How to grow Convolvulus cneorum

Commonly known as the 'Silver Bush', Convolvulus cneorum is a half-hardy, evergreen shrub native to the coastal regions of Spain, Italy, Croatia and Albania. It is a popular garden plant, which despite is propensity to look quite sickly after its first year in the ground, is widely grown and sold in the south of England. The reason behind it consistent poor performance is quite simply because really isn't suited to the British climate. It is generally too cold, too wet, with not enough heat and not enough sun. That being said under favourable growing conditions Convolvulus cneorum has proven itself to be cold hardy down to -9 C.

How to grow Convolvulus cneorum
When collected from your local plant retailer, Convolvulus cneorum will display a compact, bushy habit with silvery grey foliage. The narrow, lanceolate leaves are actually a dark green colour, the silver quality is the result of a covering of silky, silvery hairs. Once established you can expect Convolvulus cneorum to achieve a height of between 75-100 cm.

Pink buds open to white blooms with yellow throats from May to September. The flowers are somewhat funnel-shaped, 2.5 cm across and borne in terminal clusters.

The prefered time to plant Convolvulus cneorum is during April to May to allow the roots to become established before the onset of winter. It will require a sheltered position (preferably against a south-facing brick wall) open to as much sunlight as possible. In its natural habitat Convolvulus cneorum is often found found growing in within cracks in rocks and so well-drained conditions are an absolute must. Most ordinary garden soils will be fine, just so long as they are well drained. Alkaline soils are best. Do not plant in soils prone to waterlogging. In areas where high rainfalls are expected (in particular over the winter) protect the foliage with panes of glass or perspex, or cover with an open-ended cloche. This retains excellent ventilation, reducing the incidence of fungal infection.

Failure to provide adequate conditions will result in weak growth, dull foliage and quite often root damage due to waterlogged conditions. Poor conditions usually result in the plants failure.

In more northerly climate, consider growing Convolvulus cneorum in a protected alpine house using John Innes No.1.

Main image credit - Valérie Agnès CC BY-SA 3.0,
In text image Simon Eade -

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