6 ways to welcome irises into your garden

Although the iris blooming season is short, especially in spring, the blossoms rival those of orchids in their exotic details. Here are some tips if you'd like to see them growing in your garden. [Image credit: iStock.com/Lusyaya]

When designing iris plantings, remember that they're most striking when massed; their blooms will look like a swarm of butterflies hovering over the garden.

• Although some irises grow from bulbs, the popular bearded iris – so called for the hairs on the down-turned petals – grows from thick, shallow rhizomes. When the plants are not in bloom, they provide sleek texture with their stiff, pointed leaves.
• If you're looking for a spring bloom of irises, dwarf varieties are the way to go. They mix easily with little daffodils and many types are slightly fragrant.

Bearded irises need sun and well-drained soil.

• Side-dress plants with a balanced, timed-release fertilizer in the spring.
• If drainage is questionable, plant rhizomes in a mound of soil amended with coarse sand.

The best time to plant new irises is in early summer, soon after the plants have bloomed.

• Planting season continues into the summer, for as long as the soil stays warm.

Healthy plants seldom need dividing more often than once every three years.

• Irises tend to skip a season of bloom after they have been divided, so it's usually best to postpone division as long as possible.

When dividing irises, keep only the healthy outer parts of the clump, with a fan of new growth attached.

• Let the cut rhizomes dry in the sun for several hours, then replant them about 30 to 45 centimetres (14 to 18 inches) apart.

The worst pest of bearded irises is the iris stem borer, which tunnels into new leaves and bores holes in the rhizomes.

• Dig up and destroy badly affected plantings.
• In areas where problems with this pest are severe, treat irises with a pesticide that contains imidacloprid, which doesn't kill earthworms or beneficial insects.

Keep plantings neat by cutting back leaves by about half their length in late summer so that they have an attractive fan shape.

There are many different iris varieties to choose from.

• Dutch irises grow to about 50 centimetres (20 inches) tall and bloom in late spring. Dutch irises make better cut flowers than other types.
• Siberian irises offer a good change. Stiffly upright with purple, white or bicolour blossoms, a clump of these hardy irises makes a great vertical accent in a mixed perennial border.
• Louisiana irises are hybrids that are great for the edge of a water garden. There are numerous other irises that grow in shallow water.
• As mentioned, dwarf irises bloom in spring, mix readily with other spring-blooming flowers and often have a light fragrance.