As a gardener I am not a fan of berberis. As a consumer it is quite different, they are often stunning in flower and provide a useful evergreen structure to the garden. This disparity can be explained by using The Gardener’s Prickle Equation. This calculation involves complicated variables and whimsies. In short, the beauty of any given plant, be it herb, tree or shrub, must outweigh the pain by a factor of four. I adore this Berberis valdiviana as both a worker and an observer. In spring it is festooned with hanging panicles of turmeric yellow flowers which hum with the gratitude of gorging insects. This evergreen shrub from Chile can reach 3m which, if you have the space for it, will fill your garden with floriferous sunshine in spring. Added to this it is less spiky than most of its relatives. The result of the horti-maths is positive. My cold, cold heart is thawing.