UK pruning guide · RHS timing
When to prune zantedeschia 'picasso' in the UK
Why the timing differs here
For shrubs that flower on the current season's growth, the RHS times pruning to early or mid spring — after severe weather has passed and once the growth buds begin to swell. In Britain that is usually March into April rather than the February common in warmer regions; prune too early and the new shoots meet a late frost.
How to prune zantedeschia 'picasso'
Remove faded spathes at stem level as soon as they begin to collapse. Cut back all foliage to soil level once it yellows. Do not pull — cut cleanly to avoid disturbing the rhizome.
Zantedeschia 'Picasso', with its distinctive white-speckled purple spathe, needs the same care as other coloured calla cultivars. Deadhead spent flowers promptly by cutting at the stem base. Once flowering ends and the foliage yellows at season's end, cut all growth to the ground and allow the rhizome to go dormant.
More zantedeschia 'picasso' care for British gardens
Care at a glance
Pruning zantedeschia 'picasso' in the UK — FAQ
When should I prune zantedeschia 'picasso' in the UK?
Prune zantedeschia 'picasso' in early to mid spring. For shrubs that flower on the current season's growth, the RHS times pruning to early or mid spring — after severe weather has passed and once the growth buds begin to swell. In Britain that is usually March into April rather than the February common in warmer regions; prune too early and the new shoots meet a late frost.
Is it illegal to prune zantedeschia 'picasso' in spring or summer in the UK?
There is no nesting-bird restriction that realistically applies to zantedeschia 'picasso', since birds do not nest in it. The Wildlife and Countryside Act 1981 still protects any active nest you do find anywhere in the garden — the rule is about the nest, not the plant.
How do you prune zantedeschia 'picasso'?
Remove faded spathes at stem level as soon as they begin to collapse. Cut back all foliage to soil level once it yellows. Do not pull — cut cleanly to avoid disturbing the rhizome.
How often does zantedeschia 'picasso' need pruning in a British garden?
Deadhead throughout flowering; full annual cut-back. Zantedeschia 'Picasso', with its distinctive white-speckled purple spathe, needs the same care as other coloured calla cultivars. Deadhead spent flowers promptly by cutting at the stem base. Once flowering ends and the foliage yellows at season's end, cut all growth to the ground and allow the rhizome to go dormant.
Why is UK pruning timing different from American advice?
Most pruning guides online are written for US conditions and anchored to USDA zones. Britain's maritime climate gives milder winters but later, less predictable last frosts — from March in the south-west to mid-May in the north — so the RHS advises against winter pruning for most plants: it pushes out soft growth that a late frost then kills. Britain also has the nesting-bird law, which has no US equivalent.