Achillea kellereri

The Achillea kellereri is a yarrow with long leaves intricately carved like goldsmithing; it is also one of the most luminous plants with silver foliage in rock or dry gardens. The plant forms a cushion with a regular shape, composed of finely toothed long leaves, superbly silver-grey in winter, and almost white in summer due to heat and drought. In spring, its pure white flowers dominate the cushion of leaves. The garden thrives in poor, rocky soils, perfectly drained, without watering in summer.

The Achillea (x) kellereri is a spontaneous hybrid probably resulting from a natural cross-breeding with the Achillea Clavennae and another species originating from central Europe, the eastern and southern Alps, to the Balkan Peninsula. All these plants belong to the Asteraceae family. Kellerer's yarrow has a weak sucker, slowly forming a beautifully rounded cushion, 25 cm (10in) tall when flowering, 10 cm (4in) for foliage, depending on the growing conditions. It spreads quite slowly on the ground, up to 25 cm (10in), through stolons. Its foliage remains throughout the year, unaffected by winter's harshness or summer's heat. Finely toothed along the edges, narrow and covered with a silver-grey fuzz that becomes very light in July-August, it offers a fluffy appearance that one can enjoy touching. Flowering occurs in April-May, depending on the climate. The numerous flat umbel flower heads are composed of small inflorescences called heads. These heads are pure white with a creamy yellow centre.

All yarrows love the sun and have excellent hardiness. The Achillea kellereri, requiring very little maintenance, is a ground cover cushion suitable for rock gardens and as a border plant. This yarrow adds a precious aspect to the garden. It is non-invasive, hardy, water-efficient, and ideal for dry slopes. It can be associated with other ground cover or cushion plants such as Geranium sanguineum, Erigeron karvinskianus, and Nepeta x faassenii. Many combinations are possible, with dwarf Teucrium, Artemisia lanata, Centaurea bella, Thymus (hirsutus, ciliatus, lanigerus), or other yarrows (millefolium, coarctata, nobilis).