Propagating Acorus gramineus 'Variegatus' by Rhizome Division

Divide the rhizome of variegated Japanese sweet flag to multiply it. Honest note: it is a marginal bog plant, not a true aquatic, and slowly rots if kept fully submersed.

Overview

Acorus gramineus 'Variegatus' is the yellow-streaked, longer-leaved variegated form of Japanese sweet flag, native to Japan, Korea and eastern Asia. Leaves are long and narrow, reaching about 30 cm. It is a marginal wetland plant that can grow fully or partially submerged or in very moist soil, but it usually only flowers when at least partially submerged. It is commonly used around the edges of ponds and water gardens.

Propagation Method

Acorus gramineus spreads aggressively by rhizome, creating a nearly seamless groundcover where conditions suit it. It is propagated by dividing the fleshy rhizome and planting each base in shallow water or wet soil, which is also the way to keep the variegated leaf colouring true.

Step-by-Step

Lift an established clump from its pot, basket or pond margin.
Rinse the fleshy rhizome so you can see the growing points.
Divide the rhizome into sections, each with roots and a fan of leaves.
Plant each base in shallow water or constantly moist soil at the pond edge or in a paludarium.
Keep it wet and brightly lit while new leaves establish.

Conditions for Healthy Growth

Shallow water or very moist soil at a pond margin or in a paludarium.
Bright light, with cool to subtropical temperatures.
Grown emergent for best long-term health; full submersion is only short-term.
Tolerates a broad pH range and ordinary substrates.

Maintenance

Growth is slow, so it stays tidy and rarely needs hard pruning. Lift and divide congested clumps every couple of years to renew vigour and produce new plants. If you have tried it submersed in an aquarium, move it to an emergent position before the leaves begin to soften and rot.

Common Challenges

Slow, gradual rotting when kept permanently submerged underwater.
Variegation can dull in low light; give it bright conditions.
Aggressive rhizome spread at a pond margin if left unchecked.
Slow recovery from division, so divisions take time to bulk up.