perennial
Siberian iris 'Caesar's Brother'
Iris sibirica 'Caesar's Brother'
Preview: plant data is awaiting horticulturist review. A professional horticulturist hasn't reviewed our plant table yet. Lists still follow fixed rules for zone, sun, pets, deer and invasive status.
Siberian iris 'Caesar's Brother' is a perennial hardy in zones 3–8. Expect 2.5–3 ft of height and 1.5–2 ft of spread; our lists space it 1.5 ft apart. It does best in full sun to part sun with average water, and it copes with wet soil. Expect purple flowers in May to June. In a FloraVista list it usually plays the filler role: a flowering plant that fills the middle or front of the bed. Deer usually leave it alone, and it is toxic to dogs and cats. Our rules leave it out of lists in Florida and the Gulf and the Desert Southwest, where summer heat, humidity or mild winters hold it back even inside its zone range.
Facts from our plant table
- Botanical name
- Iris sibirica 'Caesar's Brother'
- Plant type
- Perennial, herbaceous
- Hardiness zones
- 3 to 8
- Sun
- Full sun (6+ hours); Part sun (4–6 hours)
- Water
- Medium; tolerates wet soil
- Soil
- Moist, slightly acidic soil; tolerates wet spots.
- Mature size
- 2.5–3 ft tall × 1.5–2 ft wide
- Spacing
- 1.5 ft apart (centre to centre)
- Growth rate
- Medium
- Bloom
- May–Jun · purple
- Roles in a bed
- Filler
- Styles
- classic, cottage, modern
- Deer resistance
- High: deer rarely eat it
- Pets
- Toxic to dogs and cats. ASPCA lists iris as toxic (rhizomes): vomiting, drooling.
- Native to
- Not native to the US (or a garden hybrid)
- Pot size and price
- 1-gallon pot, typically $12–$20 (easy to find)
- Plant in
- Spring or Fall
- First-year watering
- Water deeply once or twice a week through the first growing season; keep soil evenly moist, not soggy.
- Pruning
- Cut foliage down in late fall; divide when the centre dies out.
Sources: ASPCA Toxic and Non-Toxic Plant List (from general knowledge; not re-checked unless verification is web-checked); Missouri Botanical Garden Plant Finder and grower tags; State extension service guidance and USDA PLANTS distribution maps; Rutgers NJAES Landscape Plants Rated by Deer Resistance; Invasive Plant Atlas of the United States and state noxious weed lists; Typical 2026 US garden-centre and big-box retail listings (estimate). Not yet reviewed by a horticulturist.
Guides that include this plant
- Deer-resistant plants for a full-sun bed in zone 4 (as a substitute)
- What to plant in a full-sun bed in zone 4 (as a substitute)
- What to plant in a full-sun bed in zone 5
- What to plant in a full-sun bed in zone 6
- What to plant in a full-sun bed in zone 7 (as a substitute)
Good companions
The plants our list engine most often puts in the same bed as Siberian iris 'Caesar's Brother', across the sun, zone, pet, deer and style combinations it fits.
- Feather reed grass 'Karl Foerster'Calamagrostis × acutiflora 'Karl Foerster'ornamental grass · zones 4–9
- Lamb's ear 'Helen von Stein'Stachys byzantina 'Helen von Stein'perennial · zones 4–8
- Korean boxwood 'Wintergreen'Buxus sinica var. insularis 'Wintergreen'shrub · zones 4–9
- Dwarf fountain grass 'Hameln'Pennisetum alopecuroides 'Hameln'ornamental grass · zones 5–9
- Dwarf boxwood 'Green Gem'Buxus 'Green Gem'shrub · zones 4–8
- Dwarf Alberta spruce 'Conica'Picea glauca 'Conica'shrub · zones 3–7
If you can't find it
Substitutes our engine offers for Siberian iris 'Caesar's Brother': same role in the bed, passing the same rules.
- Garden peony 'Sarah Bernhardt'Paeonia lactiflora 'Sarah Bernhardt'zones 3–8 · flagged toxic to pets
- Shasta daisy 'Becky'Leucanthemum × superbum 'Becky'zones 4–9 · flagged toxic to pets
- Spike speedwell 'Royal Candles'Veronica spicata 'Royal Candles'zones 3–8 · not flagged toxic to pets
- Hardy geranium 'Rozanne'Geranium 'Gerwat' (Rozanne)zones 5–8 · flagged toxic to pets
How this page was made
This page was generated from this plant's record in FloraVista's plant table by fixed rules. The companions and substitutes come from the lists our rules engine composes. No named expert has reviewed this page.
Data status: the plant table is awaiting review by a horticulturist. Check each plant with a local nursery or extension office before you buy.
Sources
- Missouri Botanical Garden Plant Finder, state extension services and the USDA PLANTS database (zones, size, sun, water, bloom, native range)
- ASPCA toxic and non-toxic plant lists (dog and cat toxicity)
- Rutgers NJAES and regional extension deer-resistance ratings
- State noxious-weed and invasive-plant lists and the Invasive Plant Atlas of the US
- Typical US garden-centre listings (pot size and price band)
Generated . How FloraVista chooses plants