Germination temperature
Mild spring conditions; sow in mid-spring outdoors or in a cool room or cold frame.
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Great globe thistle is a tall, very hardy perennial with spiny leaves and round, silvery-white to pale blue flower heads. It is easy from seed sown in spring and thrives in sun and poor, well-drained soil.
Mild spring conditions; sow in mid-spring outdoors or in a cool room or cold frame.
Shallow: a thin covering, about the seed's own thickness.
About 2-3 weeks.
Full sun; tolerates anything but deep shade.
None needed.
Either; move seedlings while small because the root goes deep.
The seeds are long, narrow achenes (7-10 mm) with a short fringe of scales. Sow them as they are; there is no need to remove the fringe.
Not needed. The seed coat is not hard.
Not needed for spring sowing. Seed sown outdoors in autumn simply goes through winter naturally and comes up in spring.
Not needed. Keep the seedbed evenly moist instead.
Mild spring weather suits it. In temperate climates sow in mid-spring, or in autumn outdoors. In India it is best suited to hill gardens; on the plains sow in the cool season so seedlings establish before hot, wet weather.
Cover with only a thin layer of fine compost or soil, about the seed's own thickness.
A gritty, free-draining seed compost in modules or deep cells, or a fine outdoor seedbed. Chalk, loam or sandy soil of any pH suits the plant later.
Keep evenly moist until seedlings are up, then water less. Wet, cold compost rots seedlings.
Give full light as soon as seedlings appear.
Usually about 2-3 weeks.
Plant out young plants while they are still small, in spring or early autumn, into a sunny, open spot with good drainage. They develop a deep root and do not like being moved once established.
Allow about 50 cm (20 in) between plants; flowering stems reach 1-2 m, so place them at the back of a border.
Water young plants regularly through their first season until they root deeply. Plants often make a leaf rosette in the first year and flower from the second year.
Cause: cold, wet compost. Fix: use a gritty mix, water from below and only when the surface starts to dry.
Cause: rich soil, shade or wind. Fix: grow in lean soil and full sun, and give a stake in exposed spots.
Cause: too much shade. Fix: move or divide into a sunnier position in spring.
Cause: aphids, the main pest RHS lists. Fix: wash them off or leave them to ladybirds and other predators; the plant is otherwise generally disease-free.
Cause: self-sown seed. Fix: cut faded heads before they shed seed; the species can escape into fields and roadsides outside its native range.
A light general feed in spring is enough. Rich soil gives soft, floppy growth.
Established plants tolerate dry spells and need watering only in long droughts.
Leaves and flower heads are spiny; wear gloves when cutting or dividing.
Cut heads just before the florets open for fresh or dried arrangements; hang them upside down in a dry, airy place.
Once settled, a clump can stay in the same place for many years. Plants take about 2-5 years to reach full size, so leave space for them when planning the border.
Sow in spring for tall, hardy globe thistles that flower year after year.
Often from the second year. In the first season many plants only form a rosette of spiny leaves while they build their deep root.
It is better not to: the root goes deep and plants resent disturbance. Divide in spring or take root cuttings while dormant if you need more plants.
It is very hardy to cold and does best in sunny, well-drained hill gardens. On the hot, humid plains grow it in the cool season and in sharply drained soil.
It is a garden perennial of the daisy family, not one of the creeping field thistles, and it does not spread by running roots. It can self-sow freely, though, and has escaped into fields and roadsides outside its native Europe and Asia, so remove faded heads before the seed ripens.