Marshmallow Herb Growing Guide

How to Grow Marshmallow Herb from Seed

  • Scientific Name: Althaea officinalis
  • Hardiness Zone: Annual, Perennial Zones 3-9
  • Days to Harvest: 80-90 days (from date of transplanting)
  • Days to Maturity: 90 days
  • Days to Germination: 14-21 days
  • Seeding Depth: ¼”
  • Plant Width: 24-30"
  • Plant Height: 36-60"
  • Growth Habit: Bushy and upright wildflower
  • Soil Preference: Fertile, consistently moist, well-drained
  • Temp Preference: Temperate, 60-75°F
  • Light Preference: Full sun - partial shade
  • Pests/Diseases: Marshmallow has a weed-like hardiness with a tolerance to disease but can be susceptible to aphids, spider mites, flea beetles
  • Availability: See All Marshmallow Varieties
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Growing Marshmallow

Marshmallow (Althaea officinalis) is a cold-hardy perennial that requires little maintenance. It is native to western Europe and North Africa and is particularly notable in ancient Egyptian history. Marshmallow was used for medicinal and edible purposes then and still is used for those purposes today. Egyptians used marshmallow herb to create a confection using the sap in the root that inspired the marshmallow treat we know today. They used this confection to treat sore throats and it was reserved for royalty and the gods. Today, there is no marshmallow herb present in the modern marshmallow, as gelatin replaces the root sap. Marshmallow is known for its medicinal purposes, specifically for respiratory issues. It is known to treat dry coughs, pain and swelling of the mucous membranes that line the respiratory tract, and irritation of the throat and mouth. The sap works by forming a coating over the skin and digestive tract. Marshmallow flowers, root, and leaves of the plant are all edible while the medicinal properties come from the sap inside of the plant.

How to Grow Marshmallow from Seed

  • Sow seeds just below the surface, about ¼” at most
  • Requires moist, loamy soil conditions to thrive
  • Cold stratify for thorough germination

When planting marshmallow, sow seeds just below the surface of the soil, at most 1/4" into the soil. Marshmallow is commonly planted in the late fall as marshmallow seeds require cold stratification for germination. If planted in warmer conditions, marshmallow does not tend to thrive as well and may require a 4-to-6-week period of refrigeration mixed with peat moss before it is planted to ensure that it is able to germinate correctly. This method works for pot-planting as well. It is best to sow 5-6 seeds per plant, spaced 12-24 inches from one another.

Marshmallow requires moist, loamy soil and enjoys marshy conditions, true to its name. Make sure that the soil stays moist at all times for optimal growth. If the soil is not retaining moisture as it needs, consider mulching the soil to aide this process. If grown in a pot, it may need watered more frequently as pots are known to dry soil out. When growing marshmallow, it is important to keep an eye on the soil’s moisture levels as marshmallow does not thrive in dry conditions.

Marshmallow Soil

Marshmallow, true to its name, prefers marshy areas and moist soil. It also grows best in conditions that are slightly sandy, as the sand will retain some of the moisture needed for the plant to thrive. It grows best in wet conditions; however, it enjoys well-drained soil and likely will not thrive in areas of standing water or underwater. It does not do well in dry environments but will usually tolerate slightly drier conditions. Marshmallow pants are hardy and because of this, usually do not require fertilization. Fertilization rarely is needed for these plants, but in the rare case it is, fertilize the soil before planting the herb, or do it every few years. The plant prefers a slightly acidic environment, within the pH range of 6-7, but will grow in most pH levels. It is not too picky about conditions, as long as receives consistent watering to its soil. As a good rule of thumb, ensure that it receives at least 1-2” of water a week.

Watering Marshmallow

  • Keep soil consistently moist and watered
  • Keep well-drained and free of standing water
  • Thrives in marshy, cool conditions

Marshmallow prefers consistent and regular watering. If it is in a marshier area, it should retain enough moisture from the soil as to not need watered too often. In drier conditions, it may need kept an eye on to ensure that it is receiving adequate moisture for optimal growth. The plant does well in warmer and cooler environments, as it prefers full sun but enjoys partial shade as well. Marshmallow thrives in marshy, moist conditions. It enjoys regular, heavy watering and is tolerant of most conditions as it is a hardy plant. However, it will likely not thrive in super dry conditions. It grows best in cooler climates, which is why it is usually planted in the late fall so that it can germinate throughout the winter. While marshmallow prefers wet marshy conditions, do not plant it in areas of standing water or underwater as these areas provide too much moisture for the plant and can cause it to fail.

Is Marshmallow A Perennial?

Marshmallow is a perennial that is hardy in zones 3-9. It may be planted in different seasons according to the hardiness zone in which it is planted; however, marshmallow most often planted in the fall or early spring. Marshmallow may be started at any time indoors, as long as it receives cold stratification during germination. This may be achieved by placing the seeds in the fridge 4-6 weeks in total before transferring them to a pot filled with soil. Marshmallow fully blooms its flowers in late summer months, between August and September. In the fall, the plant dies and then returns that following spring without needing to be replanted. Marshmallow will readily self-sow and does not require much maintenance. Marshmallow is considered invasive in some areas as it reseeds itself. To make sure that marshmallow does not spread more seeds than desired, pluck its flowers before they fully blossom.

Marshamllow in Winter

  • Requires cold stratification during germination
  • Winter hardy down to zone 3
  • Still needs plenty of sunlight

Marshmallow withstands the cold well, and even prefers cooler temperatures. When marshmallow goes through the process of germination, it requires cold stratification to mimic winter weather conditions. Some people do this outside during the winter or place seeds in the fridge for 4-6 weeks before planting them. Marshmallow can survive down to USDA zone 3. If grown inside during winter, it's important to make sure that the plant receives enough sunlight and that the conditions of the building are not too humid.

Growing Marshmallow in Pots

Marshmallow does well in pots. The only issue with potting marshmallow is that the soil may dry out far quicker than if it were planted outside, which is something to be cautious of as Marshmallow prefers wet soil. To make sure that marshmallow receives enough moisture, it may have mulch added to it for retention. When in a pot, keep marshmallow in a space that receives an ample amount of sunlight. A grow light may be a helpful addition to ensure that it receives enough light. Marshmallow can grow up to 4-5 feet tall, so it is important to make sure that it has enough space in its pot for growth. It may need moved after time if it becomes too tall. This is why many begin marshmallow indoors but eventually move it outdoors.

How to Care for Marshmallow Plants in Pots

  • Germinate first and then transplant
  • Choose correct pot size and move up as needed
  • Make sure that it receives enough water and sunlight

Caring for marshmallow in pots is relatively easy, as the herb does not require much care and tends to itself. As long as it receives full sun and is regularly watered, it tends to fare well whether planted indoors or outdoors. When planting it in a pot, make sure that the seeds have been able to germinate properly. Most often, marshmallow seeds are germinated in a fridge for 4-6 before being planted in a pot. This ensures that they grow properly. Make sure that its pot is big enough, as it will require to be moved to larger pots as it grows. Additionally, make sure that the pots have draining holes in them to ensure that there is no standing water within the soil as this can cause the plant to wilt. Marshmallow prefers wet conditions and marshy soil, but also enjoys soil that is well-drained and does not retain too much moisture.

Growing Marshmallow Indoors

Marshmallow is most commonly grown outdoors but may also be grown indoors. It fares well inside as it does outside, as long as the conditions for growth are right. Marshmallow really only requires sun, water, and cooler conditions to thrive. The hardy herb is tolerant of warmer temperatures as it is known for blooming in the late summer months. It can survive in warmer conditions, even those inside, but it is important to make sure that the room temperature is not too humid, or the plant will ultimately fail. Marshmallow requires wet conditions to keep the soil moist and cool. Pots may cause dry soil quicker than in-ground planting, so it is important to regularly check the soil's moisture level. If it has a hard time retaining moisture inside, consider adding mulch to the soil or transporting it into another pot with soil that has been lightly fertilized with organic matter.

Marshmallow Companion Planting

Marshmallow is a companion plant for its ability to attract certain bugs, which can deter them away from other plants. More specifically, marshmallow attracts harlequin bugs which are very harmful to cabbages and other related crops. By focusing on the layout of a garden, you may plant marshmallow on one side and keep such plants on the other side of the garden as to distract these pests from destroying them. In this situation, the marshmallow plant is able to camouflage and protect other plants. This relationship is vital, as harlequin bugs are not known pests of marshmallow. Marshmallow also attracts pollinators with its flowers, particularly bees. An example of an ideal planting companionship would be between marigolds and marshmallow. Marigolds are known for their ability to keep aphids away, which is the biggest pest threat for the marshmallow plant. In addition to this, marshmallow and marigolds are both known for attracting pollinators. By planting both of them together, or rather another plant that shares a similar relationship in its mutual benefits to marshmallow, both plants are able to thrive more easily by being placed against each other in a gardening environment.

Marshmallow Flowers

Marshmallow flowers are pale pink in color with dark pink to purple stamens. They have leaves and stems that have been described as fuzzy and have a smell similar to honey. Some people believe the flower and leaves to smell bland, however. The flowers carry mucilage in them just like the rest of the plant—having a gooey sort of taste. This mucilage is good for coating the respiratory tract and protecting the throat from dry coughs and irritation. The flower is completely edible just like the rest of the plant. They do not grow very big, only to about 2 inches in diameter, but are appealing to the eye.

Harvesting Marshmallow

The entire marshmallow plant may be harvested, including its leaves, flowers, and roots. However, the root may be harvested only after a minimum of two years after its planting. This is because during the first year, its roots will not be established enough for harvesting. It is also best to give the plant a few years to become fully established as once it is, it requires little to none outside care beyond watering. The plant's leaves and flowers may be harvested at any time once they have grown. Marshmallow’s flowers are distinctive in look and taste, as they have pale pink petals and a dark pink to purple stamen. They also carry the same mucilage as the stems and roots do. This creates a gooey texture upon cooking and consumption of the plants. The plant is also characterized by its fuzzy stems and leaves, which may also be harvested.

When to Harvest Marshmallow

  • When plant has reached about 3-5 feet tall
  • Right before flowers have blossomed
  • Don’t harvest roots until at least 2nd year

How to Harvest Marshmallow

Marshmallow may be harvested differently, depending on which part of the plant is being harvested. The leaves may be harvested before and after flowering. The leaves may be cut with scissors or shears or be plucked by hand. If harvesting both the leaves and flowers, cut the stem with both attached. Since roots are the most commonly used part of the marshmallow plant, it's important to know how to properly harvest them. After 2-3 years of growing marshmallows, the roots will be readily available for harvesting. It is best to harvest them in the fall before the ground begins to freeze. You can pull the plant up by hand or with the help of tools as to not damage the stems and other parts of the flowers, since the roots grow long and thick. Only remove a portion of the roots, leaving enough to where there is an identifiable crown still connected to the plant. This will ensure that the plant returns the next year. Once you have harvested its roots, dry them immediately.

Drying Marshmallow

The different parts of the marshmallow plant may be approached differently in the case of drying. For the roots specifically, it is best to allow them to dry in an oven or dehydrator after grating or chopping them. When they are brittle to the touch, they may be taken out and cooled to room temperature. The leaves and flowers may be dried in oven dry or food dehydrator processes but may also be hang dried. To hang dry, hang the stem upside down and place in a paper bag, in a dry and dark room. They should be fully dry after a week or two. For oven and food dehydrator drying processes, keep them on a low temperature and place leaves and flowers in both machines separately. For an oven, it may take up to 20 minutes. Remember to keep the oven door open during this process so the leaves are not cooked. If they are not dry after 20 minutes, put them back in for 10-minute intervals until brittle. For drying in a food dehydrator, place leaves and flowers in separately on the lowest heat for up to 24 hours, checking on them in intervals. Once they are fully dry and look stiff, they are ready to be taken out.

How to Dry Marshmallow

Hang Dry: Place stems upside down in a paper bag with the leaves and flowers still attached. Tie a string to the bag and hang them in a dry, dark room for a week. After about a week, they should be fully dried. If not let them sit for another week.

Oven Dry: Heat up oven to 200°F. In the meantime, wash your roots and cut/grind them up (or place leaves and flowers in a single layer on a tray). When you are done prepping the marshmallow, place them on a tray and into the oven. Leave the oven at 200°F briefly then turn it off. Leave the door open so that they are not dried too quickly.

Food Dehydrator: To dry marshmallow in a food dehydrator, place one part of the marshmallow at a time on the drying rack. Its leaves, flowers, and roots may all be dried in it. Once the drying rack is inside the dehydrator, turn it on its lowest temperature setting and allow them to sit in there for up to 24 hours. You may check on them in intervals, but it should take up to at least 12-18 hours to fully dry depending on the part.

Types of Marshmallow

Marshmallow is a part of a large Malvaceae plants of the mallow family. Within this family there are hundreds of known species. Well known members of this family include lavatera, hibiscus, hollyhock, cotton, okra, and more. While all of these plants are within the mallow family, they are not marshmallow or a variety of it. They merely are within the same family. Marshmallow may be confused with the common mallow (Malva sylvestris) flower from name association, but these two are not the same. Marshmallow’s scientific name is Althaea officinalis. However, they are both classified as “mallows” and a part of the same family. A notable difference between the two different herbs is the color of their flowers. Marshmallow flowers are smaller than the common mallows’ and they are a pale color, resembling an opaque blush shade. The common mallow’s flowers are a bright mauve purple to blue. This is why the common mallow is also known as blue mallow, due to its deep blue-purple blossoms.

Benefits of Marshmallow

Marshmallow is considered to be highly medicinal, particularly its root, which is used in teas, tinctures, and other concoctions for herbal treatment of certain ailments. It is regarded as being anti-inflammatory, a diuretic, an emollient, able to treat an upset stomach, good for treatment of insect bites and wounds, among other qualities. It has also been used to naturally treat respiratory issues such as dry cough and to reduce pain and swelling of the mucous membranes that line the respiratory tract. Historically, marshmallow was used by many ancient civilizations. Perhaps most popular is the Egyptians’ use of it. They used the mucilage of the marshmallow root to create a confection, because when it is boiled it creates a gelatin-like substance and a soft texture, similar to the marshmallow treats we enjoy today. This Egyptian creation directly inspired the sweet treats we know as marshmallows today, although they do not use the plant anymore in production.

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