Iris Bulbs and Plants

In Switzerland you plant bulbous iris in autumn and bearded iris ideally in late summer. Irises are easy to care for, hardy and, depending on the species, flower from February to June.

Buy iris: the main types at a glance

The genus Iris includes several hundred species. For the garden, four groups are particularly important:

• Dutch iris (Iris hollandica): grows from bulbs, flowers in May and June on stems 50 to 70 cm tall and is a popular cut flower. A classic is the deep violet 'Discovery'; there are also varieties in blue, white, yellow and bronze.
• Dwarf iris (Iris reticulata): only 10 to 15 cm tall, flowers as early as February and March and suits rock gardens and bowls.
• Bearded iris (Iris germanica): a perennial with a thick rhizome and large, often fragrant flowers with a «beard» on the falls, 60 to 100 cm tall, flowering in May and June.
• Siberian iris (Iris sibirica) and Japanese iris (Iris ensata): slender perennials for moist to wet soils, for example at the edge of a pond.

Planting time and position in Switzerland

Plant bulbous iris (Dutch and dwarf iris) in autumn from September to November; on the Swiss Plateau even into November, as long as the ground is not frozen. Bearded iris is ideally planted in late summer from July to September so that the rhizomes root in before winter; container plants can also go in in spring. Almost all irises love full sun. Bearded iris needs free-draining, rather dry and preferably chalky soil, while Siberian and Japanese iris tolerate more moisture and partial shade.

Planting and care

• Plant Dutch iris about 8 to 10 cm deep and 8 to 10 cm apart, dwarf iris around 7 cm deep.
• Set bearded iris rhizomes shallowly so that the top remains visible. Spacing around 40 cm.
• Once established, water only during prolonged dry spells and always avoid waterlogging.
• Divide bearded iris every three to four years after flowering, when the clumps become bare in the middle.
• Most irises are hardy in Switzerland. In harsh areas, cover Dutch iris with a few leaves.

Irises contain irritant substances, especially in the rhizome and bulb, and are harmful to people and pets if eaten.

Combining and uses

Dutch iris look good in groups among late tulips, alliums and peonies. For the vase, cut the stems as soon as the bud shows colour. Bearded iris suits sunny perennial borders with salvia, hardy geraniums and poppies; dwarf iris pairs well with crocuses and squills.