How to Grow and Care for Marsh Mallow Plant

The marshmallow sweet treat we all know and love is based on a confection made by the ancient Egyptians from the root of Althaea officinalis (Marsh Mallow). Today's marshmallow treats, however, no longer contain any trace of the plant; the marsh mallow is now only grown as an ornamental plant.

Marsh mallow plants grow three to six feet tall and can put on quite a dramatic show in the garden while in bloom. Their tall elegant spikes are covered with almost white to blush or light pink 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. Depending on your climate, they can be planted from seed in the fall or spring.

Common Name	Marsh mallow
Scientific Name	Althaea officinalis
Family	Malvaceae
Plant Type	Perennial, herb
Mature Size	3-6 ft. tall, 2.5 ft. wide
Sun Exposure	Full sun
Soil Type	Moist
Soil pH	Acidic, neutral, alkaline
Bloom Time	Summer
Flower Color	White, blush, light pink
Hardiness Zones	3-9 (USDA)
Native Areas	Europe, Asia

Marsh Mallow Plant Care

The plant is generally easy to care for and an excellent option for wet gardens.

Because marsh mallows like full sun, be careful not to plant them somewhere in which taller plants will crowd them out. And, while they need moisture (that's where the marsh part of the name comes from), it's important that the soil in which they are planted has good drainage.

You can either plant marsh mallow seeds directly in the ground in the late fall if your area has mild winters, or in the early spring if your winters tend to be frosty. In either case, you'll want to plant the seeds about 18 to 24 inches inches apart and mulch the plants heavily to keep weeds at bay. Keep the area free of weeds until the plants are tall and established and then they'll be able to fend for themselves.

Light

Marsh mallow plants need full sun, they do not do well in the shade.

Soil

True to its name, the marsh mallow plant likes marshy, wet areas. If your property has an area with consistently damp soil and full sun, this plant will be happy.

Marshes also have slightly acidic conditions. To create a slightly acidic, moisture-retaining sandy loam environment, you can add sand and compost to the soil, including used coffee grounds. But don't worry too much about achieving acidic soil conditions, though, as these plants are not fussy about soil pH levels.

Water

Moisture is essential for marsh mallow plants. If you're trying to grow them in an area that tends to stay dry, they very likely won't flourish. However, standing water areas might be too wet for them.

The plants do need a fairly consistent state of moisture. Using moisture-retaining soil amendments such as organic matter can be advantageous. If your plants return the year after planting, you'll know the moisture levels are hospitable.

Temperature and Humidity

Marsh mallows tend to be tough plants and can thrive in a variety of different climates and humidity levels. They are extremely cold tolerant although, during sub-freezing temperatures, they will die back. They will, however, emerge again in the spring.

Fertilizer

Marsh mallow plants grow in such a wide range of soils (they can even tolerate salty soil), that applying a special kind of fertilizer isn't really necessary, especially if you have already added organic matter to the soil.

Pruning

It's not strictly necessary to prune marsh mallow plants, but it is a good idea to deadhead spent flowers and remove any dead leaves to prevent them from attracting unwanted pests.

Propagating Marsh Mallow

Marsh mallows are easy to propagate by root division:

1. Wait for the plant to go dormant in the late fall or early winter before the ground freezes.
2. Dig up the plant with its entire root system.
3. Divide the root mass using a sharp spade.
4. Replant the sections in a new suitable location.

Propagation by division can also be carried out in the early spring before foliage has begun to sprout although, because the plants die back in the winter, it could be difficult to find them before they start growing.

How to Grow Marsh Mallow Plants From Seeds

Marsh mallow plants can be easily planted from seed. It's not very common to see them for sale in a garden center, but you can order the seeds online. The seeds need cold stratification 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 bag with some lightly-moistened peat moss. This will mimic the winter dormancy period required by the seeds to germinate.

After the cold stratification period, start the seeds indoors three to four weeks before the last frost date, or sow them outdoors once the danger of frost has passed.

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

Potting and Repotting

Growing marsh mallows in containers is not recommended as the plant needs consistently wet soil, which is difficult to maintain because container plants dry out much faster than garden soil.

Overwintering

As marsh mallow is extremely cold tolerant and dies back in the winter months, there is no need to take any special precautions for overwintering. It is, however, always a good idea to cut away any dead stems or leaves to keep your garden tidy and increase airflow around the plants when they re-emerge in the spring.

Common Pests and Plant Diseases

Even though nearly all parts of the marsh mallow plant are edible, it is mostly left alone by pests. One invader that might decide to feast on your marsh mallows, however, are flea beetles. Flea beetles are small brown, black, or grey insects that could lay their eggs near the plant's roots, which provide nourishment for the larva. The larva then can feed on the leaves, leaving pinprick-sized holes. If the problem arises, apply neem oil, which is organic.

In terms of diseases, marsh mallows are quite disease-resistant, except for rust, a fungal condition that sometimes plagues the plant. It presents itself as raised white dots on the underside of leaves which eventually turn orange, then yellowish-green, and finally black. If you see this condition, remove any affected leaves, avoid overhead watering and apply a copper-based fungicide.

Common Problems With Marsh Mallow

The only problem you might have with this hearty plant is a lack of water, which will cause them to die. So you'll either want to plant them in an area that is naturally moist or keep them on a steady watering schedule to prevent the soil from drying out.

How to Get Marsh Mallow to Bloom

If your marsh mallow plant fails to bloom, the reason is most likely lack of sun. Move it to a location where it receives full sun, six to eight hours per day. You could also prune surrounding plants that cast shade on it to let in more sunlight.