Siberian iris

Questions about Siberian iris

Does Siberian iris need sun or shade?

Siberian iris grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).

It wants soil that stays evenly moist, of average fertility, and a good soak in dry spells. Once settled in, it stands drought.

What zones does Siberian iris grow in?

USDA zones 3 to 9. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).

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

When does Siberian iris flower in my zone?

In zone 5 it flowers late May to late 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 Siberian iris be planted?

18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.

It grows 2½ ft (75 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many Siberian iris plants do I need?

At 18 in apart, set out in staggered rows:

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

In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.

In the bed above, the planner used one in one group.

Is Siberian iris poisonous to dogs and cats?

Yes: mild toxicity to people, dogs, cats and horses. The underground stems (rhizomes) 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 Siberian iris?

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

• Peach-leaved bellflower: the same job in a bed and the same colour; 6 in narrower, flowers mid June to mid July.
• Meadow sage 'Caradonna': the same job in a bed; 6 in shorter, flowers late May to mid July.

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

Do deer eat Siberian iris?

Mostly not. NC State lists it as resistant to deer and rabbits. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.

What flowers after Siberian iris?

Siberian iris is over by late June. These start as it finishes and carry the same spot on, so it never goes flat:

• Daylily: from late June to early August, 2½ ft tall (a recorded partner).
• Black-eyed Susan: from mid July to mid September, 24 in tall.
• Butterfly weed: from late June to early August, 24 in tall.

What does Siberian iris look like in winter?

Siberian iris dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.

Is Siberian iris good for bees and butterflies?

Siberian iris is visited by pollinators, bees and butterflies.