When planting, incorporate compost to improve drainage and fertility, spacing plants 30-45cm (12-18in) apart and watering thoroughly.
To keep the plants blooming throughout the season, promptly remove flower spikes as soon as they begin to fade - this deadheading encourages the plants to produce more flowers rather than putting energy into seed production.
In early spring, apply a generous 5-7cm (2-3in) mulch of well-rotted garden compost or manure around the base of the plants to retain moisture, suppress weeds, and provide essential nutrients as it breaks down. Ensure the mulch is spread evenly, but keep it away from the stems to prevent rot. A supplementary granular fertiliser (such as the mineral based Growmore) is advised in the early part of the season, once the plants begin to sprout.
Regular watering, particularly in dry spells, will help maintain healthy growth, but be careful not to waterlog the soil, as these salvias prefer well-drained conditions.
Finally, consider providing some protection in exposed or colder regions of the UK by covering with a double layer of horticultural fleece or dry mulch (bark chippings/ composted pine needles) to insulate the roots, or by using a cloche to protect the plants against hard frosts.