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Overview
Acorus gramineus 'Ogon' is an evergreen, grass-like perennial in the Acoraceae family, forming dense fans of linear, iris-like leaves 6–12 inches (15–30 cm) tall and spreading slowly by rhizomes to 12–18 inches (30–45 cm) wide. Leaves are ¼ inch (6 mm) wide, arching, with longitudinal stripes of gold-yellow and green — the yellow is most vivid in spring and where the plant receives 2–4 hours of direct light. New growth emerges chartreuse, maturing to golden-yellow. Despite its grass-like appearance, Acorus is not a true grass but belongs to its own family, more closely related to aroids. A greenish spadix, 2–3 inches (5–8 cm) long, appears sporadically in summer but is partially concealed within the foliage and rarely noticed. Crushed leaves release a faint citrus-sweet scent. The plant requires consistently moist to wet soil and tolerates standing water up to 2 inches (5 cm) deep. Growth slows substantially in dry conditions, and leaf tips brown if soil dries out for more than a few days during summer. Hardy to USDA zone 5, though foliage may be damaged below 15°F (-9°C) without snow cover.
Native Range
The species Acorus gramineus is native to eastern Asia, from Japan and Korea through China and into northern Vietnam, where it grows along stream margins, seeps, and wet meadows at low to moderate elevations. The cultivar 'Ogon' (meaning 'gold' in Japanese) was selected in Japan.Suggested Uses
Planted along pond margins, stream edges, and in rain gardens where soil remains consistently wet. Tolerates standing water to 2 inches (5 cm). Effective as a container plant in water features and tabletop gardens using a 2-gallon (7.5 L) or larger pot without a drainage hole. Combines with Carex, Juncus, and Iris species in riparian plantings.How to Identify
Appearance
Size & Dimensions
Height6" - 1'
Width/Spread1' - 1'6"
Reaches mature size in approximately 3 years
Bloom Information
A small, inconspicuous greenish spadix 2–3 inches (5–8 cm) long may appear in midsummer, emerging from the side of a leaf-like bract. Flowering is sporadic and often overlooked. Fruit set is uncommon in cultivation.Detailed Descriptions
Flower Description
Green (inconspicuous spadix)Foliage Description
Gold-yellow with green stripesGrowing Conditions
Sun Requirements
Requires 2-6 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Plant in consistently moist to wet soil in partial shade, spacing 10–12 inches (25–30 cm) apart for a continuous mat within 2–3 years. Tolerates full shade but golden colour is strongest with 2–4 hours of morning sun. In full sun, maintain constantly saturated soil to prevent leaf tip burn. Amend planting sites with compost to increase water retention. Supplemental irrigation is required during Pacific Northwest summer dry periods — do not allow the rootzone to dry. Apply 1 inch (2.5 cm) of compost mulch annually in spring. Division every 3–4 years in early spring maintains vigour.Pruning
Comb or cut out winter-damaged or brown foliage in early spring before new growth emerges. No other pruning is required. Division is done by lifting clumps in March–April and separating into sections with 3–5 fans each.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
early spring
Maintenance Level
lowContainer Growing
✓ Suitable for container growing
Minimum container size: 2 gallons