Harvest Instructions:

Plants grown at 68F day, 60 night temperatures lasted 36% longer compared to those grown at 86F day, 77F night temperatures. Fronds harvested from tissue cultured propagated cultivars generally last longer than those not from tissue culture. On average, larger size fronds tend to not last as long as smaller size ones harvested from the same cultivars. Most leatherleaf is dipped after harvest in various mixtures of water, mineral oil and surfactant to both clean and hopefully extend subsequent vaselife. Commercial products sold for this purpose include Hydroseal, Pixie Sparkle or Saf-T-Foliage. When vaselife is naturally two weeks or longer for non-treated fronds, these treatments add little value. However, vaselife can be significantly extend up to nearly 300% when dipped in these solutions at times of the year when non-treated fronds last less than two weeks. Fronds produced under high night temperature (77F) did not last as long as ones produced at 60F. High percentages of urea containing fertiliers should not be used with this species as decreased yield and quality are likely.

Leatherleaf Fern Care

Leatherleaf fern (Rumohra adiantiformis) produces sturdy, glossy dark green fronds that work well when incorporated into flower arrangements. The evergreen fern is equally beautiful when grown in a garden or inside, where its lush fronds can add some much-needed texture and greenery in shady or low-light sites. This attractive fern requires minimal care to look its best.

Choose a Shady Site

Leatherleaf is a frost-tender fern hardy in U.S. Department of Agriculture plant hardiness zones 9B to 11, where it can handle temperatures as low as 25 degrees Fahrenheit. The fern requires a site with partial, shifting or deep shade, and it will suffer in direct sunlight. If planting multiple ferns, provide 24 to 36 inches of space between plants to avoid overcrowding.

Organic Soil is Best

Leatherleaf fern tolerates a range of soil types, though like other ferns it grows best in soil enhanced with organic matter. Mixing 2 inches of composted pine bark into the soil can improve both heavy clay soils and sandy soils.

Water regularly during the growing season in the garden, allowing the soil to slightly dry out between waterings. Mulch in spring and fall with 2 to 3 inches of organic matter such as pine straw or leaves to maintain moisture in the soil and suppress competitive weeds.

Grow Indoors Where Not Hardy

Leatherleaf fern may be grown indoors in indirect sunlight, such as a north-facing windowsill, in colder climates. Avoid placing the fern near heating vents or south- or west-facing windows as these conditions may scorch the fronds. Choose a container with a hole in the bottom for drainage and soil-less potting mix that is 50 percent peat moss.

Water occasionally, allowing potting media to slightly dry out between waterings. Leatheleaf fern does not have high humidity requirements and does not need to be misted. Fertilize every four to six weeks during the growing season with 3 1/2 to 7 drops of a 10-10-10 fertilizer mixed into 1 quart of water. Repot every few years in the spring, replanting in fresh potting media. Divide large plants by carefully splitting the rhizomes.

Check for Pests

Leatherleaf fern may attract common pests such as scale, hard or soft-shelled insects that form dense colonies on fronds; mealybugs, cottony white insects; and mites, tiny, spider-like insects. Outdoor plants may attract slugs and snails. Handpick insects as they appear or wash fronds with a direct stream of water. Cut off fronds infested with scale. Drown slugs and snails in soapy water.

Avoid pesticides, which may burn the sensitive fronds. Monitor the fern every week or so to see if pests re-emerge. House plants that are heavily infested may need to be discarded before the pests spread to healthy plants.

Treat for Blights

Several fungal blights affect leatherleaf ferns. Anthracnose or Colletotrichum Blight affects new growth on the fern, with older fronds not easily infected by the disease. New growth becomes black and further development ceases. Rhizoctonia Aerial Blight occurs most often during summer, with the fronds covered in gray or brown spots that eventually travel up the center where moisture levels are highest. Control the problem by keeping old fronds pruned to increase the circulation of air. Always use sterilized pruning tools when pruning the fern, by wiping the blades off with alcohol and allowing to dry before use.

Treating both fungal diseases with a product containing Daconil helps control outbreaks. Mix 2 1/2 tsp. of Daconil into a sprayer containing one gallon of water. Thoroughly cover all sides of the foliage until dripping. So the fern’s foliage isn’t damaged, do not spray when temperatures are above 90 degrees Fahrenheit or during sunny conditions. Wear a long-sleeved shirt, gloves and safety glasses when using and wash hands immediately after use and keep children and pets out of the area until the product has dried.

Control Root Rot and Leaf Spots

Pythium root rot can be problematic for leatherleaf ferns grown in areas with improper drainage. Infected ferns become limp and turn a green-gray in color and the roots stop growing and turn to brown mush. The problem is most likely to occur during winters where rains are excessive. To control the problem, grow the fern in soils that are not soggy and drain well.

Cylindrocladium leaf spot is most likely to affect leatherleaf ferns during summer or when winters are warm. Red or brown-gray spots up to an inch in size cover most of the frond and can have a water-soaked appearance. Control the disease naturally by watering early enough in the day so the fronds dry by nighttime. If the problem is serious, treat the fern with the same Daconil treatment as you would with blights.

Rumohra adiantiformis is a fern species from the family Dryopteridaceae. It is native to a diverse range of countries in the Caribbean, South America, southern Africa, Australasia, Papua New Guinea, and islands in the West Indian Ocean.

The plant is typically grown in gardens as well as indoors.

Common names include:

  • Leather Fern
  • Leather-leaf Fern
  • Leathery Shield Fern
  • Iron Fern
  • 7-weeks Fern

Size & Growth

Rumohra adiantiformis is an evergreen herbaceous fern species growing up to 2’ – 4’ feet depending on the growing conditions.

The dark green-colored, lacy-looking, finely-cut, glossy, and triangular-shaped fronds give the plant a tropical appearance.

A feature of leather leaf distinguishing it from most other fern species is it does not have separate reproductive fronds.

Instead, the reproductive clusters, called sori, are located on the underside of the leaflets.

Since the fern species spreads slowly, it is suitable for growing in small spaces, pots, and hanging baskets as well.

When grown outdoors, make sure to leave 24” – 36” inches of space between each fern.

The fern is hardy to USDA hardiness zones 9-11.

Flowering and Fragrance

Since Rumohra is a fern species, it does not produce any flowers.

Evergreen year-round.

Holds its deep green color and frond integrity under less-than-ideal circumstances.

Light & Temperature

Adiantiformis prefers a partial shade position with filtered sunlight.

While the plant can survive in full shade, it cannot tolerate full sun and direct sunlight, so be careful not to expose your plant to full and direct sun.

Outdoors, leatherleaf ferns grow best in shady areas but inside will take bright, indirect light.

The plant cannot tolerate temperatures below 24° degrees Fahrenheit (-4° C), so avoid planting them outdoors if you live in an area where the temperature falls below this during winters.

USDA hardiness zone 9 – 11.

Watering and Feeding

Though they are not particularly high-maintenance, leatherleaf ferns do have specific light, soil and water requirements.

While rumohra adiantiformis plants need regular watering to thrive, they can survive with less frequent watering after they are fully established.

However, do not let them completely dry out as they only have moderate drought tolerance.

The plants are also intolerant to water with a high mineral concentration or is salty.

Fertilizing the plant with a half-strength liquid fertilizer once a month, during the growing season, helps to maintain the color and shine of its foliage.

The frequency and amount of the fertilizer vary according to the type of soil the ferns are planted in.

Do not apply fertilizer to the transplanted rhizomes until they start developing feeder roots.

Soil & Transplanting

The houseplant fern species can grow in loam, clay, or sand, but the soil has to be rich in organic matter, moist, and well-draining.

Expert planters suggest to top-mulch the plant periodically for best results.

It also prefers acidic soil.

Grooming and Maintenance

The fern is a low maintenance plant and doesn’t require much effort from your side.

Cut the old fronds down to the ground with a sharp knife in spring just as the new growth appears.

You may also like the Ghost Fern – Athyrium Hybrida

How To Propagate Leather Fern

Propagation of leather-leaf fern is performed through spores or rhizome divisions; however, the latter method is mostly preferred by non-commercial planters.

Take about 3” – 5” inches long terminal rhizome cuttings at the beginning of the plant’s growing cycle, in spring, and plant them in separately in potting filled with sterile and well-draining soil.

For best results, include a few leathery fronds in the rhizome cuttings; it improves the ability of rhizome divisions to take roots.

While the leather-leaf fern propagates naturally through spores in mid-summer, the spores are collected and sown by gardeners.

Propagation from spores is done by sowing them on the surface of a sterilized and moist growing medium.

A mixture made from equal parts of loam, coarse sand, peat, and leaf mold is considered the best for growing rumohra adiantiformis through spores.

Iron Fern Pest or Diseases

Leather fern plants can get affected by:

  • Mites
  • Scale insects
  • Fern borers
  • Leaf miners
  • Mealy-bugs
  • Leafhoppers

The plant is also susceptible to fungal diseases, but most of them are prevented by using sterile tools and growing mediums.

You may also consider applying a fungicide in established plants.

Excessive watering and poor drainage may cause root rot, which then can affect the color of the foliage and may also cause wilting.

Uses For Rumohra Leather Leaf

Rumohra adiantiformis is cultivated as an ornamental plant, mainly as a groundcover, and is also widely used in floral arrangements due to the longevity of its fronds.

The fern species has significant economic importance in Brazil – a large number of local people earn money by wild-harvesting and selling the fronds.

Seasonal variations in production and development of leather leaf fern leaves1

Production and development of leatherleaf fern leaves were studied using containerised plants growing in a shade house. Leaf development was partitioned into seven arbitrary development stages; the time needed for leaves to progress through each developmental stage was used to measure days required to reach maturity. Measurements were made twice each week throughout 1997. Means and variances with in emergence rates of new leaves and time needed for new leaves to pass through six leaf development stages were calculated for 26 14‐day periods throughout the year and compared with degree days, solar radiation, soil temperature, and daylight hours accumulated during the periods. Leaf production rates ranged from 0.15–0.73 leaves day−1 plant−1. The average time from emergence to maturity was 22.6 days. Both leaf production and development rates varied greatly with the seasons, and were strongly associated with the weather variables measured, but significant cyclic rate fluctuations unrelated to weather were also detected. Leaf emergence rates were more strongly related to average soil temperature, whereas leaf development rates to maturity were more strongly related to solar radiation and degree days.

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