Agastache nepetoides Fuji no Yuki

The Agastache nepetoides, commonly known as the giant hyssop in the United States, is a rather rare giant species in European gardens despite its ease of cultivation. This perennial forms a quite spectacular clump in perennial borders, large rockeries, and finds its place in naturalistic settings. It will be appreciated for its long summer to autumn flowering in thin and dense spikes, ranging from chartreuse yellow to whitish, highly visited by bees and other pollinators. Less aromatic than other agastaches, its large slightly hairy leaves are quite decorative. Undemanding, robust, and very hardy, this species enjoys full sun to partial shade and well-drained, moist to drier soils. Short-lived, it readily self-seeds in light soil.

Agastache nepetoides belongs to the Lamiaceae family, it is a cousin of mints and salvias. It is a large deciduous herbaceous plant, perennial from its stump, with above-ground vegetation that disappears in winter. It is native to North America (Connecticut, Vermont, Pennsylvania, Missouri etc.), where it is occasionally found in clearings, at the foot of cliffs, on forest edges, on slopes and rocky areas. It particularly thrives in damp groves, fields, or roadside locations, in habitats disturbed by human activity. This species adapts to various soils, but prefers well-drained ones. 

The plant forms an upright clump that can exceed 1.50 m (5ft) in height, supported by square and hairy stems with rather triangular leaves, 10-15 cm (4-6in) long, coarsely toothed at the edges, hairy on the underside, dark green in colour. The leaves are paired at each node on the stems. When crushed, they release a light menthol scent. The leaves located at the top of the stems are smaller. Flowering occurs from July to October, and continues until the first frosts. At the end of the branched floral stems, cylindrical and elongated clusters appear, measuring up to 6 cm (2in) long. Each cluster is composed of numerous small flowers with 5 petals and prominent stamens tightly packed together. The flowers open in a yellow-green colour and gradually turn to an uncertain white tone. After pollination by insects, the flowers give way to small fruits, 1.5 to 2 mm (1in) long, which do not open at maturity.

In a slightly wild area of the garden, or in a large rockery, combine this tall agastache with Schizachyrium scoparium 'Blue Heaven', Galega, catchflies, 'Buenos Aires verbena, tall yarrows, Helianthus salicifolius, or H. decapetalus 'Plenus', for example, as they are equally robust plants that have their place in a garden that makes room for nature. Echinaceas as well as tall mulleins will also be lovely companions for this quite spectacular plant.