Despite the tall, beautiful iris’ divine origins, it is rugged, reliable, and easy to grow. Learn all about planting, growing, and caring for this flower.
There are more than 250 species of plants in the Iris genus. The most well-known irises are the tall bearded irises, which can grow to be 2 to 3 feet tall. Their flowers have six petals, three of which hang down (known as “falls”), and three of which stand upright (known as “standards”).
There are two types of irises – bearded and crested (or “beardless”). Bearded irises have soft hairs along the center of their falls, while crested irises have a comb or ridge of hairs.
Irises typically bloom from late spring to early summer, with some varieties (primarily bearded hybrids) flowering a second time later in the summer. Siberian irises usually bloom around the same time as the bearded types.
Managing Pests and Disease
Although they are deer resistant and drought tolerant, irises are not immune to pests, bacterial infections, and fungal infections.
Aphids are small insects that can be either green or gray. They suck sap from leaves and spread disease from plant to plant.
You can remove aphids from your plants by spraying them with water from a garden hose.
The caterpillars of the Macronoctua onusta moth bore into the rhizomes of the tall bearded varieties of I. germanica.
You should check rhizomes regularly for small holes or water-soaked leaves. Any plants that are infested should be removed and discarded.
Caterpillars typically cause little damage to foliage, but can be controlled by handpicking them.
Snails and slugs are also known to eat leaves and flowers, creating irregular holes.
Pick the pests by hand and get rid of them. Remove anything nearby that they could hide in, like boards, bricks, and garden debris.
A barrier made of diatomaceous earth can also keep them from getting to plants.
Food grade diatomaceous earth is available at Arbico Organics.
If the seed pods of I. versicolor and purple Siberians, I. siberica have multiple small holes, remove them to prevent weevils from breeding.
The bacteria Erwinia carotovora causes soft rot, which can be a problem for bearded iris, I. germanica. The most likely time for it to occur is during warm, wet springs. Symptoms include soft, smelly rhizomes, decay at the base of leaves, and fan wilting.
If soft rot appears, remove the affected areas with a spoon and let the sun dry the remaining tissue.
After the wound has been sun-dried for several hours, sprinkle it with garden sulfur.
Bonide Sulfur Plant Fungicide is available at Arbico Organics.
Fungal crown rot, caused by Sclerotium rolfsii, is a decay that spread in the form of a soft, gray mat. It often appears in warm, moist conditions and covers rhizomes and the base of leaf fans.
To avoid crown rot, keep your garden tidy, use new and clean tools when handling rhizomes, and get rid of any infected plants immediately.
To prevent crown rot, which can be a regular problem, dip the rhizomes in a solution of bleach and water before planting. The solution should be a 10:90 ratio of bleach to water.
The infection known as leaf spot is caused by the Cladosporium iridis fungus, and is most common on the I. germanica plant. It appears as brown spots on the leaves that were originally water-soaked, and in wet weather, these spots may be covered in a soot-like substance made up of spores.
Any plant parts that are infected with leaf spot should be removed and disposed of.
Rust shows up as yellow spots that turn rusty brown, which then turn black. This causes the leaves to yellow and wither from the tip down.
If there are any leaves with rust on them, remove them and throw them away in the trash. This will stop the rust from spreading.
Irises are a diverse group of flowers that come in many colors, shapes, and sizes. They can be planted in many different areas of the garden.
Make sure to plant some flowers next to pathways and patios, so you can enjoy their fragrance and watch the butterflies and hummingbirds they attract.
Intermediate and taller varieties of plants are great for adding some pizzazz to mixed perennial beds, foundation plantings, cottage gardens, courtyard gardens, and cutting gardens.
Dwarf and intermediate-sized varieties of this plant do well when grown in containers or pots on patios, and all sizes—dwarf, intermediate, and tall—look great as part of a border planting.
Crested varieties of Iris, such as I. crestata, do well in light shade gardens because they can get by with less full sun than most other varieties.