Heucherella Onyx

With its splendid glossy foliage of almost black-purple, x Heucherella 'Onyx' is undoubtedly the darkest of the hybrids between heuchera and tiarella currently available. This beautiful new plant, of medium size, forms a dense clump of leaves, from which numerous graceful flowering stems emerge in early summer, reminiscent of those of heucheras, adorned with small white bells. Hardy and tolerant, it is an excellent perennial for partially shaded and cool areas of the garden, in light woodland. It will also make a great statement in a pot on a patio or balcony! 

Heucherella 'Onyx' belongs, like its ancestors heuchera and tiarella, to the Saxifragaceae family. It has inherited the best qualities of these two plants: the spectacular foliage of heuchera and the abundant flowering and superior robustness of tiarella. It is an evergreen to semi-evergreen perennial, growing in a low and compact clump. At maturity, it reaches 25cm (10in) in height (for the foliage), 40cm (16in) in flower, and 40cm (16in) in width. The leaves measure 5 to 10cm (2 to 4in) in diameter. The leaves that emerge in spring are narrower. They give way to larger, rather round leaves, strongly lobed at the edges, with prominent veins. They are dark purple on the upper side, and purple on the underside. The lamina has a beautiful satin appearance that enhances the depth of the colour. The very long-lasting flowers appear in June-July, grouped in condensed spikes, carried by thin and hairy stems that are 40cm (16in) tall. This white flowering with tiny bells gives an impression of foam.

Heucherella 'Onyx' appreciates wooded environments with a humid atmosphere. It is less sensitive than heuchera to the combination of heat and humidity. It naturally finds its place in moist woodland alongside ferns, Impatiens balfouri, Solomon's seal, and astilbe. It is also a good border plant to surround hydrangeas and camellias, for perennial beds, or in a rockery. Keep it away from the blazing sun. It can also be used as a waterside plant. It will thrive in containers or sheltered gardens away from direct sunlight. It should be planted in well-drained compost without excessive fertilisers. Water in summer. Reduce watering in winter. Pots will need protection against cold winter winds.