Ludwigia spp.
primrose-willows
Tropical and warm-temperate regions worldwide, many species in the Americas
Overview
Ludwigia spp. is a genus of about 80 species of aquatic and wetland herbs and shrubs in the evening-primrose family (Onagraceae), found across the tropical and warm-temperate regions of the world. Plants range from low creeping stems rooting at the nodes to upright forms 6 feet (1.8 m) tall, growing in mud, shallow water, or as floating mats. The leaves are simple and alternate or opposite, often turning red in cool or stressed conditions. Flowers open singly in the leaf axils, with four or five petals, usually yellow and occasionally white, 0.2 to 2 inches (0.5 to 5 cm) across depending on species. Bloom runs through summer and into autumn, followed by capsular seed pods. Several species, including L. peploides and L. grandiflora, spread rapidly across still water and are regulated as invasive aquatic weeds in many regions. In garden ponds the spreading species can choke open water within a season and need regular thinning.
Native Range
Ludwigia spp. occurs nearly worldwide in warm climates, with its greatest diversity in the Americas. Native North American species such as L. alternifolia and L. palustris grow in marshes, pond margins, and wet ditches across the eastern and central United States.Suggested Uses
Non-invasive Ludwigia spp. species are grown at pond and stream margins, in bog gardens, and in submerged containers for their yellow flowers and red-tinted foliage. They are spaced according to the spread of the species, with vigorous types confined to pots. The flowers attract bees and other insects through summer.How to Identify
Appearance
Size & Dimensions
Height6" - 6'
Width/Spread1' - 6'
Reaches mature size in approximately 1 years
Bloom Information
Flowering runs through the warm months, roughly June into September, with new blooms opening daily in the leaf axils. Each flower lasts about a day, and the display continues as long as warm weather holds. In frost-free regions some species flower nearly year-round.
Detailed Descriptions
Flower Description
yellow, occasionally whiteFoliage Description
green, often reddishGrowing Conditions
Sun Requirements
Requires 6-8 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
Most Ludwigia spp. grow in full sun in wet soil, shallow water, or at pond margins at pH 5.5 to 7.5, and the aquatic species need their roots permanently wet. Warmth drives growth, and the tender species are hardy only in USDA zones 8 and warmer, dying back where winters freeze. Plants spread quickly by rooting stems and need regular thinning in ponds to keep open water clear. Several species are restricted or banned from sale because they invade waterways. Growing them in submerged containers limits their spread. Aphids and leaf beetles can appear but rarely cause lasting harm.Pruning
Thin spreading Ludwigia spp. through summer by pulling or cutting back the rooting stems to keep them within bounds. Remove plant fragments from the water, since broken pieces root and form new plants. Cut frost-killed top growth back in autumn in colder zones.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
summer
Container Growing
✓ Suitable for container growing
Minimum container size: 3 gallons