Stems 3 to 5 feet tall, flowers cute enough to scatter over a salad, and roots so rich in mucilage they turn up in cough syrup: marshmallow (Althaea officinalis) earns its place as herb and ornamental alike. Give it full sun and moist, rich soil — even salty ground will do.
| Name | Althaea officinalis |
|---|---|
| Family | Malvaceae (mallow family) |
| Type | Herbs and spices, perennial |
| Height | 3 to 5 feet (1 to 1.5 m) |
| Exposure | Full sun |
| Soil | Rich enough |
| Flowering | Early summer to early autumn |
| Harvest | Midsummer to early autumn |
Marshmallow requires sun, ideally soft sunlight and moist, rich soil. It can grow in salty soil, too.
Proceed to sow directly in the plot starting in May-June or at the latest during the month of July.
Growing marshmallow in pots is never really successful, we strongly advise that you spend your efforts for something less ungrateful…
Space plants about 2 feet apart, since each clump throws up several stems and ends up 3 to 5 feet tall.
Barely cover the seed and keep the seedbed damp until the shoots appear.
Marsh mallow (Althaea officinalis) naturally grows in damp ground and does best in consistently moist soil, so water deeply during prolonged dry spells and mulch around the crowns to conserve moisture.
Cut the dead stems down to ground level once they wither, because fresh shoots rise from the rootstock rather than from old growth.
All parts of the plant (roots, leaves and flowers) can be collected to be eaten.
Wait for the summer to gather them.
Watch out for small bugs!
Although marshmallow is left alone by most critters, it is however highly vulnerable to rust. Also, avoid planting your marshmallow near hollyhock because rust attacks would do double the damage.
Marsh mallow (Althaea officinalis) grows wild in damp, brackish ground and salt marshes, so keep its soil consistently moist, especially while plants are young, though established clumps tolerate occasional drying.
Water at the base of the clump rather than over the foliage, since leaves that stay wet invite rust.
Pick off leaves showing orange rust pustules as soon as you spot them, and bin them rather than adding them to the compost heap.
Digging the root kills that plant, so lift only part of a clump and leave the remainder to bulk up.
Marshmallow itself is grown as the single medicinal species, but its relatives in the mallow family give the same tall, open-faced flowers in far more colours. Keep hollyhocks at a distance from the marshmallow patch, since rust spreads readily between them.
| Variety | Height | Flower colour | Why grow it |
|---|---|---|---|
| ‘Alba’ | 2 to 3 ft | Pure white | Long season, thrives on poor soil |
| Spring Celebrities Series | 2 to 3 ft | White, pink, lemon, carmine | Short enough for pots and front borders |
| ‘Chater’s Double’ Group | 6 to 8 ft | Mixed, fully double | Cottage-garden spires, peony-like blooms |
| Halo Series | 5 to 6 ft | Single, dark contrasting eye | Open single flowers, very good for bees |
| ‘Nigra’ | 6 to 8 ft | Near-black maroon, single | Dramatic colour against pale walls |
| ‘Zebrina’ | 3 to 4 ft | Pale pink with deep purple veins | Flowers within months from a spring sowing |
| ‘Barnsley’ | 6 ft shrub | White with a red eye, ageing pink | Shrubby structure, flowers all summer |
The only known species is the one harvested for medicinal purposes. However, a cousin species deserves to be mentioned: hollyhock (Alcea rosea) is also from the mallow family and is grown as an ornamental plant.
Hollyhock has the same medicinal uses as marshmallow. However, its root doesn’t contain as much mucilage. Refreshing drinks can be colored with the purple flowers of hollyhock and its leaves can be eaten like other cooked greens.
Check that the label reads Althaea officinalis, since products sold simply as “mallow” may instead be Malva sylvestris, a different species whose root is not the traditional mucilage-rich marshmallow drug.
Velvety, grey-green felted leaves are typical of true marshmallow (Althaea officinalis), but other hairy mallows share that trait, so confirm identification with flowers, seed pods, and the plant’s thick, mucilaginous root.
Hollyhocks are short-lived and generally need resowing, while marshmallow is a genuine perennial that regrows from its rootstock.
Both a very beautiful ornamental plant and herb used for medicine and cooking, marshmallow is one of the ingredients in the traditional sweets that bear its name.
This is a very melliferous plant.
With high levels of mucilage, it boasts relaxing and moisturizing properties and thus is included in certain medicines like cough syrup.
Steep marshmallow root in cold water for several hours, the traditional method for drawing out its soothing mucilage, though claims that heat destroys that mucilage are not well established.
Standard guidance is to lift marshmallow roots from well-established plants at least two years old rather than young seedlings, whose roots are thinner and yield much less usable material per plant.
Scrape the corky skin off the lifted roots and slice them before drying, because whole roots stay damp at the core and turn mouldy.
Mucilage from marshmallow can slow the absorption of other medicines, so space the two well apart.
The flowers are edible and can be added to your mixed salads and desserts!
