the many different types of the yarrow (Achillea) is popular not only with the woolly quadrupeds, to whom they owe its name. Gardeners also love the robust, versatile perennial whose more than 100 different species are native to Europe and West Asia. The botanical name Achillea can be traced back to Achilles who, according to legend, supplied his wounds with the medicinal plant.
The plant belongs to the family of composite flowers (Asteraceae) and includes species with growth heights between 10 (Achillea umbellata) and 150 centimetres (Achillea filipendulina). The growth habit varies from species to species. So there are some that grow obstinate, others form dense cushions, and still others tend to proliferate and quickly colonize larger areas.
The finely pinnate leaves alternate on the tightly upright stalks. They gave their species name “millefolium” (thousand-leaved) to the common yarrow, as it seems that they are composed of innumerable small leaves. The leaves are alternately arranged and usually cut once or several times. Rather rarely one finds also whole-edged leaves. Depending on the species, the foliage is sometimes grey-green, sometimes green and slightly hairy. Some varieties also have an aromatic scent.
Yarrow flowers in many different colours from delicate pink to bright pink and strong carmine red. Very attractive are also the multicoloured Achillea-Filipendulina hybrids like ‘Tierra del Fuego’ or ‘Terracotta’. While the flowers of the common yarrow are creamy white, the gold yarrow, whose hybrids are also called yarrow, lives up to its name and shines in intense yellow tones. Especially popular here are the two bright yellow varieties ‘Credo’ and ‘Coronation Gold’, which are considered to be very stable. What they all have in common, however, is the flower shape: numerous, tiny individual flowers form the striking pseudo umbels. The individual flowers consist of small ray flowers, which can be differently coloured. In their middle are tiny disc-shaped flowers, which are usually yellow in all species and varieties. The flowers appear in June and flower in many varieties even into September. They mainly exude an aromatic scent that magically attracts bees and other insects.
After flowering, yarrows form inconspicuous yellowish to greyish fruits containing the tiny brown seeds.
The yarrow does not make high demands on its location, but for all species a sunny location in the areas of the bed and open space is ideal.
Yarrow prefers a permeable, light, sandy soil, which can be rich in nutrients. Especially the species with grey foliage need such a good drainage, because they prefer it dry. The green-leaved species can also cope with more humid soils.
Since most yarrow prefer nutrient-rich, permeable soils, you should improve lean soils with some compost before planting them, and loosen up heavy loamy soils with sand or gravel. The best planting times for yarrow are – as for most perennials – spring and autumn. Before planting, the root balls are dipped, i.e. held in a bucket of water until no more air bubbles rise. Even after planting the perennials, the water is once again penetrating. This ensures that the freshly planted root ball and the surrounding soil connect more quickly.
In the garden, yarrow is not exactly one of the most durable shrubs; after about five years it is usually over. Unless you divide the plants regularly every three to four years. The best period for this is spring after budding or early autumn immediately after flowering. Here the eyrie is cut out root-deep and the piece to be divided is levered out of the planting hole with the spade. Then divide the root ball into two pieces with the spade. When replanting, add a handful of horn shavings to the planting hole to make it easier for the plants to grow. After insertion, the yarrow must be watered well and denser flower plates can be achieved by cutting out weak shoots. If you remove withered umbels in good time, they will usually bloom again. Fertilizing is usually not necessary. On the contrary, the stability of millefolium hybrids can even suffer on soils rich in nutrients. Species that prefer a nutrient-rich soil can, however, start the new season in the spring with a composting dose. You only need to water your yarrow regularly directly after planting. Otherwise, most species and varieties cope better with dry soils than with humid ones. Waterlogging should be avoided at all costs, as it can lead to root rot.
The yarrow can be cut back to its base in autumn. However, as their flower umbels are very stable and produce beautiful pictures in the bed, it is worth leaving them standing over the winter and only reaching for the garden shears shortly before new shoots.
The type of use depends on the growth height. While the local common yarrow mainly decorates natural gardens, gold yarrow and fine yarrow (Achillea-Millefolium and Filipendulina hybrids) are the perfect partners for many sun-loving perennials and are particularly well suited for individual use. Beautiful contrasts form plants with other flower forms, for example purple coneflower (Echinacea), sage (Salvia) or globe thistle (Echinops), and ornamental grasses. The low species are suitable for use in rock gardens as well as for troughs and bowls. Especially the high species of yarrow are good cut flowers, but they can also be used for the production of dry bouquets. Yarrow has been used as a medicinal plant for centuries and has an analgesic effect.
Species and varieties
The common yarrow (Achillea millefolium) and the gold yarrow (Achillea filipendulina) are particularly interesting from a horticultural point of view. Rarely, however, the respective species find use in the gardens, rather it is the hybrids. A distinction is made between the multi-coloured Millefolium hybrids and the revolutionary Filipendulina hybrids. In order to understand the difference, it is best to think about a meadow grazed by sheep. The common yarrow, which is appreciated in folk medicine, got its name because it is eaten so gladly by sheep. Its ability to drift through again after the browsing is also used in the garden, as it blooms a second time after being pruned back – and that into the autumn.
Another survival strategy of the common yarrow is its proliferation. If you have the space to let them hike, unplanned beautiful combinations can result. In contrast, the goldarbe and their hybrids, which are still known from farmer’s gardens, grow rather obstreperously. For this reason they are very popular with gardeners and are now part of the standard range of perennial gardeners. Some of the best-known Filipendulina hybrids come from the breeding of Ernst Pagels, a famous yarrow breeder from East Frisia, who discovered a novelty in his nursery by chance in the 1990s. The yellow bed shrub classic Achillea filipendulina had crossed with wild forms on a neighbouring field. In the meantime, this discovery has given rise to a new generation of Filipendulina hybrids that have been flowering for a long time, are stable and do not proliferate, for example the red-orange ‘Walter Funke’ or ‘Terracotta’, whose colour lives up to its name.
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Yarrow can be propagated both by division and by sowing. Especially with hybrids, however, the seedlings are rarely true to the variety.
Diseases and pests
The yarrow is a very robust plant. Occasionally, they can be attacked by real and false mildew or rust. If the location is too damp, snails can also become a problem, so you should make heavy soils with some gravel more permeable.
I am Don Burke, one of the authors at My Garden Guide. I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.