By Miranda Kimberley Friday, 07 June 2013
These unfussy growers produce a mass of small stems and whorls of leaves, Miranda Kimberley finds.
The genus Veronicastrum includes plants that create a strong vertical silhouette at the back of a flower border. They are a green mass of tall stiff stems, surrounded by whorls of leaves, and they peak with long flower spikes from summer to early autumn in shades of white, blue, pink and purple. They are unfussy growers, only insisting on fertile soil, but once established they are trouble-free.
The main species in cultivation is V. virginicum. This is a native of the USA, where it grows as a wild flower and is also cultivated. Many choice cultivars have been bred from this species, including the lavender-blue flowered 'Fascination' and 'Lavendelturm' as well as pinks such as 'Erica'. There are a few other species grown in the UK, including the Siberian species V. sibiricum, from which the variety 'Red Arrows' was derived.
All Veronicastrum have a strong, upright growth, with their heights ranging from 1m up to 1.8m. The inflorescence is made up of slender and spike-like racemes, sometimes described as candelabra because there is usually one main flower spike surrounded by smaller side spikes.
The stamens are densely packed and protrude in a brush-like fashion perpendicular to the raceme. The foliage of Veronicastrum is also very attractive. Whorls are formed around the stems, made up of three-to-seven leaves, which are lanceolate and slightly serrated.
They need a position in moist, fertile soil, in sun or partial shade. They grow so erectly that they do not always need staking but if cautious or in an exposed position do so. They have a habit of seeding around but this is easily rectified or encouraged. The best method of propagation is by division in early spring, but this can also be carried out in the autumn. Softwood and semi-ripe cuttings can be taken in the summer and seed collected and sown in the autumn.
Veronicastrum are best planted at the back of a mixed herbaceous border because of their stature. They also suit naturalistic planting schemes, with prairie style plants. They have been used to great effect in the Piet Oudolf borders at RHS Wisley, leading down to the Great Glasshouse. There they form large clumps against grasses including Calamagrostis (approx equal to) acutilora 'Karl Foerster', Salvia (approx equal to) superba 'Dear Anja', Sedum telephium 'Matrona', Phlomis tubersoa 'Amazone' Award of Garden Merit and Trifolium rubens.
They are also a great addition to wildlife gardens because they are a magnet for bees. For those who find these little facts interesting, the genus is named for Saint Veronica, who in Christian mythology gave Christ her veil to wipe his forehead while carrying the cross.
What the specialists say
- David Ward, nursery manager, Beth Chatto Gardens, Essex
"Veronicastrum is an excellent genus. It's full of hardy, trouble-free plants that suit fertile soil in the sun. All the varieties are rather nice. My personal favourites include 'Lavendelturm', which has soft purple-mauve flowers that seem to glow in dull light. I also like new variety 'Erica', which has dark purple-red shoots in the spring.
"They provide vertical structure to a border, reaching about 4-5ft tall, but they don't usually need to be staked. You can also Chelsea chop them in late May to provide a shorter, sturdier plant. Once established they do very well - we have some clumps that are around 15-20 years old. The only slight issue to watch out for is seeding around, and shoots can occasionally get fasciated, but this can be an interesting feature."
- Claire Austin, owner, Claire Austin Hardy Plants, Powys
"Veronicastrum is an elegant group of plants. The tallest are ideal for the back of a border, while the few shorter ones can add see-through glamour to the middle of the border.
"The species or varieties that stand out for me are V. virginicum f. roseum 'Pink Glow', 'Fascination' and 'Album'. 'Pink Glow' has long spikes of delicate pink flowers. It's a graceful variety with long, mid-green leaves.
"These plants do need a soil that does not dry out, especially in summer. Otherwise, I have experienced no problems with this lovely group of plants."
- Jessica Potter, mail order manager, Cotswold Garden Flowers, Evesham
"These are fantastically hardy and very tolerant plants. They are in the family Scrophulariaceae and they have similarities to Veronica. Their main benefit is that they add height, structure and texture to the garden. They also attract bees and butterflies, which is a bonus.
"They tolerate sun to dappled shade and like well-drained soil. The only downfall is that they can suffer with mildew should they become too dry. Propagation can be achieved easily by dividing or taking cuttings in the spring when the plants have begun to show.
"V. virginicum 'Album' is a great plant, with graceful white flower spires topping dark-bronze stems. In the ideal position they can get as tall as 6ft. It flowers in midsummer and can have a second flush in autumn."
- David Anderson, general manager, Seven Hills Garden Centre
"I adore this understated herbaceous perennial. Its tall spires of flowers make an aggressive and commanding statement to any herbaceous border.
"We sell 'Lavandelturm', 'Fascination' and 'Album'. These three give us a spectrum of white and light to dark purple. We sell these only in three-litre pots as their height can be a bit of a pain in smaller pots when its windy. There's nothing more frustrating and down-heartening to see our planterias battered by the wind and all the tall specimens thrown to the floor in devastating fashion.
"The branching spires of tubular flowers appear from July to September above whorls of deep-green leaves. It is an excellent plant for adding impact in the garden towards the end of summer. The flowers associate well with prairie style planting and also add height to the back of a sunny or partially shady border.
"This plant is a monster in the herbaceous world, so we display them with an under planting of carex or any other medium-tall grasses. Another display idea is to use the candelabra-like effect flowers of Veronicastrum as a simple backdrop in the corners of your display garden. Their long-lasting flowering time means you can leave them there for quite a long while."
Species and varieties
- V. 'Adoration' is a particularly upright form, producing lilac-pink flower spires in midsummer. It is an elegant, long-flowering plant. Height: 1.2m.
- V. latifolium produces white flower spikes with purple filaments, and red autumn foliage. Height: 1m.
- V. sibiricum is a smaller plant than virginicum. It produces larger, coarser leaves, with deeper venations. The flowers spikes are stubbier than its relative, with dense lavender flowers sometimes giving a hint of pink. Height: 1.2m.
- V. sibiricum 'Red Arrows' is so named because its buds are deep pink and the side flowers open at the same time as the main flower, creating an arrow shape. Once open, however, the flowers are lilac. Height: 1.2m.
- V. virginicum is the most commonly grown species and it has produced many excellent cultivars. It has an erect habit with dark-green whorls of leaves. Elegant, slim spires of pink flowers are produced in late summer. Height: 1.6m.
- V. virginicum 'Album' is a great white form with slender spires in July and August. Height: 1.4-1.8m.
- V. virginicum 'Apollo' bears long spikes of lilac-blue flowers in mid to late summer, topped with green buds that bend and curve. A robust plant with strong stems. Height: 1.8m.
- V. virginicum 'Erica' produces long, slender spires of red buds, which open to tiny pale-pink flowers in mid to late summer. Nice whorls of dark-green leaves. Height: 1.2m.
- V. virginicum 'Fascination' produces dense, slender, branched spikes of small lavender-blue flowers between July and August. It does well even in dry shade. Height: 1.2-1.8m.
- V. virginicum 'Lavendelturm' is a highly attractive variety with strong stems and long spires of pale-lavender flowers. Height: 1.5-1.8m.
- V. virginicum f. roseum 'Pink Glow' has pale-pink almost white tubular flowers from July to September. The whorled leaves are deep green. Copes with partial shade. Height: 1.5m.
- V. virginicum 'Temptation' has strong, upright stems bearing slender, dense racemes of tubular, purple-pink flowers in summer. Height: 1.75m.
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