Gardening: Is it too cold to move my butterfly bush?

Winter is not the best time to transplant or prune buddleia

Q: I want to transplant a “dwarf” buddleia – which is much bigger than I expected – from a built-up flower bed to the ground. Is it too late/cold to do this? Should I cut back all the stems before I move it? It only finished flowering mid-November. Grainne Ward, Co Kildare

Buddleia, or the butterfly bush as it’s commonly known, is a hardy, drought-resistant, easy-to-grow, deciduous or semi-evergreen shrub that’s prized for its colourful display of pollinator-friendly flowers. On a warm, sunny summer’s day, it’s not unusual to spot established plants covered with dozens of butterflies feeding from these fragrant, nectar-rich blooms, always a magical sight.

Well-known traditional varieties such as Buddleia davidii Black Knight can quickly grow into sizeable, sprawling shrubs and need to be hard-pruned annually to prevent them outgrowing their allotted space. They can also self-seed abundantly, attracting criticism from environmentalists concerned that they could displace native species. But the new dwarf varieties introduced in the last decade have been bred to be more compact as well as almost sterile, with the result that they flower for much longer (hence your plant blooming into November). They also very rarely produce viable seed, so pose little threat to native species.

Winter is not the best time to transplant or prune most species of buddleia. Instead both are typically best done in early spring (late March-mid April).


To prune your butterfly bush, use a sharp, clean secateurs to cut the main branches back just above a pair of buds to create a low, woody permanent framework, leaving roughly three-four buds on each branch. This will encourage generous flowering and prevent it getting too large. To move it, use a sharp spade to dig around the edges of the root ball, making sure to preserve as much of the latter as you can as you gently excavate it out of the ground. Replant quickly into a pre-dug, generous-sized hole, making sure to do so to the original planting depth, and then water generously. Your plant will need to be watered in any subsequent prolonged dry spells in the months after replanting to ensure it establishes well. Bear in mind too that the butterfly bush likes a warm, sunny position and a moderately fertile, moist but free-draining soil.

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Fionnuala Fallon

Fionnuala Fallon

Fionnuala Fallon is an Irish Times contributor specialising in gardening