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Agastache, or giant hyssop.Larry Davidson

Agastache, or giant hyssop, was once a plant completely ignored by gardeners. It was just too wild and woolly in both texture and behaviour. But its long slender stalks and incredible scent make it a magnet for butterflies, hummingbirds and plant breeders.

Any graceful, spiky plant deserves a prime place in a summer border. The specimen pictured here is 'Kudos Coral' but there's also Yellow, Mandarin, Gold and Silver Blue options. They are hardy perennials if you are in Zone 5 or warmer, and promise months of colour, shorter stalks that remain upright and an unbelievably delicious aroma.

To help them thrive, find a sunny spot for planting. They can put up with a baking hot site and will not be discouraged by a bit of drought. But they must be in an area where they won't get wet during the winter. Normal, classic planting will help, especially well-drained soil full of organic matter. To check the drainage, pour water into the hole and make sure it disappears quickly. Press down to get rid of remaining air pockets. And always dress perennials for the weather by adding a bit of compost around the soil at the surface.

Larry Davidson of Lost Horizons assures me that on his own exposed site in the windy highlands of Ontario, the agastache survived in perfect condition after one of the worst winters in decades. "They have amazing fragrant foliage," he says, "and look great combined with some of the new echinacea colours."

The new series of hyssop are much shorter (between 45 cm and 50 cm). Buy them in threes so they have instant impact and let them mature for a season. After that, you will have them forever.

Find Agaststache 'Kudos Coral' at Lost Horizons in Acton, Ont., where it retails for $11.