Calla palustris
marsh calla
Northern Hemisphere (boreal and temperate wetlands)
Overview
Calla palustris is a rhizomatous aquatic perennial of bogs and pond margins, growing 6 to 10 inches (15 to 25 cm) tall with creeping stems that root at the nodes along the water edge. The glossy, heart-shaped leaves measure 2 to 4 inches (5 to 10 cm) long on long stalks held just above the water or wet mud. From late spring into summer it produces a flat white spathe 1.5 to 2.5 inches (4 to 6 cm) long that wraps around a short yellow-green spadix of tiny flowers. Pollinated flowers ripen into a tight cluster of red berries by late summer. The species spreads by floating, branching rhizomes that form loose colonies at the margins of still or slow water. Native to cool wetlands across the Northern Hemisphere, it requires constantly wet to shallowly flooded ground and will not survive in ordinary garden soil that dries out. All parts contain calcium oxalate crystals that irritate the mouth and digestive tract if eaten raw. Growth is restrained, and the plant tolerates only shallow water no more than a few inches deep.
Native Range
Native to cool temperate and boreal wetlands across the Northern Hemisphere, including northern North America, Europe, and Asia. It grows in bogs, marshes, swamps, and at the edges of ponds and slow streams.Suggested Uses
Used at the margins of ponds, bog gardens, and rain gardens, and in shallow water features. It suits naturalized wetland plantings in cool climates. The flowers draw flies and beetles that pollinate them, and waterfowl take the berries.How to Identify
Appearance
Size & Dimensions
Height6" - 10"
Width/Spread1' - 2'
Bloom Information
Flowering occurs from late spring into early summer, generally May through July. A flat white spathe 1.5 to 2.5 inches (4 to 6 cm) long surrounds a short spadix of small flowers. Each spathe lasts about 1 to 2 weeks. Red berry clusters develop by late summer.
Detailed Descriptions
Flower Description
white spathe with yellow-green spadixFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 4-8 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
Grow in full sun to part shade in constantly wet, acidic soil or in shallow water up to 4 inches (10 cm) deep. Calla palustris grows in mucky, humus-rich substrates with a pH of 4.5 to 6.5 and never tolerates drying out. Position it at pond and bog margins where the rhizome can creep across saturated ground. It is cold hardy in USDA zones 3 through 8. In containers, use a heavy aquatic mix and stand the pot in water. The plant declines quickly if the root zone dries, even briefly.Pruning
Little pruning is needed. Yellowing leaves and spent flower stalks can be removed at the base during the growing season. Thin crowded rhizomes in spring to control spread. Cut back frost-damaged foliage in late autumn.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
early spring
Container Growing
✓ Suitable for container growing
Minimum container size: 2 gallons