Discover types of iris that grow from bulbs.
Fill your garden with the jewel tone blooms of iris bulbs. The irises that fall into the bulb group include a host of beautiful bloomers, some of which make perfect additions to cutting gardens. Others are dwarf beauties that act as true spring harbingers, often flowering through late spring snows in cold regions. Iris bulbs flower at some point from early spring to early summer, depending on type.
Iris bulbs share several traits in common with other spring bulbs. First, they’re usually planted in fall in most regions. The exceptions are early spring planting in regions where the iris bulbs aren’t hardy enough to survive winter. For instance, Dutch iris bulbs are hardy in Zones 5 to 9. In these zones, fall planting works well. But in colder regions, like Zones 3 to 4, spring planting is necessary because bulbs won’t survive winter.
Second, iris bulbs prefer well-drained soil. This is especially important during the bulb’s dormant periods. Third, the leaves eventually turn yellow after flowering. Just like with daffodils or hyacinths, it’s best to let iris bulb leaves age naturally to build food reserves in the bulbs for future blooming.
Dutch iris are probably the better known type of iris bulb. These are the iris often sold by florists and frequently referred to as florist iris. Dutch iris are hybrids of several different iris, including Spanish iris (Iris xiphium). You’ll see Dutch iris sold by the botanical name Iris hollandica and Iris x hollandica.
The flowers of Dutch iris open in a wide variety of hues. The purple and blue iris varieties are probably the best known. Dutch iris are beardless flower types, meaning the blossoms lack the fuzzy line found on bearded iris. Instead of the beard, there’s often what’s known in botanical circles as a yellow flame in that location on the petal. Purple petals with a yellow flame are a common type of Dutch iris. Yellow, burgundy and white iris blooms are also available among Dutch iris hybrids.
Many gardeners raise Dutch iris bulbs as part of their cutting garden. Each flower stem on a Dutch iris plant offers more than one bloom. The individual blossoms last three to five days each, but since one or rarely two subsequent flowers open on a stem, the vase life for these iris bulbs stretches to about a week.
Dwarf iris types also grow from bulbs. Reticulated iris (Iris reticulata) grows 3 to 6 inches tall and roughly 3 inches wide. Leaves are narrow and pointed and the flowers are miniature versions of purple iris blooms with gold flames. Reticulated iris is hardy in Zones 5 to 9, and blooms appear while late spring snows are still swirling in northern regions.
Iris danfordiae is also hardy in Zones 5 to 9 and grows to a diminutive size of 3 to 6 inches tall. Blooms are bright yellow and appear early in spring, a cheery addition to any rock garden or small entry garden. Like reticulated iris, Iris danfordiae is a type of iris bulb. Plant in fall for flowers the next spring.