Geranium maderense
giant herb-robert
Overview
Geranium maderense is a short-lived evergreen perennial or biennial in the cranesbill family, reaching 4–5 feet (1.2–1.5 m) tall and wide in flower, far larger than the 1–2 foot (30–60 cm) mounds typical of most cultivated cranesbills. In its first year it forms a wide rosette of deeply divided, fern-like leaves up to 24 inches (60 cm) across on reddish stalks. Once mature, usually in the second or third year, it sends up a branched dome carrying hundreds of magenta-pink flowers about 1.5 inches (4 cm) wide, each with a darker eye. The old leaf stalks bend downward and prop the heavy flowering stem like struts. The plant is monocarpic, dying after it sets seed, though it self-sows freely where conditions suit. It is tender, damaged below about 30°F (−1°C), and grown under glass or in mild coastal gardens elsewhere. Wind and hard frost are the main limits on growing it outdoors.
Native Range
Geranium maderense is native to the island of Madeira, where it grows in laurel forest clearings and on shaded banks. It is restricted in the wild and adapted to a mild, humid, frost-free climate.Suggested Uses
Geranium maderense is used in conservatories, frost-free courtyards, and mild coastal borders as a large flowering specimen, spaced 4–5 feet (1.2–1.5 m) apart. It combines with other tender perennials and self-sows into gravel and bare soil. Its tenderness and single flowering season make it short-lived in most gardens.How to Identify
Appearance
Size & Dimensions
Height4' - 5'
Width/Spread4' - 5'
Reaches mature size in approximately 3 years
Bloom Information
Flowering occurs in spring, from about March to May, once the plant reaches mature size in its second or third year. The branched dome carries hundreds of magenta-pink flowers with darker eyes over several weeks. After seed sets the plant dies, having flowered only once.
Detailed Descriptions
Flower Description
Magenta-pink with dark eyeFoliage Description
Mid-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
Geranium maderense grows in full sun to partial shade and moist, well-drained soil of average fertility, with a pH between 6.0 and 7.5. It is tender and damaged below about 30°F (−1°C), so it is grown under glass or in frost-free coastal gardens. Steady moisture supports the large rosette, while sharp drainage prevents winter rot. The downturned old leaf stalks brace the heavy flowering stem and are left in place rather than removed. The plant dies after flowering but leaves self-sown seedlings where the ground is bare. Little feeding is needed in reasonable soil.Pruning
Little pruning is needed. The downturned old leaf stalks are left in place because they support the flowering stem. After the plant flowers and sets seed it dies and can be cleared, leaving any self-sown seedlings to continue.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
summer
Container Growing
✓ Suitable for container growing
Minimum container size: 5 gallons