Overview
Silphium Perfoliatum is a perennial in the genus Silphium, part of the Asteraceae family. It typically grows around 2.5 m tall. Silphium Perfoliatum grows best in full sun, and tolerates most soils. Its UK hardiness is rated H7. Suggested uses include wildlife gardens, naturalistic plantings and rain gardens. It is native to Alabama, Arkansas, Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Massachusetts, Michigan and Minnesota.
About
Silphium Perfoliatum is a species in the genus Silphium. It is notable for producing its flowers in the UK from July to September. Detailed cultivation requirements vary between sources, so check specialist references before purchase. When sourcing plants, confirm botanical identity with the supplier.
About the genus
Silphium is an unidentified plant that was used in classical antiquity as a seasoning, perfume, aphrodisiac, and medicine.
Wikipedia contributors, "Silphium", CC BY-SA 4.0 — Silphium
In the garden
Silphium Perfoliatum is a botanical species placed in the genus Silphium. As a named taxon it appears in specialist lists and seed catalogues; available information should be checked against nursery labels and authoritative references to confirm identity before planting. Practical guidance on siting, soil type and winter hardiness for this species should be sought from specialist nurseries, botanic gardens or published monographs that cover the genus Silphium. When obtaining material, ask suppliers for provenance and any cultivation notes they can provide; that information is the most reliable way to match a plant to a particular plot or microclimate. For garden planning, use flowering time to schedule colour and pollinator resources: Silphium Perfoliatum flowers in the UK from July to September. That predictable mid- to late-summer display can help fill summer border gaps or complement summer-flowering perennials when confirmed horticultural details are available from the plant source.
Growing conditions
Best soil and position for Silphium
- Sunlight
- Full sun
- Soil type
- Sandy, Loamy, Clay
- Soil moisture
- Moist but well-drained
- Exposure
- Full sun
- UK hardiness
- H7
Plant details
Silphium Perfoliatum size, habit and characteristics
- Plant type
- Perennial
- Height
- 2.5 m
- Suggested uses
- Wildlife gardens, naturalistic plantings, rain gardens
- Native to
- Alabama, Arkansas, Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Massachusetts, Michigan, Minnesota
Care notes
Pruning and caring for Silphium Perfoliatum
- Cultivation
- Prefers moist, fertile soil; tolerates wet conditions; avoid drought stress
- Pruning
- Cut back in late winter or early spring to encourage fresh growth
- Propagation
- Seed, division
Frequently asked questions
How do I grow Silphium Perfoliatum?
Prefers moist, fertile soil; tolerates wet conditions; avoid drought stress.
Where is the best place to plant Silphium Perfoliatum?
Silphium Perfoliatum prefers full sun. It suits full sun positions.
What soil does Silphium Perfoliatum need?
Silphium Perfoliatum is adaptable and grows happily in most soil types, including sandy, loamy and clay. Aim for soil that stays moist but well-drained.
How do I prune Silphium Perfoliatum?
Cut back in late winter or early spring to encourage fresh growth.
How big does Silphium Perfoliatum grow?
Silphium Perfoliatum reaches a height of 2.5 m.
Is Silphium Perfoliatum hardy in the UK?
Silphium Perfoliatum has an RHS hardiness rating of H7, meaning it is fully hardy throughout the UK, tolerating temperatures below -20°C.
How do I propagate Silphium Perfoliatum?
Seed, division.
