Three horizontal sepals, each flashing a yellow spot, spread beneath three raised petals on a slender stem barely thicker than the grey-green leaves. Dutch iris (Iris x hollandica) is a bulb grown above all for cutting, in blues, whites, bronzes and yellows; give it light soil that dries out in summer and it will flower for weeks.
| 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 | mid-spring to midsummer |
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?
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.
→ More on planting bulbs: Bulb flower planting tips
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.
Dutch iris asks for very little, but the little it asks comes at set moments: planting, watering, and a summer rest. Here is the whole cycle in one view.
| Period | What to do | Why |
|---|---|---|
| Early to late autumn | Plant bulbs 4 to 6 inches (10-15 cm) deep, in groups of at least 5 | Bulbs need time to root before the cold, and depth keeps voles away |
| Early spring | Weed around the clumps and add potassium-rich fertiliser if blooms were dull | Clear ground shows the flowers off and feeding replenishes bulb reserves |
| Spring | Water about once a week | Only if the substrate dries more than 1 inch (3 cm) deep |
| Mid-spring to midsummer | Flowering: cut faded stems, leave the leaves | Foliage feeds the bulb until it yellows and pulls away dry |
| Summer | Stop watering altogether | This is the bulb’s resting time, and drought does no harm |
| Autumn | Start watering again if slender leaves reappear, especially in pots | New leaves are the cue that the bulb is active again |
| Autumn or spring, every 4 to 5 years | Lift the clump and separate the bulblets | Divide once foliage has yellowed, when the bulb is fully dormant |
Stop watering in winter and the bulbs will look after themselves until spring.
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.
→ Read more: Iris: a stunning perennial flower
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.
Get the job done with clump division, in fall or spring.
This plant has a knack for naturalizing itself, spreading by producing bulblets.
Lift the clump only once the foliage has yellowed and pulls away easily, as the bulb is then fully dormant and least likely to be damaged.
Discard any bulb that feels soft, hollow or smells sour.
Grow the tiniest bulblets on in a nursery corner or spare pot, because they need a couple of growing cycles to bulk up before they flower.
Seed from Dutch iris is not worth saving for colour, since these hybrids give variable seedlings that take years to bloom.
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:
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:
Cut Dutch iris for the vase when the bud just shows its colour, as it will open fully indoors.
The bulbs are toxic if eaten, so plant them away from spots where pets dig.
