Malva subovata aka Sea Mallow

Malva subovata is a fast-growing semi-evergreen subshrub that typically reaches 1-1.5 metres (3-5 feet) in height with a spread of 0.5-1 metre (2-3 feet). In ideal conditions, some specimens can grow larger. The plant has a bushy, upright habit with woody stems and reaches its mature size within 2-5 years. Note that it is relatively short-lived, typically lasting around 5 years, but self-seeds readily to maintain its presence in the garden.

Malva subovata is native to the shores of the western and central Mediterranean region, including coastal areas of southwestern Europe and North Africa. Its native range encompasses Portugal, Spain, France, Corsica, and North African coastal regions. The species has also naturalized in parts of Western Australia, Baja California (Mexico), and Israel. It is well-adapted to Mediterranean climates with hot, dry summers and mild, wet winters.

Malva subovata is frost-hardy but sensitive to severe cold. It tolerates light frosts down to about -5°C to -7°C (19-23°F), corresponding to RHS hardiness rating H3 and USDA zones 9-11. In colder climates, it benefits from a sheltered position away from cold, drying winds and may need winter protection. The plant can also be grown in containers and overwintered in an unheated greenhouse where temperatures are not reliably mild.

Malva subovata is adapted to Mediterranean coastal conditions and tolerates a range of humidity levels. It is notably tolerant of salt spray and maritime conditions, making it excellent for coastal gardens. The plant prefers good air circulation and may be susceptible to fungal issues in overly humid, stagnant conditions. It thrives in the relatively dry air of Mediterranean-type climates but adapts to average garden humidity when drainage is good.

Malva subovata has modest fertilizer requirements and thrives in average, even poor soils. An annual mulch with well-rotted manure or compost in spring provides sufficient nutrients for healthy growth. Avoid over-fertilizing, as rich soils can promote excessive soft growth at the expense of flowers and may reduce the plant's drought tolerance. In containers, a balanced slow-release fertilizer applied in spring is adequate.

Malva subovata produces beautiful hibiscus-like flowers from late summer to mid-autumn, with some sources reporting blooms from April through October in favorable conditions. The flowers are large, up to 7cm (3 inches) wide, in shades of pale lavender, pink, or lilac-pink with distinctive purple-magenta veins and a dark purple eye at the center. They appear on upright stems above the grey-green foliage and attract bees and butterflies. Deadheading spent flowers encourages continued blooming.

Malva subovata is primarily an outdoor garden plant, thriving in USDA zones 9-11 (RHS H3). In mild coastal areas of the UK, it grows outdoors year-round. In colder regions, plant it in a sheltered, sunny spot protected from cold winds, or grow in containers that can be moved to an unheated greenhouse for winter. It tolerates salt spray, making it ideal for seaside gardens.

Malva subovata benefits from annual pruning to maintain shape and vigor. RHS recommends Pruning Group 6, which means cutting back growth in autumn after flowering has finished. This typically involves cutting stems back hard to encourage fresh growth the following spring. BBC Gardeners' World suggests pruning in October-November. Additionally, deadheading spent flowers throughout the blooming season extends the flowering period and keeps the plant looking tidy.

Malva subovata can be propagated by seeds or cuttings. For seed propagation, sow seeds in spring after the last frost at a depth of about 6mm (¼ inch), spacing them 30-45cm (12-18 inches) apart. Germination typically occurs within 7-14 days. For cuttings, take softwood cuttings in spring, ensuring each cutting has at least one node. Apply rooting hormone and plant in well-draining medium; roots should develop within 2-3 weeks. The plant also self-seeds readily in the garden.

Malva subovata is generally pest-free, making it a low-maintenance choice. However, it can be susceptible to several fungal diseases including stem rot, soil-borne fungal infections, and rust. Good drainage is essential to prevent these issues, as the plant is particularly vulnerable to problems caused by excess winter wet. Ensure adequate air circulation around plants and avoid overwatering to minimize disease risk. Remove any affected growth promptly.

Malva subovata is pollinated by insects, particularly bees and butterflies. The large, showy flowers with their purple veining and dark eye serve as nectar guides to attract pollinators. BBC Gardeners' World notes the plant has 'nectar/pollen rich flowers' that make it valuable for wildlife gardens. The RHS recognizes it as an excellent pollinator plant, and it has received their Award of Garden Merit partly for its wildlife value.

The most commonly available variety is Malva subovata 'Bicolor' (syn. Lavatera maritima 'Bicolor'), which features the characteristic pale lavender flowers with purple veining and dark eye. Another notable selection is 'Princesse de Ligne', a French cultivar. All varieties share the species' grey-green felty foliage and shrubby growth habit. When the species was classified as Lavatera maritima, it received the RHS Award of Garden Merit.