Lithodora oleifolia

Lithodora oleifolia, also known as Olive-leaved Gromwell, is much less known than its acid-loving cousin, Lithodora diffusa, widely available in the horticultural trade. it is a rare and beautiful botanical species, well-suited to limestone and dry soils, with large pale blue-violet flowers that seem to echo the pure and vibrant sky of its native Catalonia. This prostrate undershrub also has very attractive silver foliage, actually dark green but with shiny bristles. Give it what it needs in the garden: sun, warm and rocky slopes, and no water all summer long. 

The Olive-leaved Gromwell, also known as Lithospermum oleifolium, is a plant of the borage family, endemic to Catalonia and the Eastern Pyrenees. It is found particularly in Spain, in a small station near Figueras, growing in the cracks of limestone rocks. It is a slow-growing woody undershrub with a spreading habit, almost prostrate. At maturity, after 5 to 10 years of cultivation, it will reach a height of 20 to 30 cm (7.9 to 11.8 in) with a spread of 40 to 80 cm (15.7 to 31.5 in), sometimes more. The slender, highly branched stems, lying on the ground, bear persistent leaves arranged in clusters at the ends of the branches. They are ovate, pointed, dark green on the upper side, with silky and whitish undersides. Flowering takes place in spring or early summer, April-May-June depending on the climate and weather. The large, slightly violet-blue flowers, are enclosed in a woolly outer corolla and grouped in very short clusters, or even solitary. The seeds are as hard as stones, and the origin of the Latin name Lithospermum, which literally means "stone seed".

While blue flowers are always sought after, gromwell flowers are passionately sought after because they are both shiny and delicate. Lithodora oleifolia is perfect in a dry garden, a limestone rockery, or a raised bed enriched with gravel. Particularly well-adapted to a Mediterranean-type climate, it can go without watering in the summer once established. Its hardiness, from -12 to -15°C (10.4 to 5 °F) in well-drained soil, allows it to be adopted in many regions where cistus, lavender, rosemary, and similar plants thrive. For example, it can be associated with Amorpha canescens, Lupinus chamissonis (a small lupin from semi-arid areas), or nepetas in a blue garden. Some touches of colour can be added by associating it with Montpellier soapwort (pink), creeping baby's breath (white or pale pink), Teucrium cossonii (red), or the lovely orange Mimulus aurantiacus.