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How To Grow Marsh Mallow (Althaea Officinalis)

I have a problem area in my garden that doesn’t get much sunlight and has water logged soil. I haven’t been able to solve these problems but I am hoping to grow some pretty fabulous native plants there to try and make the most of a soggy situation.

Marsh Mallow from the Malvaceae family is the perfect solution to a wet or boggy area in your garden. A hardy perennial that requires full sun to partial shade, but that is also frost tolerant. It will grow to heights of 1.5 meters and a spread of about the same.

Marshmallow is attractive to bees and pollinators in your garden. This native herb has a lot to offer the British gardener, but also USDA zones 3-9, I will convince you I promise!

marsh mallow plant

What Is The Marsh Mallow Plant

Marsh mallows are native to Northern Europe and Africa. This means they thrive in a variety of climates and with various soil types.

A herbaceous perennial Marsh Mallow loves slightly boggy soil, it is not fussed about Ph or nutritional values, just free draining for preference. Growing in partial shade to a height of around 1.5 meters with a spread of the same. Fully frost tolerant and will survive temperatures of below -15 C.

Marsh Mallow produce those architectural stalks of flouncy childlike flowers, making them a bit of a favorite in our garden!

Other names for marsh mallow include; marshmallow, bismalva, guimauve, Joseph’s staff, mauve, mortification root, white mallow, wymot, wymote, buttonweed, cheese plant

The really exciting part about this plant is that it was the original marshmallow sweet. The National Confectioners Association has a great read about the history of the use of sap from the root of marsh mallow. As early as 2000BC Egyptians were using it to make candy!

Malva Neglecta is common Mallow and well known as an invasive weed in America. Being from the same family as Marsh mallow they are very much tarred with the same brush in people’s eyes.

Growing Marsh Mallow From Seed Indoors

  • Sow marshmallow seeds indoors in late Autumn/Fall
  • Prepare tray of compost and water them well.
  • Lay marsh mallow seeds out evenly to avoid clumping and cover with perlite.
  • Cover over and check back every few weeks.
  • Germination is not guaranteed with this process but you should see seedlings emerging in Spring.
  • Plant out younger seedlings in a moist plant bed with full sun to partial shade. The marshmallow will grow up to around 1-1.5 meters in height so be sure to companion plant with other tall plants or those who are not too keen on direct sunlight.

Sow Marsh Mallow Seeds Direct

To general you have a longer sowing period with sowing directly and your germination rate is not affected. Marsh mallow will benefit from moist but well draining soil. Sow seeds in rows 50cm apart. March – July tend to be good sowing periods if you have passed the fear of frost.

In the UK this is unlikely until April. The later you sow the lower the chance of flowers in the first year. Work it into the back of a border or a flower bed that you want to make into a wildflower meadow.

Once the seedlings are large enough to handle thin them out to their final location of around 50cm apart. You can interplant well with other taller herbs like Angelica and Mullein.

Marsh Mallow will grow to flowers reaching 1.5 meters in height. The spread is likely in excess of 60cm. We grow not just for the flowers which come from about July to late September but also for the furry grey green foliage. The flowers are the colors of soft pink and white marshmallows.

Using Division To Propagate Marsh Mallow

This is by far the simplest method of getting new plants. But of course, you need plants sown to get to this stage!

Once you have cut back your marsh mallow you can use division to propagate. This can be late Fall / Autumn or early Spring. Simply loosen the soil around the plant with a fork and then use a sharp spade to slice your marsh mallow in half. Lift out with the fork and relocate. Backfill the space with compost.

When you lift the marsh plant out with your fork you will see a natural place to slice it and then you can go from there.

TOP TIP – Spring is a dormant time, but it can be hard to find your marsh mallow plants. So perhaps harvest and cut back, then use division at the same time. Marsh mallow will really appreciate division as it gets over crowded very quickly.

How To Care For Your Marsh Mallow Althaea Officinalis

I would suggest that native plants are ideal for beginners as there is little that can go wrong.

Marsh mallow will be a hardy perennial that requires cutting back after the flower stems have gone over in Autumn / Fall. This looks like a physical slump from the flowering stem. Cut all foliage back to between 2-3cm from the base. Mulch well with organic matter and wait for a Spring return.

Marsh mallow can be prone to flea beetles or the disease ‘rust’.

Flea Beetles

There are many sub species of flea beetle included under this umbrella name. The signs of an infestation include a peppering of holes on the leaves of brassicas. Not such an issue for your mature marsh mallow as it will survive a few leaves being eaten and you can discard the effected leaves without too much of an issue. However young seedlings can completely be consumed by an infestation.

The good news is that your marsh mallow will also provide habitat for beneficial bugs in your garden. Bugs that will seek and destroy flea beetles. So it is possible to survive a flea beetle attack and enjoy watching your ground beetles eating the larvae of the pesky pests.


Rust is a fungal disease which can reduce your plants vigor, or in some cases completely kill it off. Displaying as pale leaf spots or pustules that are orange, yellow, red or rust colored. Treatment can be picking leaves and disposing of them or it can require more vigorous treatment and clearing all of the surrounding area of potential carrier spores.

WORD OF WARNING – Rust fungus has spores that are extremely frost resilient so do not think a cold winter will finish them off. Equally you will spread the problem if you clear the area of organic matter and then add it to your compost bin. Incinerate the waste material, or leave in your councils garden waste bin.

A further tip to reduce the chance of developing rust is to avoid nitrogen rich feeds and fertilizers on your plants. Only in affected areas, but this may help a little.

Planting Guide For Marshmallow

This is where applying a bit of problem solving comes in handy.

We chose marsh mallow to fill a slightly boggy spot and truly this is where it can be found in the wild. Other plants that love marsh lands and wetlands will be great companion plants. Just bear in mind the ultimate spread of your marshmallow and how this will affect the amount on hours of sun other plants will receive.

Growing marshmallow near to a pond that you want to encourage native wildlife to will really make sense. The foliage provides great cover for frogs or toads and will be a cool spot for those species who need a break from the midday sun.

Harvesting Mash Mallow

You can harvest a limited amount of leaves and flowers as your marsh mallow grows. Don’t be tempted to over harvest as marsh mallow will need plenty of sunlight to grow.

Leaves can be used in salads and wild pesto. Flowers are edible and make a lovely addition to cocktails and salads alike.

Harvesting Marsh Mallow Root

If you want you can save the plant and harvest the roots for medicinal or culinary use.

The trick to saving the marsh mallow when harvesting the root is to wait until the 2nd or 3rd year. Once you have cut back completely in Fall / Autumn you can lift with a fork and then use a sharp spade to remove the roots. Replant the crown and offer some protection from the severe frosts.

Use a hose to rinse the majority of the soil off and then bring inside to clean more thoroughly. You do not need to peel or cook your marsh mallow root. Instead slice into 1/2 inch rounds and dry in a dehydrator. For a full guide on drying times have a look at our article here.

Marsh Mallow Grows Guide

Further Reading

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