Details
 
P. vialii is a rosette-forming herbaceous perennial to 40cm, with hairy, oblong-lanceolate leaves and erect stems with a terminal conical spike of light violet flowers 1cm in width, opening from red buds
 
 
 
Hardiness
 
H5 - Hardy in most places throughout the UK even in severe winters (-15 to -10)
 
 
 
Sunlight
 
Full Sun, Partial Shade
 
 
 
Aspect
 
South-facing, North-facing, West-facing or East-facing
 
 
 
Exposure
 
Exposed or Sheltered
 
 
 
Moisture
 
Moist but well-drained
 
 
 
Soil
 
Chalk, Clay, Sand, Loam
 
 
 
pH
 
Acid, Alkaline, Neutral
 
 
 
Size
 
Ultimate height: 0.1-0.5 metres
 
Ultimate spread: 0-0.1 metre
 
Time to ultimate height: 2-5 years
 
 
 
How to grow
 
Cultivation
 
Grow as biennials for bedding and in a container or rock garden. Favours a sheltered position in sun or partial shade
 
 
 
Propagation
 
Propagate by seed or root basal cuttings
 
 
 
Suggested planting locations and garden types
 
Flower borders and beds Low Maintenance Cottage & Informal Garden Wildflower meadow Wildlife Gardens
 
 
 
How to care
 
Pruning
 
No pruning required
 
 
 
Pests
 
May be attacked by aphids, vine weevil, slugs, leaf and bud eelworms and glasshouse red spider mite
 
 
 
Diseases
 
May be subject to a leaf spot and grey mould
 
 
 
Source: www.rhs.org.uk