Plant Spotlight: Salvia involucrata ‘Hadspen’
Tender perennials are not for the faint-hearted. They require plenty of patience, some favourable weather conditions, and more than a little bit of attention in order to achieve their potential. But at this time of year, basking in the September sun, they more than justify the effort, and our new favourite half-hardy Salvia involucrata ’Hadspen’ is no exception.
- S. ‘Hadspen’ also has large green ovate-shaped leaves that flush red in cold or excessively dry conditions. As with all members of the Lamiaceae family, their stems are square not round, and in this case dark in colour, in contrast with the flowers and leaves.
It is a tall, graceful perennial growing up to 1.5 metres tall on long, arching, sparsely branched stems that terminate in stunning flowers. So tall are they in fact, that unless they are densely planted with other vigorous perennials that hold each other up, they inevitably need staking to help keep themselves upright when faced with wind and rain.
They are brittle too and long-awaited flowers are all too easily inadvertently snapped clean off the plant when reaching over them to water or deadhead. The sensible thing to do would be to avoid planting them in pots or borders alongside paths or entrances, where they are likely to be brushed past and damaged. But so spectacular are the flowers, the temptation to plant them where you can get up close to admire, is almost always too much to resist.
Like many popular tender perennials, they like heat and sun, and a light free-draining soil. Given lots of water they will grow rapidly in early summer but can sometimes be shy to flower on otherwise healthy-looking plants, producing a profusion of foliage absent of flowers. This is easily rectified by regular applications of high potash plant food at weekly intervals through the growing season.
- S. ‘Hadspen’ is perfect for pots as part of a summer bedding display. We’re growing them on the Terrace with other pink and purple flowered perennials like Verbena boariensis and Osteospermum ‘Tresco Purple’. By the Printing Press we’re growing them in larger tubs with a more muted scheme laced with lots of silver and white in the from of the large-leaved honey flower – Melianthus major – and sweetly scented white-flowered Nemesia.
Their massive stature and brightly coloured flowers also make them a useful component in ‘tropical’ style schemes. We’re trialling them in Walled Garden this year growing alongside other half hardies like the kangaroo apple – Solanum laciniatum – and creeping purple-leaved ornamental sweet potatoes – Ipomoea ‘Sweet Caroline Purple’.
And yet, there’s no reason why S. ‘Hadspen’ couldn’t be grown in more traditional herbaceous borders alongside other better-known perennials. They peak late in the year, so they combine particulary well with other plants that take a while to get going. Dahlias fit the bill, as do ornamental flowering grasses, Crocosmia and Hesperantha.
There are reports of S. ‘Hadspen’ surviving the winter untouched in some warmer parts of the country, but for those of us who garden in less favourable conditions, they must be protected from the cold, or replaced with new plants each spring.
Winter protection is achieved by cutting back plants to about 15 cm, just above a leaf node, after the first frosts have arrived. Plants should then be lifted and packed into crates or pots filled with light compost, and kept dry throughout the winter in a frost fee environment like a greenhouse or conservatory, not unlike overwintering lifted dahlia tubers.
Watering should increase from about March onwards as plants begin to regrow for the following year. However, some insurance can be taken in the form of semi-ripe cuttings taken in late summer. Simply select new growth about 10 cm in length, slightly firm at the base, from non-flowering parts of the plant. Place your cuttings somewhere warm and pot them on once rooted as possible replacements in case your mother plants fail to survive the winter.
Can’t be bothered with the faff? You could try substituting them for pink forms of the hardy fuchsia – Fuchsia magellanica – or indeed, other hardy salvias like Salvia nemerosa ‘Pink Sensation’, which will give you the same exotic look and shocking pink flowers. But in our opinion S. ‘Hadspen’ is the real deal, and nothing makes a splash quite like it.