How to Grow Marshmallow Plants

Close up of pale pink flower with dark pink center, five petals
The marshmallow flower has fuzzy leaves and stems, and a pleasing pale pink flower with dark pink stamens.

 Jeremy Halls / Flickr / CC BY-SA 2.0

In This Article

The marshmallow plant, also known as marsh-mallow, is a useful perennial with many medicinal uses. Althaea officinalis has a rich history that has been described in historical documents from Egyptian, Roman and Syrian sources, and its use as a food source made it an important plant in civilizations going back centuries.

The marshmallow candy we all know and love is based on a confection made by the ancient Egyptians from the plant's root. When this is boiled it creates the gelatinous substance and texture marshmallows are famous for. Today's marshmallows, however, no longer contain any trace of the plant. In times of famine following crop failure in Syria, marshmallow root was a crucial source of food. In addition to the medicinal and nutritious properties of the marshmallow's roots, the flowers are also edible and can be eaten in salads.

The plant is sometimes confused with the common mallow (Malva sylvestris) but its appearance can be differentiated by its multiple stems, the fuzzy down on its stems and foliage, and the blush colored flowers. These are smaller, paler and more numerous than the common mallow, with a darker pink center.

It is also easily confused with Lavatera or tree mallow. The common mallow has a darker-colored flower that looks purple; while the marshmallow can sometimes range from an almost white color to a light pink; lavatera's flowers are a bright shade of cotton candy pink and the leaves are spiky.

Marshmallow plants grow between four to five feet tall and can put on a quite a dramatic show in the garden while in bloom. Their tall elegant spikes are covered with flowers from July to September. They're also loved by pollinators. Brown seed pods begin to form in Late September, releasing tiny black seeds when mature.

Scientific Name Althaea officinalis
Common Name Marshmallow, marsh mallow
Plant Type Perennial herb
Mature Size 4 to 5 feet
Sun Exposure Full sun
Soil Type Moist soil, marsh
Soil pH Slightly acidic
Bloom Time Summer
Flower Color Pale blush to pink
Hardiness Zones USDA 3 to 7
Native Areas Europe, Western Asia, North Africa
Toxicity Not toxic
Group of tall plants with pale pink flowers on spiky stems in a meadow.
Marshmallow plants grow wild along marshy banks or near lake beds. They're beloved by pollinators and reseed freely.  Jane Webber / Flickr / CC BY 2.0

Marshmallow Plant Care

Marshmallow plants reseed themselves, though are not terribly invasive. You may see them growing along a marshy roadside or in a meadow, and sometimes a volunteer will pop up in a home garden. They are generally easy to care for, and can be a good option for wet gardens.

Soil

True to its name, the marshmallow likes marshy, wet areas. If there's a spot in your yard where the soil stays damp this may be a good place to grow these plants.

Marshes also have slightly acidic conditions, so adding some peat moss to your planting area may help the marshmallow feel more at home. Other soil additives to add include some sand and compost, including used coffee grounds. You are aiming for a slightly acidic, moisture-retaining sandy loam mixture. Don't worry too much about getting acidic conditions, though, as these flowers are not fussy about pH levels.

Light

Marshmallow plants like full sun, but if you only have limited sun available (at least four hours), then morning sun is preferable so the flowers will open up.

Water

Moist soil is best for marshmallow plants, and if you're trying to grow them in an area that tends to stay dry they very likely won't flourish. Standing water areas may be too wet for them, however.

The plants do need a fairly consistent state of moisture. Using moisture-retaining soil amendments may help. Peat moss and compost added to your soil can be advantageous. If your plants return the year after planting, you'll know the moisture levels are hospitable for your marshmallows.

How to Grow Marshmallow Plants From Seeds

Marshmallow plants can be easily planted from seed. It's not very common to see a them for sale in a garden shop, but you can order the seeds online. The seeds do best if they go through a cold stratification process before planting, mimicking their cycle in nature.

You can place your seeds in the refrigerator for a few weeks, whether in their package or in a plastic baggie with some lightly-moistened peat moss. This will mimic the winter dormancy period needed for the seeds to germinate.

Start the seeds indoors three to four weeks before the last frost date, or sow outdoors once the danger of frost has passed.

Sow them in groups of five or six seeds, in groupings 18-24 inches apart. Lightly cover them with soil, and keep moist until they germinate. This usually takes about three to four weeks. Once established, these hardy plants will return every year.