Santolina rosmarinifolia aka Holy Flax

Santolina rosmarinifolia is a small evergreen shrub in the daisy family. Its common names include holy flax and green lavender cotton. Kew places its native range in western Portugal and western and central Spain. It grows on dry rocks and sandy, stony ground. These sites range from lowlands into the mountains. The plant forms a rounded mound that spreads with age.

Garden plants reach about 1.5–3.3 feet [0.45–1 metre] tall. The RHS describes a compact form around 2 feet [0.6 metre] high. NC State gives an upper height of 3.5 feet [1.07 metres]. Spread ranges from about 1–3.3 feet [0.3–1 metre] across the sources. The green leaves have deep cuts, described as pinnatifid. They give the shrub a fine texture and strong scent. Leaves measure about 1.5 inches long and have no hairs. Slender, smooth green stems carry the flowers above the leaves. Dense yellow flower heads look like small buttons. NC State reports blooms in mid to late spring. The RHS places flowering in summer.

This shrub needs full sun and soil that drains well. It suits hot sites and tolerates drought and dry ground. Sources list sand, loam, chalk, clay, and shallow rocky soils. It accepts acid, neutral, and alkaline soil. The RHS also allows moist soil when drainage remains good. NC State lists USDA zones 6–9; the RHS rates it H5. Growth proceeds at a medium rate. The RHS gives five to ten years to reach full size. NC State notes that the shrub has a short life.

Use it along borders, on slopes, or in small groups. It also suits rock, gravel, coastal, and courtyard gardens. Containers and low edging are further options. It tolerates shearing and can form a low formal hedge. Deer tend to leave it alone. Late-winter or spring pruning helps prevent a loose, woody shape. Semi-ripe cuttings taken in late summer offer one propagation method. Poor drainage can lead to root and crown rot. Pests cause few problems, according to the RHS. Honey fungus may pose a risk, though its severity remains unclear.

Leaves add an olive-like taste to food and drinks. Small amounts can flavour sweet dishes as well. Flowering parts serve as ingredients for herbal tea. Crushed leaves may cause a severe rash on sensitive skin. Dried leaves have uses in scent sachets and potpourri. Extracted oils have uses in perfume. NC State records past insecticide use and treatment of insect bites. Plants For A Future lists no known medicinal use.