Polypodium vulgare: Care, properties, and complete growing guide

Complete guide to Polypodium vulgare: identification, care, properties, and uses

The Polypodium vulgare, Popularly known as common fern, sweet fern, polypodium o forest licorice, is a perennial plant of the Polypodiaceae family, widely distributed in temperate regions of Europe, Asia, and North America. Its presence in forests, walls, tree trunks, and rocky areas has made it a prized species both for its ornamental value and for its traditional uses in herbal medicine.

In this comprehensive guide, you'll discover all the details needed to identify, grow, and make the most of this fern, from its botanical characteristics to its care, medicinal properties, and applications in gardening and natural health.

Identification and botanical characteristics of Polypodium vulgare

• Scientific name: Polypodium vulgare L.
• Common names: polypodium, sweet fern, filipodium, forest licorice, xarranguilla, among others depending on the region.
• Family: Polypodiaceae.

the generic name Polypodium comes from the Greek "polypódion" (small octopus) due to the branched appearance of its rhizome, evoking tentacles or suction cups. The epithet vulgare refers to its common and widespread nature.

• Height and carriage: perennial plant, with a creeping (underground) rhizome that allows it to expand horizontally, forming dense colonies up to 40 cm high.
• Fronds (leaves): Deep green, narrow, deeply lobed, and fine-textured. They typically measure between 15 and 30 cm long, although there are varieties with wider or divided fronds.
• Emerging fronds: In spring, new leaves appear from the rhizome, renewing its appearance.
• Reproduction: does not produce flowers or seeds. It reproduces by spores, housed in groups called sori on the underside of the fronds, visible as small orange or yellow dots.
• Rhizome flavor: slightly sweet, similar to licorice, which has given it the name sweet fern.

Natural habitat and distribution

Polypodium vulgare is a cosmopolitan species, very resistant and highly adaptable, which explains its wide geographic distribution. It grows in:

• Wooded and mountainous areas: especially in humid undergrowth, where it benefits from partial shade and substrates rich in organic matter.
• Rock crevices, ancient walls and ledges: It is common to see it in cracks, on moss, on slopes and even at the base of trunks or on stone walls.
• Poor surfaces: It can colonize stony, acidic, slightly humid or, to a lesser extent, dry soils, but rarely thrives in very calcareous soils.
• Altitude ranges: from low altitudes to mountainous areas up to 3000 m above sea level.

Its natural habitat demonstrates its ecological versatility and value for environmental restoration, soil stabilization, and growth on epiphytic surfaces without damaging substrates or trees.

Varieties and related species

The gender Polypodium It includes between 75 and 100 species, both terrestrial and epiphytic, evergreen and deciduous. The following varieties of Polypodium vulgare are appreciated in gardening:

• Polypodium vulgare 'Bifido': more divided fronds, delicate and elegant appearance.
• Polypodium vulgare 'Cambricum': broad leaves and slightly rough texture.
• Golden Polypodium: known as “blue fern” or calaguala, with bluish fronds and rapid growth.

There are other related species used in traditional medicine (Polypodium decumanum, Polypodium cambricum, Polypodium argentinum), all with similarities in structure and reproductive cycle.

Medicinal properties and traditional applications

The rhizome of Polypodium vulgare It is notable for its sweet flavor, thanks to its saponin and active compound content, which gives it numerous properties valued in folk medicine and herbal medicine. It is credited with the following effects:

• Mild laxative: ideal for the treatment of occasional constipation.
• Cholagogue and hepatoprotective: it promotes the production and expulsion of bile, helping to decongest and activate liver function.
• Expectorant and antitussive: effective in relieving coughs, bronchial congestion and respiratory conditions such as bronchitis or asthma.
• Anti-inflammatory: rhizome poultices to relieve eczema, wounds, rashes and skin discomfort.
• Digestive: stimulates appetite, improves digestion and protects the gastric mucosa.
• Mild and purifying diuretic: facilitates the elimination of toxins.
• Anthelmintic: helps fight intestinal parasites.
• natural sweetener: The rhizome, thanks to its sweetness, has been used to sweeten infusions and medicinal preparations.

Folk tradition uses sweet fern to relieve liver problems, bronchitis, digestive problems, and as a general tonic. Its rhizomes can be consumed as an infusion, extract, or syrup, but it is essential to consult a healthcare professional before using it as a supplement or natural remedy.

Polypodium vulgare care: how to grow a healthy and vigorous fern

1. Light and location requirements

• Indirect light or partial shade: It thrives best in semi-shaded or shaded environments, such as those found in understory habitats. It tolerates soft early sunlight, but intense exposure can burn its fronds. Caring for the hart's tongue fern also shares these requirements in terms of light.
• Ideal for indoors, shaded patios, north-facing walls, or protected areas of the garden. If grown indoors, it's best to plant near windows with filtered light.

2. Temperature and climatic resistance

• Optimum temperature: It prefers cool environments, between 15 and 25°C, and can tolerate even slight drops below zero if it is dormant. For more information, consult Alexandrian laurel care.
• It tolerates light frosts, but it is advisable to protect it from prolonged, intense cold. In very cold climates, it can be grown indoors or covered with mulch.

3. Irrigation and humidity

• Regular watering, keeping the substrate moist but never waterlogged. Wait for the surface layer to dry slightly between waterings. In humid environments, the importance of fronds in their development also influences your care.
• In spring and summer, increase watering frequency based on evaporation and ambient heat; in autumn and winter, reduce the dose to avoid excess moisture.
• Humidity: The fern needs a humid environment to keep the fronds green and healthy, so it is recommended to spray the leaves with water (without lime) especially in warm weather or in dry environments.
• Avoid wetting the rhizome directly, as waterlogging can cause rot.

4. Substrate and transplant

• Ideal soil: Rich in organic matter, loose, spongy, and well-drained, preferably with an acidic pH (3.5 to 5.5). It does not thrive in compact or highly calcareous soils.
• For pot cultivation, a mixture of leaf soil, peat, and coarse sand is ideal. Powdered charcoal can be added to improve structure and prevent fungal diseases.
• If grown outdoors, the soil must allow for good drainage to avoid waterlogging. It tolerates poor substrates if adequate moisture is present.
• Transplant: The fern doesn't tolerate frequent changes of location well. If repotting is necessary, do so in early spring and avoid excessive manipulation of the rhizome. Only change the substrate if the plant still has room for roots.

5. Fertilization

• Polypodium vulgare requires very little fertilizerDuring active growth (spring and summer), you can apply liquid fern fertilizer every 4-6 weeks, always diluted if the substrate is poor. For more details on feeding your plants, see properties and care of maca.
• Avoid fertilizing during the winter dormant period.

6. Pruning and maintenance

• Remove dry, yellowish, or damaged fronds at any time of the year to promote regeneration and prevent disease.
• The plant does not need structural pruning.

7. Control of pests and diseases

• Polypodium vulgare is very resistant to pests and diseases. It may occasionally be attacked by mealybugs, especially indoors with poor ventilation.
• To control mealybugs, clean the leaves with a cotton ball soaked in alcohol or use potassium soap or organic insecticides.
• Fungus and dark spots can appear due to excess moisture. In this case, reduce watering, improve drainage, and use fungicides.
• Prevention: Avoid sudden changes in temperature, maintain good air circulation and do not use foliar polishes.

Multiplication and reproduction of sweet fern

Polypodium vulgare can be multiplied in two main ways:

1. Division of the rhizome: A practical and effective method. It is carried out in early spring by cutting rhizome segments with at least one healthy frond. Place in a substrate of equal parts peat and sand and store in a warm, moist environment until rooting takes place.
2. Spore sowing: Advanced and less common method. Take mature spore-bearing fronds and place them on moist peat substrate, covering them with glass or clear plastic to maintain humidity. Patience is required, as it can take months for seedlings to emerge. Once grown, transplant them into small pots.

Ornamental uses and gardening applications

Thanks to its adaptability and attractive foliage, the sweet fern is highly valued for various landscaping projects:

• Interior decoration: Ideal for hanging baskets, terrariums, shade gardens, or as a background plant in rooms with indirect light. Its foliage adds a fresh, natural feel to any indoor space.
• Vertical gardens and green walls: Excellent option for covering vertical surfaces thanks to its epiphytic nature, allowing for artistic and ecological compositions.
• Soil stabilization and environmental restoration: Its root system helps prevent erosion on slopes and inclines, consolidating vulnerable soils.
• Landscape composition: It combines well with other shade species such as hostas, begonias, Japanese painted fern, mosses, hydrangeas and ivy.
• Borders and rockeries: It blends perfectly into path edges, between rocks or old walls, and wet areas of the garden.
• Living centerpieces: Due to its compact size and ornamental foliage, the sweet fern is ideal for temporary arrangements at events and gatherings.

Frequently asked questions about Polypodium vulgare

• Is sweet fern toxic? It is not considered toxic to people or pets, although its consumption should be limited to traditional uses and under professional advice in natural health.
• Can it live only indoors? Yes, as long as it receives sufficient humidity and indirect light, the sweet fern adapts well to indoor cultivation.
• How long does it take to grow? Its development is relatively slow, but once established, it can form dense and resistant carpets.

• Non-flowering cycle: Polypodium vulgare does not develop flowers; its reproductive cycle depends on spore production, a mechanism present in all ferns.
• Biological resistance: It can survive adverse conditions thanks to its rhizome, which stores nutrients and allows it to regrow after dry or cold periods.
• Ecological importance: Create microhabitats for insects and small animal species, contributing to the biodiversity of the environment.
• Etymology and culture: The term "polypodium" refers to its branched, tentacle-like roots, evoking its ability to attach and colonize.

Recommendations and warnings for use

• Medicinal use of the rhizome should be carried out under the supervision of a specialist, to avoid side effects or unwanted interactions.
• Do not use foliar polishes or harsh chemicals, as they can clog stomata and affect plant physiology.
• Keep the fern away from cold drafts and sudden changes in temperature.

Growing and caring for Polypodium vulgare offers a rewarding experience both ornamentally and medicinally, bringing beauty, utility, and resilience to gardens and interior spaces. Its maintenance is simple, and its history, linked to traditional knowledge, makes it a versatile ally for those seeking low-maintenance plants that are respectful of the environment and full of natural symbolism.