Malva arborea aka Tree Mallow

Malva arborea, or tree mallow, belongs to the mallow family. Its native range runs from northwest Europe to the Mediterranean. It is native to Britain and Ireland. The plant grows on sea cliffs and coastal waste ground. It also occurs outside its native range, including California and Oregon. Older sources call it Lavatera arborea. It grows as a biennial or short-lived perennial, often raised as an annual.

Tree mallow grows fast and forms an upright, bushy plant. Garden heights range from 3–6 feet [0.9–1.8 metres]. RHS gives a taller range reaching 8.2 feet [2.5 metres]. Reported spreads range from 3–8.2 feet [0.9–2.5 metres]. Thick stems become woody at the base but can crack. The green leaves feel soft and have toothed edges. They grow around the stems and have five to nine lobes. Some leaves reach 0.75 feet [0.23 metres] long. The plant may keep some foliage through winter.

Pink to purple flowers have dark veins and darker centres. Their cup or funnel shape recalls a small hibiscus. Clusters grow where leaves join the stems. Bloom dates vary between sources and growing regions. NC State reports March to July; Missouri Botanical Garden gives July to September. Plants raised from seed can flower in their first year. Bees gather both nectar and pollen from the blooms. Butterflies and hummingbirds also visit them. Round, flat capsules hold seeds that stay viable for years.

Grow tree mallow in full sun for the most flowers. It also accepts light shade. Give it well-drained soil with moderate moisture. It tolerates drought once established and suits salty coastal sites. RHS accepts acid, neutral, and alkaline soils. Hot, humid summers can make growth difficult. Cool nights suit it better. Missouri Botanical Garden gives overwintering zones of USDA 8–10. RHS rates it H4. Protect plants from cold winds where frost is likely. Tall stems may need support. Remove old flowers to prolong bloom and limit seedlings.

Use it in beds, pots, coastal gardens, or pollinator plantings. The flowers also suit cutting. Self-seeding coastal stands can harm nesting seabirds. Japanese beetles may damage leaves. Rust, leaf spots, and root or stem rot can occur. Young leaves can be eaten raw or cooked. Their dry, hairy texture makes them less pleasant in quantity. PFAF lists no known hazards, but seed edibility remains uncertain. Traditional medicine uses leaf poultices for sprains; this does not establish their effectiveness.