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Althaea officinalis

marsh mallow

Malvaceae

Europe, western Asia, and North Africa

Attracts Pollinators Attracts Butterflies

SunFull Sun – Part Shade

WaterHigh

HardinessZones 3–9

Overview

Althaea officinalis, marsh mallow, is an erect herbaceous perennial in the mallow family (Malvaceae) reaching 39-79 inches (1-2 m) tall on stout, softly hairy stems. The whole plant is covered in dense, velvety grey-green down, and the leaves are broadly oval to triangular, 2-4 inches (5-10 cm) long, with shallow lobes and toothed edges. From July to September pale pink five-petalled flowers 1-2 inches (2.5-5 cm) across open in clusters from the upper leaf axils, each with a central column of fused stamens typical of the family. Flat, disc-shaped fruits follow, breaking into many one-seeded segments. It grows in damp, brackish ground on the upper edges of salt marshes, ditches, and tidal riverbanks, tolerating both salt and seasonal flooding. The thick, mucilage-rich roots were the original source of the marshmallow confection and have a long record of use in herbal medicine. It dies back to a woody crown each winter and reshoots in spring, spreading slowly into clumps. One limitation is its preference for consistently moist ground, so it struggles in dry borders.

Native Range

Althaea officinalis is native to Europe, western Asia, and North Africa, growing on damp, brackish ground near the coast, along tidal rivers, and in marshes and ditches. It has naturalised in similar habitats in eastern North America.

Suggested Uses

Grown in herb gardens, damp and coastal borders, bog-garden margins, and wildlife plantings, spaced about 18-24 inches (45-60 cm) apart. The mucilage-rich roots are used in confectionery and herbal preparations, and the late flowers feed bees.

How to Identify

Marsh mallow is recognised by its tall, softly velvety grey-green stems and leaves and its pale pink mallow flowers 1-2 inches (2.5-5 cm) across in late summer. The whole plant feels soft and downy, and the broad leaves have shallow lobes and toothed margins. A central column of fused stamens sits at the heart of each flower. Its coastal, brackish habitat and dense velvety hairs separate it from the rougher common mallow (Malva sylvestris).

Appearance

Size & Dimensions

Height3'3" - 6'7"

Width/Spread2' - 3'

Reaches mature size in approximately 2 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~10 weeks

Summer

Flowering runs from July to September, with pale pink flowers opening a few at a time in the upper leaf axils. The blooms draw bees and other long-tongued insects to their nectar and pollen. Flat ring-shaped fruits follow, splitting into many single-seeded segments as they dry.

Detailed Descriptions

Foliage Description

grey-green, velvety

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 8.0(Neutral)

357912

Soil Types

loam clay

Drainagemoist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Althaea officinalis grows in full sun to part shade on deep, moist, fertile soil and tolerates brackish and seasonally wet ground that many perennials cannot. It is hardy in roughly USDA zones 3 to 9 and dies back to the crown each winter. Steady moisture suits it, and it copes with heavy and saline soils, though it flowers most freely in an open, sunny position. It is raised from seed, division, or root cuttings, and self-sows where conditions suit. The roots and leaves are rich in soothing mucilage and are gathered for herbal use. Rust and mallow sawfly are the main pests.

Pruning

Faded stems are cut back to the ground in late autumn or winter once growth dies down. Removing spent flower stalks before seed forms limits self-seeding. Clumps can be lifted and divided in spring to keep them strong.