Overview
Silphium laciniatum is a perennial herbaceous in the genus Silphium, part of the Asteraceae family. It typically grows around 2.0 m tall. Silphium laciniatum grows best in full sun, and tolerates most soils. Its UK hardiness is rated H7. Suggested uses include wildlife gardens, naturalized areas and prairie restoration. It is native to E North America.
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 laciniatum is a tall, taprooted perennial herbaceous species in the Asteraceae, native to eastern North America. It typically grows to around 2.0 m and produces noticeable foliage with a resinous scent; flowering in the UK takes place between July and September. Treat it as a structural perennial rather than a low-growing ground cover. Give the compass plant a full sun position on soil that is moist but well drained; it tolerates sandy, loamy and clay soils provided they do not remain waterlogged. The UK hardiness rating H7 means it is fully hardy and will withstand typical winter conditions in Britain. Allow room for its mature height when siting and avoid shading from taller trees or hedges. Where it works best is in wildlife-orientated borders, naturalised areas and prairie-style plantings where a tall, sun-loving specimen is needed. It can form a strong vertical element at the back of a mixed border or within meadow restorations and offers foliage fragrance that can be appreciated from neighbouring paths. Position so the scented leaves are near areas where people will notice them.
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 laciniatum size, habit and characteristics
- Plant type
- Perennial herbaceous
- Height
- 2.0 m
- Suggested uses
- Wildlife gardens, naturalized areas, prairie restoration
- Native to
- E North America
- Fragrance
- Foliage
Care notes
Pruning and caring for Silphium laciniatum
- Cultivation
- Prefers well-drained soils; drought tolerant once established; minimal maintenance
- Pruning
- Cut back in late winter or early spring to encourage new growth
- Propagation
- Seed, division
Frequently asked questions
How do I grow Silphium laciniatum?
Prefers well-drained soils; drought tolerant once established; minimal maintenance.
Where is the best place to plant Silphium laciniatum?
Silphium laciniatum prefers full sun. It suits full sun positions.
What soil does Silphium laciniatum need?
Silphium laciniatum 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 laciniatum?
Cut back in late winter or early spring to encourage new growth.
How big does Silphium laciniatum grow?
Silphium laciniatum reaches a height of 2.0 m.
Is Silphium laciniatum hardy in the UK?
Silphium laciniatum 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 laciniatum?
Seed, division.
From the Fenn Plants journal
- Notes on DaffodilsWhen to plant daffodil bulbs in the UK, how deep, how to naturalise them in grass, why daffodils stop flowering (“blindness”), and why you should never mix cut daffodils with other flowers.
- Keeping Your NerveHow to garden through a heatwave — the best time to water, why deep soaks beat daily sprinkles, caring for pots and vulnerable plants, and why you can let the lawn go brown.
- Made to LastHow to clean, store and protect garden pots and planters — the frost-proof vs frost-resistant difference, winter care for terracotta and ceramic, and how to reuse a broken pot.
More in the Silphium genus
- Silphium PerfoliatumCup Plant
- Silphium perfoliatum (Dixter Form)Cup Plant
- Silphium terebinthinaceumprairie burdock
- Silphium Morhii