Abelia 'Kaleidoscope' has long-lasting, fragrant flowers and variegated foliage in yellow, green, orange and red.

Acaena inermis 'Purpurea' is an excellent ground cover for crawling over gravel paths or stones with gorgeous purple-blue-grey foliage.

Acaena saccaticupula 'Blue Haze' is an excellent ground cover with powder blue foliage.

Acanthus hungaricus 'White Lips' is a dramatic bear's breeches with spikes of light plum hoods and wide, white lips.

Acanthus mollis 'Hollard's Gold' is a very special bear's breeches with new leaves emerging gold or chartreuse.

Acanthus 'Whitewater' forms vigorous mounds of variegated foliage and pink stems holding white flowers.

Acanthus 'Morning Candle' is very free-flowering with extra tall and stately spires of mauve bracts and white flowers up to four feet tall.

Achillea ageratifolia is an unusual yarrow forming aromatic, silver-green, mounds covered in pure white daisies with light yellow centres.

Achillea filipendulina ‘Gold Plate’ is a yarrow that produces masses of large golden-yellow flowers on tall stems.

Achillea millefolium, the common yarrow, is an important nectar source and host plant for a diversity of insects.

Achillea 'Apricot Delight' has large, flat-topped flower clusters in various shades of pink on strong stems up to 24 inches with fragrant, fern-like foliage.

Achillea Desert Eve 'Deep Rose' is a yarrow with dark pink flowers with yellow centres above fragrant, fern-like foliage.

Achillea Desert Eve 'Red Improved' has brick-red flowers above fragrant, fern-like foliage.

Achillea Desert Eve Terracotta has flowers in shades of yellow, orange and rusty orange.

Achillea millefolium 'Heartthrob' has large, flat-topped flower clusters with colourfast, velvet-red flowers above dissected, fern-like foliage.

Achillea millefolium 'New Vintage Red' has large, flat-topped flower clusters of bright red with white centres.

Achillea millefolium 'New Vintage Rose' has large, flat-topped flower clusters of rose pink with white eyes on strong stems to 24 inches.

Achillea 'Sassy Summer Taffy' has large, flat-topped flower clusters in shades of deep rose pink, salmon pink, light pink, and peachy pink on tall, strong stems to 32 inches

Achillea ptarmica 'Peter Cottontail' is a unique yarrow with white, button-like flowers held in low, cloud-like mounds.

Achillea tomentosa ‘Goldie’ is a woolly yarrow that produces clusters of yellow flowers on top of evergreen, fuzzy foliage.

Aconitum 'Cloudy' is a gorgeous bicolour monkshood with blue and white flowers.

The tall stems and purple-blue flowers of the monkshood Aconitum 'Arendsii' offer a substitute for Delphinium for shadier conditions.