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Argentina egedii
Pacific silverweed
Pacific coast of North America from southern Alaska to northern California
Overview
Argentina egedii is a herbaceous perennial forming low spreading mats 4-12 inches (10-30 cm) tall via long red stolons that root at nodes. Leaves are pinnately compound, 4-12 inches (10-30 cm) long, with 7-25 oblong leaflets that are dull green above and densely covered in silvery-white hairs beneath. Solitary yellow flowers are 0.6-1 inch (1.5-2.5 cm) across with five rounded petals, borne on stalks 4-8 inches (10-20 cm) tall from May through August. Fruit is a small dry achene cluster, 0.2 inch (5 mm) across. New stolons can extend 12-24 inches (30-60 cm) per growing season; a single plant can occupy a 6-foot (1.8 m) circle within 3 years. Foliage emerges in April and dies back to ground level after the first hard frost in zones 4-7. Tolerates seasonal flooding and brackish water in coastal habitats; salt tolerance is high. Stolons can extend beyond intended planting areas in moist garden soils; this spread is the primary drawback in cultivation.
Native Range
Native to coastal Pacific North America from southern Alaska through British Columbia, Washington, Oregon, and northern California. Grows in coastal salt marshes, brackish flats, sandy beaches, and tidal estuaries within 0.5 mile (0.8 km) of saltwater. Also occurs along low-elevation freshwater shorelines in Pacific coastal watersheds.Suggested Uses
Used as a ground cover in coastal native gardens, salt-tolerant beach plantings, and rain garden margins, spaced 18-24 inches (45-60 cm) apart. Plantings combine with Carex obnupta, Achillea millefolium, and Festuca rubra on moist coastal sites. The aggressive stolon spread typically excludes use in small-scale formal beds and mixed perennial borders.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Width/Spread3' - 6'
Reaches mature size in approximately 3 years
Bloom Information
Blooms May through August along the Pacific coast, with peak flowering June through July. Individual flowers last 4-6 days; total bloom period extends 10-14 weeks per plant. Cooler maritime climates produce a longer, more uniform bloom; warm summers compress flowering to 6-8 weeks.
Detailed Descriptions
Foliage Description
dull green above, silvery-white beneathGrowing Conditions
Sun Requirements
Requires 5-8 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
Water at planting and during the first 4-6 weeks of establishment; established plants in coastal soils require no irrigation. Inland plantings tolerate drought once established but become semi-dormant in dry summers, regrowing after fall rains. Stolons spread readily in moist soils; root pruning along bed edges every 1-2 years contains the spread. Powdery mildew and rust occasionally appear on foliage in humid summers; plants typically recover the following season. Fertilization is not required in fertile coastal soils. The dense mat suppresses most annual weeds once fully established.Pruning
Old leaves are removed in early spring before new growth emerges; the previous season's foliage typically dies back over winter. Spent flower stalks can be cut to ground level after seeds disperse in late summer. Stolons that extend beyond intended planting areas can be pulled or cut at the parent crown in any season.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: 3 gallons