Althaea officinalis
herbMarshmallow (Althaea officinalis) is the original marshmallow - a tall, elegant perennial of damp meadows and ditches, 3 to 5 ft high, with soft, velvety gray-green leaves and pale pink, hibiscus-like flowers. Every part is rich in mucilage, the slippery substance for which it has long been grown; the confection was once made from its root. Native to salt marshes and riverbanks, it loves moist ground and full sun, draws bees, and is grown for its root (dug in autumn), leaves, and flowers. It is hardy, long-lived, and easy once established in soil that does not dry out.
Sun
full sun
Water
Every 5 days
Harvest
~120 days
Difficulty
easy
Lifecycle
perennial
Comes back every year
Spacing
18-24 in. apart
Planting Depth
Barely cover seed; cold-stratify
Soil pH
6.0-8.0
Soil Type
Rich, moist, sandy
Hardiness Zones
Zones 3 – 9
When to Fertilize
Spring; compost
Fertilizer
Compost; moderate needs
Grow marshmallow in rich, moist, sandy soil in full sun, mimicking its native damp meadows - it tolerates wet ground and even salt that defeats other herbs. Sow seed in fall (it benefits from cold stratification) or start indoors 8 weeks before the last frost, and transplant 18 to 24 in. apart. Keep the soil consistently moist, especially the first year and in dry spells, as drought checks growth and toughens the root. Add compost to retain moisture. The roots are not dug until the plant is at least two years old, so plant it where it can stay put; cut back spent stems in fall.
Start seeds indoors
Feb 18
Transplant outdoors
Apr 29
Projected first harvest
Aug 27
Good neighbors that attract beneficial insects or deter pests
Proactive ways to stop trouble before it starts — tap a name with an arrow for its full guide
Mallow-family rust spots the leaves - give airflow, avoid wetting the foliage, and remove affected leaves
Hand-pick in the cool morning into soapy water; they favor the soft leaves and flowers
Rinse colonies from shoot tips; predators usually follow
Harvest the leaves and flowers through summer for fresh use or drying. Dig the roots in autumn of the second year or later, after the tops die back, lifting the whole clump, cutting off a portion of the thick root, and replanting the rest to regrow. Wash and slice the roots and dry them well. All parts are dried for teas and infusions, prized for their slippery mucilage.
Every part of marshmallow is edible and rich in mucilage: the leaves and flowers go into salads and teas, the young shoots can be cooked, and the root - the source of the original marshmallow sweet - is simmered into infusions. It is grown as a traditional herb and a handsome, bee-friendly perennial for damp ground.
For educational and informational purposes only — HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.