Dutch iris (Iris × hollandica) is a hybrid type of bulbous iris. The common name does not refer to its native origin but rather to the fact that it was the Dutch who hybridized it. Iris xiphium, the parent most associated with Dutch iris, is actually native to Spain and Portugal.
The flowers, which are typically three to four inches wide, are usually multi-colored. Blue, bluish-purple, white, and yellow are the most common predominant colors.
Dutch iris is not grown for fragrance, but it does make for a good cut flower. In fact, you may know it from floral arrangements that you have given or received, especially around Easter time.
Although this is a short-lived plant, it is easy to grow and, with the right sunny and well-drained conditions, it can naturalize in your garden, giving you a new set of flowers every year.
Dutch iris plants look their best when they are massed together in the landscape. For example, they work well in flower borders in sunny areas. Install them along a walkway or in a foundation planting, or they may also be grown in containers.
|Botanical Name||Iris × hollandica|
|Common Name||Dutch iris, Dutch hybrid group, fleur de lis|
|Mature Size||1.5 to 2.0 feet tall, with a spread of .25 to .50 feet|
|Sun Exposure||Full sun|
|Soil Type||Well-drained, with average moisture and fertility|
|Soil pH||Mildly acidic, neutral, mildly alkaline|
|Bloom Time||May to June|
|Flower Color||Most commonly blue, bluish-purple, white, yellow|
|Hardiness Zones||6 to 9, USA|
|Native Area||Hybrid (parent, Iris xiphium, native to Europe)|
|Toxicity||Non-toxic, but avoid ingesting|
Dutch Iris Care
Do not think that the growing season ends when the blooms are gone. It is only when the attractive, narrow leaves of the plant turn yellow that the growing season is over. While they are still green, the leaves should not be removed as photosynthesis is sending nutrients down to the bulbs during this time.
Dutch iris tolerates a bit of shade in the afternoon, especially at the warmer end of its hardiness range. However, in most cases, the plant will live longer and flower better if given full sun.
Provide Dutch iris with a light soil by mixing in generous amounts of organic matter.
The Dutch iris needs an average amount of water during its growing season and none during its dormant season. In fact, if your soil lacks ideal drainage and the bulbs are sitting in too much water during the dormant season, they may rot. It is largely because many gardens lack ideal drainage that the plants are often short-lived.
Work a 5-10-10 fertilizer into the soil two to three weeks before planting your Dutch iris bulbs in the autumn.
Dutch Iris Varieties
There are cultivars of the Dutch iris sold to cater to the demands of the gardening community for specific colors. For example, the names of the following cultivars indicate the predominant flower color for each plant in question:
- Iris x hollandica 'Blue Magic'
- Iris x hollandica 'White Excelsior'
- Iris x hollandica 'Yellow Queen'
Propagating Dutch Irises
The bulbs may produce offsets and spread over time, but these offsets usually do not mature for several years. In fact, Dutch iris tends to be short-lived. But the bulbs can be dug up and divided after the flowers have faded. Such division can invigorate your bulb patch. Alternatively, treat Dutch iris as an annual and simply plant additional bulbs each fall.
Growing Dutch Irises From Bulbs
Plant the bulbs three to five inches deep and also three to five inches apart; since the Dutch iris is a spring-flowering bulb, its planting time is fall.
Because Dutch iris is known to be short-lived, gardeners do not usually worry much about the pest and disease problems to which it can succumb. But examples of such problems include leaf spot, mosaic virus, root rot and iris borers.
Happily, the Dutch iris is not often bothered by deer or rabbit pests. Unlike many plants, it is also tolerant of the organic compound put out by black walnut trees (Juglans nigra) known as "juglone." This compound has what is termed an "allelopathic" effect on many plants. This can prevent them from growing, or, at least, prevent them from growing to their typical mature size.