By late July, the Yunnan meadow rue (T. delavayi) starts to show not the typical fluffy mass of stamens, but instead small flowers composed of four or five lilac sepals backing a tuft of cream-coloured stamens. Held on spreading, interlaced branches, the hundreds of blooms create what the late English horticultural artist, author and garden designer Graham Stuart Thomas called "a great pyramidal airy-fairy display." Because the plant reaches two metres tall, you may have to look up to see the down-facing flowers floating against the sky. We never stake this strong-stemmed perennial, but a few sticks and twine might be needed in windy sites to keep the flowers aloft. Given a choice of just one meadow rue, this might be it. But it would be a toss-up with the slightly later cultivar 'Hewitt's Double', its tiny, perfectly round flowers strung like beads along thin stems, giving the impression of a tall, lilac-coloured baby's breath, showy and ethereal all at the same time. Like other meadow rues, 'Hewitt's Double', which reaches 1.3 metres tall in due course, emerges from the ground quite late in spring: mark the spot, be patient and don't dig around looking for growth or you'll snap emerging new shoots. Similar to the Yunnan meadow rue in height and flower form is T. rochebruneanum, a showy late-blooming species with strong stems that seldom need a prop.
Look up, way up - next in the meadow rue parade is a stilt-walker. New for us, and the tallest perennial we grow, is T. 'Elin', topping out at more than three metres, yet still managing to give a light, airy impression. Purple-hued stems hold scores of small, pale mauve buds that open to reveal greenish white stamens, giving an overall effect of a creamy cloud. The subtle colour shows up best against the dark backdrop of a hedge or shrub. Where breezes blow freely, several very long bamboo canes and a couple of levels of twine will help steady this long-legged plant, which could tower behind phlox, shasta daisies, tall lilies or daylilies.
Start right: Soil and site
If phlox, sneezeweed or monkshood thrive in your garden, meadow rues will likely do just fine. Though not fussy about soil, these plants don't care to be bone-dry for extended periods or bogged down with water. Damp but well-drained says it all. Best is loamy earth liberally enriched with organic matter in the form of compost or thoroughly decayed leaves, along with well-rotted manure and some peat or coir. A mulch at least five centimetres thick of any organic material, from compost to grass clippings, will help hold moisture. In times of drought, a thorough soaking every seven to 10 days should suffice - provided you've prepared the soil at the start. Light, flickering shade is a meadow rue's idea of perfect exposure, but we grow them in full sun, as well as on the north side of - well, practically underneath - an expansive Preston lilac.