Types of irises: bearded, Siberian, Japanese, Louisiana

I grow Siberian iris in my zone 7a Long Island garden -- a reliable, trouble-free perennial that comes back every year without much attention. It's not the most dramatic iris type, but it doesn't require the precise planting depth that bearded irises demand, it tolerates my occasionally damp soil,.

I grow Siberian iris in my zone 7a Long Island garden — a reliable, trouble-free perennial that comes back every year without much attention. It's not the most dramatic iris type, but it doesn't require the precise planting depth that bearded irises demand, it tolerates my occasionally damp soil, and the deer don't touch it.

The iris genus (Iris) is enormous — over 300 species — and the garden types divide into four main groups with substantially different cultural needs. Getting these groups confused is the most common reason irises fail in home gardens.

Bearded irises (Iris × germanica hybrids)

Per Missouri Botanical Garden, bearded irises are the most widely grown iris type in American gardens. They produce the large, ruffled flowers with distinctive "beards" (fuzzy caterpillar-like structures on the falls — the downward-hanging petals).

Key characteristics:

• Zones: 3–9 depending on cultivar
• Bloom time: May–June; some reblooming cultivars bloom in fall
• Soil: Well-drained, neutral to slightly alkaline (pH 6.5–7.5)
• Planting depth: Rhizomes planted half-exposed at the soil surface — the top of the rhizome should be visible or barely covered
• Sun: Full sun essential — 6+ hours minimum
• Moisture: Drought-tolerant; hates standing water

The most common bearded iris failure is planting rhizomes too deep. Per Penn State Extension, the rhizome top should be at or slightly above the soil surface in zones 4–7. Buried rhizomes fail to bloom and rot.

Divisions by height:

• Miniature Dwarf Bearded (MDB): under 8 inches
• Standard Dwarf Bearded (SDB): 8–15 inches; bloom earliest
• Intermediate Bearded (IB): 15–27 inches; bloom between dwarf and tall
• Tall Bearded (TB): over 27 inches; the classic large iris

Selected cultivars: