Achillea maritima aka Cottonweed

Achillea maritima stays green all year and lives for many years. It has a low, shrubby form. It belongs to the daisy family, Asteraceae. People call it cottonweed, sea cottonweed, and sea cudweed. Its native range runs from western Europe to the Mediterranean and Caucasus. It grows wild on Gran Canaria and Lanzarote too. The RHS lists it as native to Britain and Ireland. Its old names include Diotis candidissima, Filago maritima, and Otanthus maritimus.

This bushy plant grows about 0.3–1.6 feet [0.1–0.5 metres] tall. Its spread at full size falls within that same range. It takes two to five years to reach full size. Small, oblong leaves give it a fine texture. These leaves have a woolly coat that looks like silver. They stay green and have a strong herbal scent. Crush the leaves to make their scent stronger. Its low form and lasting leaves add interest when no flowers bloom.

Yellow flower heads bloom from June to September. Each head spans about 0.03 feet [0.008–0.01 metres]. The flowers have a scent too. They add summer colour above the silver leaves. The plant keeps blooming into early autumn. Both its flowers and leaves give the plant its scent. The small flower heads contrast with the leaves' soft look.

Give cottonweed full sun and soil that drains well. The RHS lists sand and loam as soils that suit it. It grows in acid, neutral, or alkaline soil. Moist soil suits it too, as long as it drains well. Choose a site that faces south or west to meet its needs. It can grow in spots with or without shelter. Wind and salt spray do not rule out sites near the coast. The RHS gives it a hardiness rating of H5. This covers winter lows of about −15 to −10°C. The rating applies to growing conditions in the United Kingdom.

Cottonweed suits gardens near the coast, cottage gardens, and informal planting. The RHS lists it for wildlife gardens too. Its compact form fits spaces that need a low plant. Its green leaves last through winter. The listed way to grow new plants is from seed. It needs no routine pruning. The RHS reports few usual pest or disease problems. These traits keep its stated care needs quite simple. Sun and good soil drainage remain key when choosing a site.