1 Salvia nemorosa 'Caradonna’ from the mildly aromatic silvery green leaves to the violet flower spikes with purple stems. Bees love the flowers that stay looking sharp long after the petals fall, thanks to papery bracts that hold their colour. Dead-heading – either little and often or in one go – encourages new flowering side-shoots till October. 'Caradonna’ loves sun; use it as a purple ribbon through late season grasses or, at 18in (45cm), it is the perfect centrepiece for a pot.