A VERY PRICKLY ISSUE: Not everyone agrees but thistles add elegance and attract pollinators
- Nigel Colborn explains why he loves thistles, with their sculpted leaves and elegant flowers – which often appear in art and design
- UK-based gardening expert says Cornflowers, knapweeds and related plants have similar flower shapes to thistles
- True thistles such as Cirsium are long-lived perennials and can be divided in spring or autumn
Want to know a secret? I love thistles. Despite being prickly weeds, they are beautiful. That must be why their sculpted leaves and elegant flowers often appear in art and design.
Luckily, some varieties are painless. For example, the leaves of the meadow thistle Cirsium dissectum are soft and harmless. The 60cm stems carry handsome purple-red flowers.
Plume thistle C. rivulare also has soft leaves and purple-red flowers. In moisture-retaining soil, the stems grow to a metre and flower for weeks.
The equally harmless melancholy thistle C. heterophyllum has similar purple flowers on tall stems. One lovely variety, Pink Blush, has white, shaving brush flowers peppered with shocking pink petals — and it is currently on offer at crocus.co.uk.
Nigel Colborn explains why he loves thistles, with their sculpted leaves and elegant flowers – which often appear in art and design
For grandeur, the vast biennial cotton thistle Onopordum acanthium beats the lot. Huge, felty, silver-grey leaves develop in its first summer. In year two, fiercely prickled, multi-branched stems grow 2m high and are laden with maroon blooms. Before dying, it launches clouds of seed-carrying thistledown.
That name, Onopordum, is rather rude. Derived from Greek, it combines ‘donkey’ with ‘breaking wind’. So, if a donkey munches too many Onopordum leaves, its owner could experience a jet-propelled ride.
The classic thistle flower, with tufty petals above a rotund seed box, is not exclusive. Cornflowers, knapweeds and related plants have similar flower shapes.
Cornflower garden varieties are available in a mix of colours, but nothing beats the azure of a wild cornflower. Seeds for mine came from France 31 years ago. They self-sow faithfully every year.
The most popular non-thistle thistle is Echinops, globe thistle. Coming into flower now, the most popular, E. ritro, grows 60cm tall with spiky blue flowers. The tallest, E. sphaerocephalus, has ice-grey flowers on stems that grow two metres tall.
Globe thistles have grey-green foliage which looks attractive for most of the summer. They’re popular with pollinators, too — so ideal for bee keepers and nature-loving gardeners.
Most thistle-like plants are simple to grow and propagate. I’ve seen saw-wort growing wild in the short, cliff-top grasses of North Cornwall. In a rock garden it would thrive with other Alpines, or could garnish the front of a sunny border.
SAVE FOR HOT SPOTS
True thistles such as Cirsium are long-lived perennials and can be divided in spring or autumn. They prefer moist, fertile soil and flower best in sunny positions. Like all other plants mentioned, they’re hardy and fully weather-proof.
Globe thistles fare best in full sun and free-draining soil. Taller varieties may need support in summer, using metal linking stakes or canes and soft string.
Our native sea holly grows in sand dunes and beach margins well above the tidal zone. As you soon discover strolling barefoot among those dunes, the plants arepainfully prickly. Grow garden varieties in fast-draining soil and full sun. Those with blue stems and leaves colour-up best when grown in hot spots.
Biennial sea hollies such as E. giganteum Miss Willmott’s Ghost are prolific self-seeders. Limit this by removing most plants before they run to seed.