House Holly Fern (Cyrtomium falcatum)

Holly fern (Cyrtomium falcatum), named for its serrated, sharp-tipped, holly-like leaves, is one of the few plants that will grow happily in the dark corners of your garden. When planted in a flower bed, the lush, deep green foliage provides beautiful contrast as a background for colorful annuals and perennials. Read on to learn about the care of holly ferns.

I. Appearance and Characteristics 

Cyrtomium falcatum is a species of fern, commonly known as house holly-fern and Japanese holly fern, in the wood fern family Dryopteridaceae. It is native to eastern Asia.

It grows from crevices in coastal cliffs, stream banks, rocky slopes, and other moist, stable areas.

This fern is a perennial plant with a large light brown rhizome.

Cyrtomium falcatum has leaves exceeding 0.5 meters (1.6 ft) in length made up of six to ten pairs of shiny bright green leaflets. Each leathery leaflet has a flat to wavy to slightly toothed margin and a netlike pattern of veining. The underside of each leaflet has sori beneath brown or black indusia.

Cyrtomium falcatum is a popular ornamental plant in temperate climate gardens (zones 7 to 10), and is also popular as a houseplant. It is hardier than most ferns; it thrives in light shade to deep shade with average fern soil. It is easily and quickly propagated by spores, but it can also be propagated by rhizome division.

This plant has gained the Royal Horticultural Society’s Award of Garden Merit.

The fern has escaped from cultivation on other continents and has become established in the wild as an introduced species. It can now be found in much of Europe, North America, the Atlantic Islands, Australia, New Zealand, and South America.

II. How to Grow and Care

The Cyrtomium falcatum Holly Fern is a perennial plant that grows a light brown rhizome covered with fuzzy hairs.

On the underside of the leaflets, you notice the black or brown sori and produce spores that start greenish and turn a light brown.

The Holly Fern is more for ornamental display as it does not flower. Even caring for the Japanese Holly Fern is a breeze, as you will see here.

Sunlight

When you grow your plant in woodland gardens, it prefers a shade garden. Hence, it helps grow your Holly Fern with other ferns that enjoy filtered bright light. It can tolerate full shade for a short time.

When growing in a container indoors, we recommend providing your plant with bright indirect sunlight but not too much direct sun as it can burn the fronds.

Temperature and Humidity 

The Japanese Holly Fern can thrive in typical room temperatures in the home well. But your plant will need higher humidity, and placing it in a bathroom is excellent. Or you can keep a pebble tray filled with water underneath it.

Still, remember that the roots should not touch the water leading to wet feet.

Watering

The Cyrtomium falcatum Holly Fern prefers dampened peat moss compared to other ferns. Thus, if you grow it outside, you can reduce watering with frequent rain. Also, please wait for the soil moisture to dry before watering as it can lead to root ball rot when overwatered.

If your Japanese Holly Fern grows indoors, it does not need a winter resting period. But if grown outdoors, it helps provide your plant with rich humus-rich soil with some mulch for overwintering.

We recommend keeping it in partial shade with moist soil in warm climates.

Soil

Your Holly Fern has an extensive root system and needs moist, well-drained, and slightly acidic soil to grow its best. Making the soil more fertile helps add some organic matter to the mix.

We recommend adding some mulch in winter to keep the roots protected when grown as an outdoor plant. But this is not such a big concern grown indoors.

The best time to repot your Cyrtomium falcatum is early spring when the growth begins. You can choose a larger pot and use a mixture of coarse peat moss with half-leaf mold.

Fertilizing

When your fern is still young, you can provide them with a liquid fertilizer every two weeks. The best time to transplant your fern indoor plant is in spring. Once repotted and it starts to show new growth, you can use a diluted slow-release feed.

Or you can feed your plant with fish emulsion as well. But please try not to overfeed.

Grooming 

Okay, caring for your Holly Fern is done without any fuss as it can tolerate gas fumes, dry air, and low light better than other ferns. The only thing it cannot handle is soggy soil and icy temperatures, as it can lead to winter-damaged fronds.

You will notice shedding during the harsh cold season, but it starts to thrive in the growing season when warmer. You only need to give it some grooming to remove the frayed or unsightly foliage.

Once you cut the fronds, they will regrow but take extra care not to snip into the crown.

Propagation

The fastest way to propagate Cyrtomium falcatum is using the division method in spring. First, water deeply the day before you remove it from the container. Next, you pull the rhizomes apart with one that has green fronds and divide them into three sections.

Replant the divided sections into a pot with drainage holes and fast-draining soil. To retain moisture, you can mist your plants until new growth appears. Once developed, you can transplant them into the garden or bigger pots.

Another technique is using the spores on the underside of the fronds. Once you see them ripen, you will notice them open up with a dust-like spore falling out. You can collect the spores by removing them from the leaves.

Then place it pore-side down on wax paper and leave it until the spores stick on the paper. Or you can put it in a plastic bag and give it a good shake. Next, prepare a small pot with damp peat moss and transfer the spores into the soil line.

Then close it with a plastic wrap or lid and keep it in bright indirect light until it sprouts new plants.

Repotting

Holly Fern grows most quickly in the summer, so it should be planted again in the spring. When repotting, make sure the plant’s crown is just above the soil line to avoid rot. Use a pot with drainage holes that is 5 cm larger than the previous one to prevent the soil from becoming soggy. If you want to divide your fern after removing it from its container, this is a good time to do so.

Pests and Diseases

• Yellowing foliage and wilting: This is a clear symptom of overwatering in your fern. The Holly ferns prefer evenly moist soil with good drainage and won’t tolerate a potting medium that is excessively soggy. Before watering, check the moisture content of your potting soil, and make sure the top 2-4 cm of soil are completely dry before watering again.  For more details on identifying Over vs Underwatering, read this.
• Wilted foliage and dry fronds: This is a sign that you’re not watering your fern enough. Be sure to keep the soil evenly moist and to water as soon has the potting soil is reaching dryness. Do not allow your fern to dry out, even though it can tolerate it. Long periods of dryness will lead to crisp leaves and wilt.
• Leaves turning silver: If you see your Holly ferns’ foliage beginning to turn silver, take the surrounding temperature into account. Heat stress, which can result from being placed on hot surfaces like brick or in direct sunlight-exposed ceramic planters, is what causes silvering foliage. Placement near a heater, fireplace, or radiator are some additional sources of heat. Relocate to a cooler space.
• Crisp dry patches on leaves: These patches are caused by scorching from sunlight. Be sure not to expose your plant to direct sunlight, and keep away from the window sill, where the glass can act as a magnifying glass.
• Wet brown patches on leaves: Wet brown and sometimes smelly patches are caused by bacterial or fungal growth. This usually occurs when moisture sits on the foliage for long periods of time. So avoid this, spritz your plant early in the morning to allow time for rapid evaporation, and provide good air circulation around the plant. Remove any infected leaves and discard in the bin to avoid spread. You can also treat the infection with a Fungicide such as Copper Soap.
• Ferns’ outer tips are turning brown: This is an indication that your plant may be suffering from over fertilization or being exposed to dry air. Ferns prefer a very weak dilution of feed and do not need regular feeding. If you are feeding on a weekly basis, rather reduce the frequency to a bi-weekly rotation. If feeding is not the cause, consider the humidity in the space you are in. The hotter the room the drier the air, thus raising humidity by placing your Fern on a pebble tray or relocating to a more humid location such as your bathroom.  
• Pests: Japanese Holly ferns don’t usually get pests, but if you don’t take care of your plant and keep it in good shape, it may get stressed. Stress will lead to pest infestations, causing excessive leaf discolouration and leaf drop. Mealybugs are the most common indoor plant pest that will attack your Fern due to high humidity environments. If you don’t treat them, they can weaken your plant quickly. Adjust environmental stressors for your house plant and treat infestations with an organic pesticide such as Pyrol.

III. Uses and Benefits 

The holly-like appearance and evergreen foliage of house holly fern create an interesting texture in woodland gardens, especially when planted en masse. Many people plant this species together in shady gardens sites with other varieties of holly to juxtapose and contrast the different and shapes of the plants.