Carrot Fern (Onychium japonicum)

Carrot fern (Onychium japonicum) is a deciduous, perennial fern that gets its common name from its lovely feathery fronds, which look like the foliage on a carrot. It thrives in shade and does well under trees and in a shade garden. It prefers moist, well-drained soil. If planted outdoors, use mulch to protect the roots in winter.

I. Appearance and Characteristics 

Onychium japonicum is a species of fern in the family Pteridaceae.

The species was first described in 1784 by Carl Peter Thunberg as Trichomanes japonicum. In 1825, Blume used the name “Onychium” for a genus of orchids, but this was illegitimate since it had been used in 1820 for the fern genus. Blume also used the combination “Onychium japonicum” for an orchid (now Dendrobium moniliforme). In 1848, Kunze transferred Trichomanes japonicum to the fern genus Onychium as Onychium japonicum. The name Onychium japonicum (Thunb.) Kunze is conserved against Onychium japonicum Blume.

II. How to Grow and Care

Carrot fern is generally considered an easy-to-care-for orchid, suitable for both novice and experienced gardeners. It thrives in bright, indirect light and requires a well-draining potting medium, such as a specialized orchid mix. Special care points include maintaining a consistent watering schedule, allowing the medium to dry slightly between waterings, and providing high humidity without letting water accumulate at the base, which can lead to root rot.

Sunlight

Carrot fern thrives under partial sun conditions, where it can bask in gentle, filtered light, ideal for its vibrant growth and blooms. Exceeding or reducing these light levels can lead to poor vigor and diminished flowering. The plant exhibits resilience, however, subtle leaf color variations may signal light-related stress. When grown indoors, an east or west-facing window offers a perfect balance, mimicking its natural dappled light habitat. Outdoors, placement in areas with morning sun and afternoon shade or beneath a canopy ensures the right light exposure for carrot fern’s optimal performance.

Temperature

Orchid plants are native to tropical and subtropical regions, preferring warm, moist conditions. Optimum growth temperatures are between 18 to 28 ℃, and it’s best if there is a certain difference in temperature between day and night: for example, 20 to 25 ℃ during the day and 15 to 18 ℃ at night. Carrot fern is a drought-tolerant plant, but cannot tolerate waterlogging, and grows well at 50-70% humidity. If the leaf tips are withered, it means the environment is too dry. Use a humidifier or spray bottle to increase the air humidity.

Watering

Native to humid forest environments, carrot fern thrives with consistent moisture and high humidity. This species exhibits a preference for regular hydration but can endure short periods of dryness. It’s best to maintain a watering schedule of twice a week to mimic its natural conditions. As an epiphytic orchid often grown indoors, carrot fern benefits from occasional misting to replicate the moist air of its tropical origins, which is essential during its active growing season.

Soil

The “soil” required for carrot fern is special because, as an epiphyte, it originally grew on big trees in tropical forests. You need to mimic this growing environment with, for example, water moss, wood chips, coconut shells, volcanic stones, or perlite as soil substrate. You can also buy orchid-specific soil directly from gardening stores.

Fertilizing

For optimal growth, fertilize carrot fern monthly with balanced nutrition fertilizers during growth periods, less in winter. High phosphorus fertilizers enhance blooming. Use dilute solutions to prevent root burn. Seasonally adjust: increase frequency when actively growing and reduce in dormancy. Practical tip: water before fertilizing to aid nutrient absorption and minimize root damage.

Planting Instructions

You do not need a large pot to grow an carrot fern as it won’t produce a vigorous root system that occupies much space. If the pot is too large, the soil tends to collect water and cause root rot. The height of the pot should be 2.5 cm taller than the (pseudo)bulb of the carrot fern. You can easily buy carrot fern in a local gardening store and simply place it in breathable, well-drained substrate. After planting, use upright sticks to support flowering branches. In warm, humid climates, cover the root of carrot fern with sphagnum moss and attach them to a tree with strings.

Pruning

It is best to prune wilted carrot fern flowers promptly after blooming to reduce unnecessary nutrient consumption and promote more blooms. Trim withered and diseased leaves promptly to increase air circulation, thus reducing pests and diseases.

Propagation

Carrot fern is known for its ease of propagation through division. Gardeners should gently separate the pseudobulbs, ensuring each division has at least one growth point. The sections can then be potted into an appropriate orchid-growing substrate, providing moderate light and humidity to foster growth. Careful monitoring for pests and diseases is crucial during early establishment to ensure successful rooting and development of new shoots.

Transplanting

For carrot fern, Spring and early Summer (S3-S5) are the best times to transplant, ensuring optimal growth in the budding season. Choose spots with ample sunlight and well-drained soil. Remember, with carrot fern, a gentle touch during transplantation is beneficial!

III. Harvesting and Storage

If you want to display carrot fern flowers in vases, harvest there are only 2-3 flowers blooming on the stem. Cut diagonally at the bottom of the flower stem, and place it in a vase immediately. You can enjoy the cut flower in clean water for about 14 days, or for a longer time with preservatives.