By David Salman, Founder and Chief Horticulturalist of High Country Gardens
From my experience gardening for decades in the challenging conditions of the Intermountain West, I have developed a great appreciation for the genus Achillea (Ä ki lee ä). Here's are a few of their best attributes:
Will grow in most any soil type including clay
Deer and rabbit resistant
Xeric (drought resistant or waterwise)
Long lived growing for a decade or longer when happy
Outstanding cold hardiness
Come in a variety of sizes from groundcovers to large specimens
Add an invaluable architectural element to the landscape with their flat topped flowers
But it is important to know the genus and select the best species and cultivars for your garden. There are great ones and there are weedy garden thugs. I only propagate Yarrow varieties (cultivars) that are sterile and must be grown from cuttings or divisions of the crown. Seed grown cultivars like Achillea filipendulina 'Parker's Gold' (or 'Parker's Variety') and many of the Achillea millifolium types (but not all) will take over their space by vigorously reseeding themselves and crowding out their neighbors.
Here are four of the very best non-seed grown Yarrows that work for most parts of the country:
Moonshine Yarrow (Achillea 'Moonshine') — A nice medium height variety (18" in bloom) with outstanding gray foliage and bright, light yellow flowers. A consistent re-bloomer, deadheading will keep this beauty in flower all summer long. A winning combination when planted with Jupiter's Beard (Centranthus) and taller Beardtongues (Penstemon).
Coronation Gold Yarrow (Achillea filipendulina 'Coronation Gold') — A taller cultivar (30-36" tall in bloom) with gray-green foliage. It is a very upright grower that doesn't flop (as long as it's not grown too wet), 'Coronation Gold' is tough and vigorous enough to pair up Russian Sage (Perovskia) for a long blooming combo.
Red Velvet Yarrow (Achillea millifolium 'Red Velvet') — An improvement on the old standard 'Paprika', 'Red Velvet' holds its deep red color much longer before fading to a pleasing pink. This gives the plant a nice bi-colored look in the garden. It is long-blooming when deadheaded and the foliage has a soft ferny texture. I recommend pairing it with the Old World Sages (Salvia nemerosa cultivars)
Greek Yarrow (Achillea ageratifolia) — A low growing groundcover species with beautiful silver-gray foliage and compact white flowers, Greek Yarrow is very different from the cultivars described above. The foliage is evergreen (ever gray) making it valuable for year-round interest in the waterwise garden. The cheerful white flowers make it an outstanding companion plant for blue flowered Lavender.
Greek Yarrow is a low growing perennial with attractive evergreen, silver foliage and a late spring display of bright white flowers on short stems. An excellent small scale groundcover for planting in hot, sunny conditions. Drought resistant/drought tolerant plant (xeric).
Red Velvet is one of the best with it deep rose-red, flat-topped flower heads that hold their color. Deep green, fine textured foliage, this yarrow is sure to attract butterflies wherever it's planted. Drought resistant/drought tolerant plant (xeric).
Moonshine Yarrow (Achillea Moonshine) is an outstanding perennial plant with silver-gray foliage and lemon-yellow flat-topped flowers that cover the plant all summer. This is a well-behaved variety, meaning it won't reseed and spread.
'Paprika' yarrow is an excellent hybrid variety that blooms with large clusters of bright red flowers surrounding a distinctive yellow eye. The flowers mature to pink creating a beautiful multi-colored effect in the garden. Drought resistant/drought tolerant plant (xeric).