Achillea umbellata

The Achillea umbellata, also known as the Umbellate yarrow, is a small perennial plant that grows close to the ground, forming delightful silver cushions that are as pleasing to the eye as they are to the touch. Its finely toothed foliage, with a beautiful bright silver-grey colour in winter, turns almost white in summer due to heat and drought. Its pure white umbel flowers dominate the cushion of leaves in spring. This excellent rockery perennial requires little maintenance and weeding thanks to its allelopathic properties*. It can be grown in full sun or partial shade, in light and well-drained soil, alone or mixed with other ground cover plants.

The Achillea umbellata, from the Aster family, is native to mountainous regions of Greece. The plant forms a precious-looking ground cover, growing up to 15-25 cm (6-10in) in flower and 10-15 cm (4-6in) for foliage, depending on growing conditions. It spreads quite slowly on the ground, up to 35 cm (14in), through stolons. Its foliage remains throughout the year, unaffected by winter cold or summer heat. Very finely toothed, covered in a silver-grey that becomes very light in July-August, it has a very soft appearance pleasing to the touch. Flowering occurs from April to early June, depending on the climate. The flower heads are pure white with a creamy yellow centre.

All yarrows thrive in the sun and are incredibly hardy. The Achillea umbellata, requiring very little maintenance, is a small ground cover suitable for rockeries but also for bordering flowerbeds and edging woodland areas under deciduous trees or shrubs, which can tolerate root competition. Non-invasive, very hardy, and not demanding in terms of soil, water-saving, and ideal for dry and arid slopes, this yarrow limits the proliferation of weeds. It adds a precious touch to the garden. It can be combined with other ground cover or cushion plants such as Geranium sanguineum, Erigeron karvinskianus, and Nepeta x faassenii. Many combinations are possible, such as with dwarf Teucrium, Artemisia lanata, Centaurea bella, various Thymus (hirsutus, ciliatus, lanigerus), or other yarrows (millefolium, coarctata, nobilis), etc.

*Certain plants have allelopathic properties: Plants release certain compounds from their roots and leaves that can prevent nearby plants from growing. These compounds can have different purposes, such as killing insects, fighting microbes, or stopping the growth of other plants.