How to Grow Dutch Irises

Dutch iris (Iris × hollandica) is a hybrid bulbous iris. Its name does not reflect its place of origin but rather the Dutch people who hybridized it. Iris xiphium, the parent species associated with the Dutch iris comes from Spain and Portugal. The 3- to 4-inch flowers are usually multi-colored. Blue, bluish-purple, white, bronze, rose, gold, and yellow are the most common colors.

Dutch iris is lightly fragrant and makes a good cut flower. It is commonly used in floral arrangements around Easter time. The Dutch iris is a spring-flowering bulb; its planting time is fall. It is a slow-growing, short-lived, easy-to-grow plant that can naturalize in your garden, giving you a new set of flowers every year, if it has ample sun and well-drained soil. Over many years, it may slowly spread itself. Dutch iris plants look their best when they are massed together. They work well in sunny flower borders. Plant them along a walkway or in a foundation planting. They can also be grown in containers. Dutch iris is often ignored by deer or rabbit pests.

Dutch Iris Care

Plant the bulbs pointy side up 3- to 5-inches deep and 3- to 5-inches apart. An irises' growing season continues past when the blooms are gone. Photosynthesis is sending nutrients down to the bulbs. It is susceptible to leaf spot, mosaic virus, root rot, and iris borers. But since it has such a short bloom cycle, it's not too much of a problem. Dutch irises seems to be immune to the juglone organic compound that black walnut trees (Juglans nigra) release in the soil that can kill or affect the growth of a lot of other types of plants.

Light

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.

Soil

Provide Dutch iris with a light soil by mixing in generous amounts of organic matter. Sandy loam soil is ideal.

Water

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.

Temperature and Humidity

Dutch irises are hardy in zones 5 through 8, meaning they can tolerate temps down to -15 degrees Fahrenheit. Irises love moisture, so humidity is a welcome condition. Irises can tolerate the heat and humidity in Florida and Texas.

Fertilizer

Feed the plants with a 5-10-5 fertilizer three times per year: at fall planting to feed the roots; when bulbs sprout in spring to nourish the foliage and flowers; and when foliages dies back to help feed the bulbs.

Dutch Iris Varieties

• 'Blue Magic' (Iris x hollandica): Features showy dark violet flowers with bright yellow markings
• 'White Excelsior' (Iris x hollandica): Compact classic white with a flaming yellow stripe
• 'Yellow Queen' (Iris x hollandica): Pure yellow iris with a strong stem
• 'Apollo' (Iris x hollandica): White flowers with a slight blue tint with yellow markings

Pruning

When the attractive, narrow leaves of the plant turn yellow, that indicates that the growing season is over. After blooming is finished, cut flower stems down at their base to discourage rot. While the leaves are still green, do not cut them yet. Only cut-off brown or yellow tips.

Propagating Dutch Irises

The bulbs may produce offsets and spread over time, but these offsets usually do not mature for several years. Plant iris bulbs in a site where the soil will be hot and dry during the summer months for the best chance of naturalizing. In areas with wet summers, dig bulbs after leaves yellow and store the bulbs in a dark, cool place to replant in the fall. You can also treat Dutch iris as an annual and plant additional bulbs each fall.

Potting and Repotting Dutch Irises

Use good quality, well-drained soil. Almost any commercially available potting medium will work fine. Dutch irises are prone to root and stem rot if they sit in soggy soil. Irises do better when planted in groups in large containers, so get containers that are at least 8 inches in diameter for four to five bulbs. You can fit about eight to nine bulbs in a 15-inch container. Position them about 3 inches apart.

Overwintering

Irises go into dormancy in the fall. They can tolerate snowy winters, but if you're in an area that gets consistent bitter cold snaps, give the plant a mulch covering up to 2 inches. If you live in a place that is wet over winter, you can dig up the iris rhizome (rootstalk) and store it in a dry, cool location. Brush off the dirt, powder with an antifungal or sulfur, wrap in newspaper, and store in a box. Check the box periodically for mold or rot. Toss those that get soft or begin decomposing.