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Romneya coulteri
Matilija poppy
Southern California (Los Angeles, San Diego, Riverside counties) and Baja California, Mexico; chaparral and dry canyon habitatsLearn more
Overview
A large, spreading, semi-woody perennial subshrub in the family Papaveraceae, native to the chaparral, dry canyons, and coastal scrub of southern California and Baja California, Mexico. Plants establish slowly from the root but eventually form extensive spreading colonies 4–8 feet (1.2–2.4 m) tall and 6 feet (1.8 m) or more wide via deep, wide-spreading rhizomes. The deeply pinnately lobed, blue-gray to glaucous leaves 3–6 inches (8–15 cm) long are attractively textured and provide year-round structure in mild climates. From late May through July, the plant produces the largest flowers of any native North American perennial: bowl-shaped blooms 4–9 inches (10–23 cm) across with six to nine crinkled, papery white petals surrounding a prominent boss of golden-yellow stamens, resembling a fried egg — giving rise to the common nickname 'fried egg plant.' The flowers have a light, pleasant fragrance. Romneya coulteri is fiercely drought-tolerant once established but deeply intolerant of disturbance: it virtually cannot be transplanted after establishment, and spreading rhizomes are extremely difficult to contain or remove. Mildly toxic if ingested (alkaloids in foliage and sap).
Native Range
Native to the dry chaparral, rocky canyon slopes, and disturbed roadsides of southern California (Los Angeles, San Diego, Riverside counties) and Baja California, Mexico, growing in well-drained, often poor, rocky or sandy soil in full sun.Suggested Uses
Planted as a bold specimen or massed in large-scale dry gardens, California native plantings, and naturalized slopes at 5–6 foot (1.5–1.8 m) spacing — allow full room for mature spread. The enormous white flowers and blue-gray foliage create a dramatic structural presence in summer. Combine with other drought-tolerant California natives (ceanothus, salvia, artemisia). Not appropriate for small gardens or areas where rhizome spread cannot be managed. Outstanding for erosion control on dry slopes.How to Identify
Appearance
Size & Dimensions
Height4' - 8'
Width/Spread6' - 10'
Bloom Information
Blooms late May through July in zones 7–10, with individual flowers lasting 2–4 days and new buds opening in succession over 4–6 weeks. The flowers are most productive during the first few years of establishment; mature colonies bloom abundantly. In the Pacific Northwest, plants that receive summer heat bloom reliably in June–July. The fragrant flowers are most effective as a bold summer display in naturalistic and dry garden settings.Detailed Descriptions
Flower Description
pure white crinkled papery petals surrounding prominent golden-yellow stamens; bowl-shaped, 4–9 inches across; lightly fragrantFoliage Description
blue-gray to glaucous; deeply pinnately lobed, 3–6 inches longGrowing 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
Plant in full sun in lean, sharply drained, sandy or rocky, neutral to slightly alkaline soil with a pH of 6.5–8.0. Once established, extremely drought-tolerant — summer watering should be minimal to none in dry-summer climates. Avoid amending soil with compost or fertilizer; lean, infertile conditions are preferred. R. coulteri resents root disturbance profoundly — purchase small plants in containers and disturb the roots as little as possible when planting. Once established, the plant is nearly impossible to move or eradicate. The spreading rhizomes are aggressive — install a deep root barrier (18–24 inches / 45–60 cm) at planting if containment is needed. Hardy to zone 7 (0°F / -18°C) with good drainage.Pruning
Cut all stems back to 6–12 inches (15–30 cm) above ground in late winter (February–March) before new growth begins — this annual hard cutback is essential and stimulates the most vigorous growth and flowering. Do not cut back in fall; winter stems provide some frost protection. Contain spread by cutting back rhizome runners at the perimeter with a sharp spade in early spring.Pruning Schedule
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early spring