Dutch iris, how to care for Iris hollandica

Got a flower bed or slope begging for blooms? Well, jackpot guaranteed with Dutch Iris!

Key Dutch Iris facts:

Name: Iris x hollandica
Family: Iridaceae
Type: bulbous

Height: 1 to 2½ ft (30-75 cm)
Exposure: sun, partial shade
Soil: rich, well-drained, dry in summer

Foliage : deciduous – Bloom: between April and July

Their delicate flowers come together to create a fabulous bloom in May and June. Picture it in your garden, in a planter, or even in a vase. Sounds good, huh?

Planting Dutch Iris

Plant your Iris X hollandica bulbs from September to October-November. Give them enough time to settle in before cold weather hits. For container growing, you can plant at any time of year.

Dutch Iris welcomes all light, well-drained soils, preferably limestone to slightly acidic. Summer drought in a sandy or rocky soil? Not a problem, they’ll just take a nap until things get better. But they truly despise heavy, waterlogged winter soil. Do them a favor and plant them in full sun, or maybe part shade.

Want to make the most of their graphic effect and often exceptional colors? Go for a mass effect by planting groups of at least 5 bulbs, spaced 4-6 inches apart (10-15 cm). But don’t go overboard with this iris, as its foliage quickly turns yellow in June, leaving the ground bare.

• Loosen soil thoroughly, adding sand, gravel, or potting soil if needed (5 shovelfuls of well-decomposed compost per square yard or meter) to improve drainage. You can even lay a gravel bed of about 1 inch (3 cm) just under the bulb.
• Place the bulb on its flat base, between 4 and 6 inches deep (10-15 cm). Planting that deep keeps greedy voles at bay!
• Cover with soil and water.
• Feel free to mark the location with a small sign or slender ornament.

→ More on planting bulbs: Bulb flower planting tips

Dutch Iris in a pot

Got a sunny balcony or courtyard? A wall in need of charm? You can grow Dutch Iris in a pot too! For pot or planter planting, stick with shorter varieties that are 16 to 20 inches tall (40 to 50 cm). Also does fine indoors.

• Pick a pot that’s both wide and deep enough to fit a party of 5 bulbs.
• Start with a drainage layer (clay pebbles or stones), then fill it up with a well-draining mix of sand, leaf compost, and peat.
• Plant your bulbs and give them a good watering.

Dutch iris care

Once settled in, Dutch iris more or less cares for itself. It’s a perennial that asks for little, it doesn’t put up a fuss if you forget about for a while.

• Weed in spring. Standing alone helps iris blooms to truly shine.
• Cut off faded flower stems, but leave foliage until it yellows. Pull out when dry to clean up your flower bed.
• Spring is when you should water – about once a week if the substrate dries more than 1 inch (3 cm) deep. Cease watering in summer, this is the bulb’s resting time. If needed, start watering again in fall but stop in winter. It’s not unusual for slender, linear leaves to reappear in fall. That’s your cue to water, especially if you’re growing them in pots.
• Bulbs planted deep are cold-hardy, cheerfully withstanding 5 to -4°F (-15 to -20°C).
• If blooms look less radiant, add potassium-rich fertilizer (beet molasses or ashes, for instance) in early spring and right after blooming. It helps replenish bulb reserves.
• After 4-5 years, if blooms are losing their charm, think about dividing bulbs.

→ Read more: Iris: a stunning perennial flower

Pests and diseases of Dutch iris

Not many pests attack Dutch iris. Rot is the most common issue in poorly drained soil. Improve drainage. Try planting on a mound or slope if needed.

Voles sometimes snack on bulbs. To avoid this, plant bulbs 6 inches (15 cm) deep. Slugs and snails may munch on leaves and flowers. Be vigilant and remove them in the evening.

Dutch iris propagation

Get the job done with clump division, in fall or spring.
This plant has a knack for naturalizing itself, spreading by producing bulblets.

• With a garden fork, lift the clump and separate bulblets from the main bulb.
• Replant them immediately, a bit farther away in well-prepared soil.

Learn more about Dutch iris

Iris x hollandica, also known under the name Iris of the xiphium group or Dutch iris, is the result of crosses between Iris xiphium (blue-purple bloom with sepals marked by a yellow spot) from the west of the Mediterranean, and I. tingitana from North Africa. This latter has gifted this progeny with the purity of its colors. These two bulbous iris have thus given birth to a multitude of cultivars with particularly sought-after pure shades for the cut flower.

A solitary or paired flower consists of 3 horizontal sepals marked by a yellow or orange spot and 3 raised petals. The corolla measures 3 to 4 inches in diameter (7 to 10 cm) and stays open for about a week before giving way to other flowers on the spike. The flowering thus stretches over 2-3 weeks depending on the cultivars.

Tones range from sky-blue ‘Wedgwood’, to deep purple ‘Professor Blaauw’ passing through the cobalt blue of ‘Blue Magic’ and many other white, purple, bronze, yellow, bi or tri-color hues. Dutch iris’s elegance and delicacy are characterized by:

• the slender lines of its stem,
• the curvature of its fluted foliage with medium to gray-green tones,
• its flowers with clear contours and vibrant colors. Yellow splashes sometimes ringed with white mark the 3 sepals of the flower, highlighting the depth of the colors. As such, they are part of the beardless iris group.
• These iris measure 16 to 32 inches tall (40 to 80 cm) and are just as good in the back of a flower bed, against a wall, on a slope, or in a planter.

Smart advice

A good pairing for Dutch iris is to intersperse a few Ixia corms in the planter. Position them 4 inches from the surface (10 cm). Pansy, rose, and peony also make good companions.

→ To go further:

• Iris: a superb perennial flower
• Bearded Iris, the garden iris
• Marsh iris: yellow and aquatic
• Iris reticulata, a dwarf iris with early flowering