Acorus

Bloom Time

Acorus is grown primarily for its foliage rather than its flowers. The small, greenish-yellow flower spikes (spadix) are inconspicuous and often hidden among the leaves. The ornamental value comes entirely from the elegant, sword-shaped leaves, which provide year-round textural interest in moist and aquatic settings.

Size and Growth Habit

Acorus ranges from miniature cultivars just 6 inches tall (A. gramineus 'Minimus') to the full-size Acorus calamus reaching 3 to 4 feet. Upright, sword-shaped leaves grow in fan-like clumps that slowly spread by rhizomes. Many cultivars feature attractive variegation in cream, gold, or green-and-white striped patterns.

Hardiness Zones

Acorus gramineus is hardy in Zones 6 through 11, while Acorus calamus extends the range to Zone 4. Both species tolerate a wide range of conditions from standing water to consistently moist garden soil.

Light Requirements

Acorus grows well in full sun to full shade, making it one of the most light-adaptable plants available to gardeners. Variegated forms develop their best coloring in bright indirect light or morning sun.

Soil and Water Requirements

Acorus thrives in consistently moist to wet conditions, including standing water up to 4 inches deep. It is ideal for pond margins, bog gardens, rain gardens, and stream banks. While it prefers wet soil, established plants of some species tolerate average garden moisture if watered regularly.

Pruning

Remove tattered or brown leaves at any time to maintain a neat appearance. Division of overcrowded clumps in spring rejuvenates plants and provides material for new plantings.

Summer Care

Ensure soil stays consistently moist during summer. Container plants in shallow water may need daily attention in extreme heat. The foliage remains attractive throughout the growing season with virtually no care required.

Winter Care

Hardy species are fully cold-tolerant within their recommended zones. In colder areas, submerge aquatic plantings below the ice line or mulch heavily over the crown. Evergreen foliage may brown at the tips in harsh winters but recovers reliably in spring.

Companion Plants

Pests and Diseases

• Spider mites: Can appear in hot, dry conditions on container plants. Increase humidity and mist regularly.
• Acorus is generally pest and disease-free, which is one of its greatest assets as a landscape plant.

Common Varieties

Toxicity

Acorus is generally considered non-toxic to humans and pets. The roots of Acorus calamus have been used medicinally for centuries. As a garden plant, acorus poses no significant toxicity risk.

Care Difficulty

Acorus is one of the easiest plants to grow, provided it has adequate moisture. It tolerates a huge range of light conditions, resists virtually all pests, and requires almost no maintenance beyond keeping the soil moist.