Dutch iris

Questions about Dutch iris

Does Dutch iris need sun or shade?

Dutch iris grows in full sun (6 or more hours of direct sun a day).

It wants ordinary well-drained soil, of average fertility, and little watering once settled.

What zones does Dutch iris grow in?

USDA zones 6 to 9. It is hardy to zone 6, which means it survives winter nights down to about 0 °F (−18 °C).

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does Dutch iris flower in my zone?

In zone 5 it flowers mid May to early June. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should Dutch iris be planted?

4 in (10 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 5 in (12 cm), so a group knits into one patch.

It grows 22 in (55 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many Dutch iris plants do I need?

At 4 in apart, set out in staggered rows:

• 107 to fill 10 square feet (about 1 m²)
• 31 for a single row 10 ft (3 m) long
• 343 to fill a 4 × 8 ft bed on its own

In a mixed border, plant it as handfuls of five or seven, in the gaps between other plants.

In the bed above, the planner used 12 in two groups.

Is Dutch iris poisonous to dogs and cats?

Yes: mild toxicity to people, dogs, cats and horses. The bulbs and leaves can cause drooling and stomach upset if eaten.

Rated from NC State Extension and the ASPCA. Where references disagree, the more cautious rating is used.

Is there a pet-safe plant like Dutch iris?

These come closest to doing what Dutch iris does, and no toxicity is recorded for them:

• Triteleia 'Queen Fabiola': the same job in a bed, the same size and the same colour; flowers mid June to early July, wants dry soil.
• Grape hyacinth: the same job in a bed and the same colour; belongs at the front, not in the middle, 16 in shorter.

Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.

Do deer eat Dutch iris?

They may. NC State does not list it as resistant to deer or rabbits. Where they visit, protect it, or plant it among ones they avoid.

What can I plant to hide Dutch iris's leaves after it flowers?

A bulb's leaves have to be left to yellow for about six weeks after flowering, to feed next year's flowers. Plant it among perennials that come up late and spread wide, and they grow over the leaves as they fade:

• Catmint 'Walker's Low': 24 in tall and 2½ ft wide, a recorded partner, in flower mid May to mid September.
• Peony: 3 ft tall and 3 ft wide, a recorded partner, in flower late May to late June.
• Garden chrysanthemum: 24 in tall and 24 in wide, in flower mid September to late October.

What does Dutch iris look like in winter?

Dutch iris is underground: it dies back after flowering and waits as a bulb until spring. Mark where it is, so a fork does not find it first.