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Lithodora diffusa Grace Ward


Purple gromwell

Great rock garden plant

A low-growing evergreen shrub, forming a loose mat of wiry stems clothed in dark green, evergreen leaves. Plants may be compact at first, becoming more trailing as they mature. In late spring and early summer small, star-shaped, intense blue flowers embroider the plant with jewel-like effect. 


Anywhere in full sun. Perfect tumbling over walls, rocks, alongside paving or in gravel, or in shallow planters.


A well-drained acidic soil. No maintenance required. Older plants may be trimmed after flowering to promote compact growth.

Also known as lithospermum, this plant is often mistaken for a gentian due to the intense colour of the flowers.

Plant details

In depth plant information

Property Value
Plant type Ornamental shrub
Flower colour
Foliage colour
Typically available April - September
Season of interest Spring, Summer
Flowering March - August
Evergreen Yes
Plant height 10 cm - 50 cm
Plant width 10 cm - 50 cm
Fragrant flowers No
Hazardous No
Attracts bees No
Attracts butterflies No
Plant height in 5 years 50 cm
Medicinal No
Hardiness zone (?) H5

Will perform best in these conditions

Property Value
Soil type Sand, Loam
Light exposure Full sun
Soil drainage Well drained
Planting instructions

Water the plant in its pot thoroughly before planting – give it a good soaking. Prepare the area by digging a hole twice the size of the pot. Dig compost into the base of the hole. Remove the pot and position the plant in the hole, with the top of the rootball about level with the surrounding soil. Refill the planting hole with a mixture of garden soil and compost, firming as you go. Water in well and keep well watered during the plant's first year.

Planting site Flower border and beds, Banks and slopes, Gravel garden, Rock garden

Typically available

From April to September