Pruning Globe thistle

Globe thistle requires minimal pruning, but a couple of seasonal cuts will keep plants tidy and vigorous. The main pruning window is March, just as new growth begins to emerge at the base, and again in November after flowering has finished and foliage starts to decline. In November, once the spherical blue flowerheads have faded and the plant looks tatty, cut back all stems to around 10–15 cm above ground level. Use clean, sharp secateurs or loppers for thicker stems. Many gardeners prefer to leave the architectural seedheads standing through winter—they look striking with frost and provide food for finches—but remove them by late winter to prevent self-seeding and to make way for fresh growth. The dried stems can be quite tough, so sharp tools make the job easier. In March, tidy up any remaining dead material you left over winter and cut right back to the emerging basal rosette of leaves. This is also the time to remove any damaged or frost-affected growth. If your clump has become congested or flowering has declined, March is the ideal moment to lift and divide the plant. Use a spade to slice through the woody crown, retaining vigorous outer sections and discarding the tired centre. Globe thistle doesn't require deadheading to prolong flowering, but if you want to prevent self-seeding or prefer a neater appearance, snip off spent flowerheads in late summer. The plant flowers once per season, so deadheading won't encourage a second flush. Wear gloves when handling—the foliage is spiny and can irritate skin.