Lithodora diffusa 'Grace Ward'
Common Name: lithodora
Type: Herbaceous perennial
Family: Boraginaceae
Zone: 6 to 8
Height: 0.50 to 1.00 feet
Spread: 2.00 to 2.50 feet
Bloom Time: May to August
Bloom Description: Blue
Sun: Full sun to part shade
Water: Medium
Maintenance: Medium
Suggested Use: Ground Cover, Naturalize
Flower: Showy

Culture

Best grown in humusy, moist, fertile, acidic, well-drained soils in light to moderate shade. Tolerates full sun in cool summer climates, but appreciates some part shade at the heat of the day in hot summer climates. Soils should not be allowed to dry out. Thrives in Mediterranean-type climates on slopes or raised beds. Generally dislikes the hot and humid conditions of the deep South. Apply a winter mulch in the northern parts of the growing range.

Noteworthy Characteristics

Lithodora diffusa, commonly known as lithodora, is a prostrate, multi-branched ground cover which typically grows to 6-10” tall but spreads over time to 24-30” wide. It is native to scrubby areas and woodland margins from southwestern Europe along the Mediterranean to Turkey and south to Morocco.

Tiny, 5-petaled, funnel-shaped flowers (to 1/2” wide) are an intense blue with slightly darker reddish purple stripes. Flowers bloom from late spring to early/mid-summer (May to early August), sometimes with minor sporadic additional bloom to fall. Woody prostrate branches are densely clad with narrow, sessile leaves (1/2 to 1” long by 1/4” wide) which are dark green above and gray-green beneath. Leaves and stems are hairy. Leaves remain evergreen in warm winter climates.

Synonymous with Lithospermum diffusum.

Genus name comes from the Greek word lythos meaning stone and dorea meaning a gift, presumably in reference to growing habitat in the wild.

Specific epithet is in reference to the diffuse or spreading plant habit.

‘Grace Ward’ is a vigorous popular cultivar featuring deep blue flowers on woody prostrate branches clad with dark green leaves. Differences between this cultivar and the straight species are often minor.

Problems

No frequently occurring insect or disease problems. Damping off is its primary disease problem. Watch for aphids.

Garden Uses

Ground cover. Specimen or accent for borders or rock gardens. Edger. Spill over walls.