coat the foliage.
Soil that is too wet or too alkaline for the plant manifests itself as yellow discoloration of the leaves.
How to Propagate African Iris
African iris is best propagated by division. Dividing the clumps not only makes new plants but it also addresses the issue of crowding and poor air circulation in older clumps. In a warm climate, this can be done in the spring or in the fall. Dig up the entire clump with a shovel. Shake off excess dirt and use a sharp spade to slice the rhizomes apart. Discard any blemished and diseased rhizomes. Plant the healthy ones in the landscape at the same depth as the original plant.
Types of African Iris
Dietes bicolor
This African iris species has fewer and larger leaves than Dietes iridoides. The flowers are light yellow with dark brown or violet blotches. Zone 8-11
Dietes ‘Lemon Drops’
This is a slow- to moderately-growing hybrid of Dietes iridoides and Dietes bicolor with yellow blotches on creamy flowers. Zone 8-11
Dietes bicolor ‘Variegata’
This cultivar has variegated green foliage with cream-colored stripes. The flowers are yellow with maroon blotches. Zone 8-11
Frequently Asked Questions
- How do you overwinter African iris?There are two methods for overwintering the plant. You can overwinter the rhizomes by digging them up before the first fall frost. Let them dry for about a week in a cool, dry place, then pack them in a cardboard box with peat moss and keep them in a cool, dark place for the winter. Or you can bring potted plants inside in the fall. Place them in a window with bright light but barely water them. Alternatively, you can also place the pots in a cool, dark place like a basement where they will go fully dormant. Either way, once spring arrives and there is no more danger of frost, plant the overwintered rhizomes or move the pots outside.
There are two methods for overwintering the plant. You can overwinter the rhizomes by digging them up before the first fall frost. Let them dry for about a week in a cool, dry place, then pack them in a cardboard box with peat moss and keep them in a cool, dark place for the winter. Or you can bring potted plants inside in the fall. Place them in a window with bright light but barely water them. Alternatively, you can also place the pots in a cool, dark place like a basement where they will go fully dormant. Either way, once spring arrives and there is no more danger of frost, plant the overwintered rhizomes or move the pots outside.
- Is African iris invasive?The plant has the tendency to self-seed but it is not considered invasive. You can control the reseeding by cutting off the spent flowers before they set seed.
The plant has the tendency to self-seed but it is not considered invasive. You can control the reseeding by cutting off the spent flowers before they set seed.