Common Name: lithodora
Type: Herbaceous perennial
Family: Boraginaceae
Native Range: Northwestern France to southwestern Europe
Zone: 6 to 8
Height: 0.50 to 1.00 feet
Spread: 2.00 to 25.00 feet
Bloom Time: May to June
Bloom Description: Blue
Sun: Full sun to part shade
Water: Medium
Maintenance: Medium
Suggested Use: Ground Cover
Flower: Showy
Culture
Best grown in humusy, moist, fertile, acidic, very well-drained soils in full sun to part 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. Tends to do poorly in climates with hot, humid summers. 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. The main flowering period is late spring to early summer with minor, sporadic additional bloom to fall. 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.
Problems
No frequently occurring insect or disease problems. Damping off is its primary disease problem. Watch for aphids.
Uses
Ground cover. Specimen or accent for borders or rock gardens. Edger. Spill over walls.