Marsh mallow Althaea officinalis
Marsh mallow (Althaea officinalis) is an evergreen perennial herb in the Malvaceae family, native to Europe, western Asia and North Africa (brackish marsh edges). It grows 1–1.5 m (3.3–4.9 ft) tall and 50–80 cm (20–31 in) wide, wants full sun and high water, and is hardy to about -30 °C (-22 °F). Space plants about 60 cm (24 in) apart.
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Marsh mallow at a glance
| Type | Perennial herb, evergreen |
|---|---|
| Family | Malvaceae |
| Mature height | 1–1.5 m (3.3–4.9 ft) |
| Mature spread | 50–80 cm (20–31 in) |
| Spacing | 60 cm (24 in) centre to centre |
| Sun | Full sun, at least 5 h of direct sun a day |
| Water | High; drought tolerance low, waterlogging tolerance moderate |
| Soil pH | 6–8 |
| Cold hardiness | About -30 °C (-22 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 32 °C (90 °F) |
| Flowering | from about July for 6–9 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Yes: root (mucilage), young leaves, flowers |
| Native to | Europe, western Asia and North Africa (brackish marsh edges) |
| Common in gardens of | 🇬🇧 United Kingdom, 🇫🇷 France, 🇩🇪 Germany, 🇳🇱 Netherlands, 🇵🇱 Poland, 🇹🇷 Turkey, 🇺🇸 United States |
Is Marsh mallow toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Not poisonous. Its mucilage can slow the absorption of medicines taken at the same time.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Marsh mallow
No well-documented helpful pairing. Group it with plants that like full sun and high water.
Questions about Marsh mallow
- How far apart should I plant Marsh mallow?
- About 60 cm (24 in) apart, centre to centre. A mature plant spreads 50–80 cm (20–31 in).
- Does Marsh mallow need full sun?
- Full sun: at least 5 hours of direct sun a day.
- How much water does Marsh mallow need?
- High water. Drought tolerance is low and waterlogging tolerance moderate.
- How cold-hardy is Marsh mallow?
- It tolerates about -30 °C (-22 °F) once established, roughly USDA zone 4.
- When does Marsh mallow flower?
- From about July for 6–9 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Marsh mallow poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Not poisonous. Its mucilage can slow the absorption of medicines taken at the same time.
- What grows well with Marsh mallow?
- There is no well-documented companion pairing for Marsh mallow. Group it with plants that like the same sun (full sun) and water (high).
Sources and evidence
Evidence grade A (A: strong evidence).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- Herbal monographs (European Union herbal monographs and assessment reports), European Medicines Agency, Committee on Herbal Medicinal Products
- RHS Find a Plant (plant profiles and growing guides), Royal Horticultural Society
Notes and assumptions
- Velvety grey leaves and pale pink mallow flowers. The mucilage of its root thickened the original marshmallow sweets (French pâte de guimauve) before gelatine replaced it. Likes moist, even slightly salty soil.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
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