How to Care for the Giant Leather Fern

As a huge fan of tropical plants and flowers, one of my favorite places to visit is Key West, Florida. In addition to having loads of flora and fauna in the garden settings and at resorts, it’s also found everywhere in the wild! It’s an absolute dream to find Birds of Paradise growing in abandoned lots and Bananas popping up at gas stations. One of the understory plants that I fell in absolute love with was the Giant Leather Fern.

You may think that you’ve seen big ferns before, but let me tell you, the Ostrich has nothing on this bad boy! The Giant Leather Fern is the KING OF FERNS! It’s a mammoth Fern with huge but still dainty looking fronds that are shiny on the top side. They are perhaps even more attractive than the lacy and feathery Ferns your mom grew, but ten times the size. Caring for a Giant Leather Fern isn’t difficult, but they do have certain requirements that there’s no getting around. Read on to discover how you too can grow these prehistoric giants, outside of the tropics!

About Giant Leather Fern

The Giant Leather Fern aka Acrostichum danaeifolium, is considered a marsh or bog plant. There are several members of the Pteridaceae family and all are considered Leather Ferns, including danaeifolium. Mature plants have a distinct collection of spores on the undersides of each leaf, giving a two-toned appearance of brown and green-fertile and infertile fronds.

It’s a native to areas like Mexico, Central America, South America, Brazil, the Caribbean, and of course, Florida. While it grows naturally in freshwater settings, it is also very salt tolerant. It can reach a height and width of 12′ when mature! My personal fern is a mere baby, and reached a height and width of 4′ by the end of summer!

Here’s another great post that details these Florida natives.

Sun Requirements

Unlike many ferns, the Giant Leather Fern enjoys full sun in most parts of the country! Here in the South, I give mine a shaded environment, but only because I can’t plant it in the ground due to its winter hardiness, or lack thereof. It can tolerate lower light levels, as well, although I’ve found that it doesn’t grow as quickly as what it would do in Florida. You’re going to need a really big container because it spits out new fronds on a weekly basis. The easiest thing to do would be to position it in a morning sun location or underneath a shade tree that allows filtered light.

Water & Humidity Requirements

Lots. I can’t stress this enough. It’s a bog plant, so just like the Papyrus you love to grow, the Giant Leather Fern demands wet feet. I have somewhat tested this theory and while it can survive short periods of going without water at the top level of soil, I found that I’d lose a frond or two. Luckily, it bounces back nicely, but I’ve never once allowed the underground rhizomes to get completely dry. It doesn’t have to be sitting in water, but the soil must stay adequately damp.

This plant really digs humidity, as well. I might be the only Texan that will say we were fortunate to experience really high humidity this past summer. During dryer summers, I’ll have to make a point to crowd the Fern amongst other plants and water daily to retain a level of high humidity. Southern sun in a container can absolutely wreck this beautiful plant if you’re not careful.

Soil Requirements

In its natural environment, the Giant Leather Fern grows in organic-rich swampland. Because here in Texas I have to grow it in a container, I made good use of Black Cow, and soil that contained bark pieces to retain moisture. The soil should be loose and airy, so mixing in pebbles is a good idea. The idea is to create a moisture-retentive mix, which can easily be achieved by adding organic matter to the soil. If you live in warmer parts of the country, feel free to plant these puppies straight into the ground and keep them well-watered!

Food Requirements

When growing the Giant Leather Fern outside of a pond or bog setting, it’s important to feed it every now and then. I never go nuts here, but I do offer mine food several times per season. I alternated between Seaweed/Fish Emulsion mix and Miracle-Gro. Being that it’s a bog plant, you must keep in mind that it receives many nutrients from the water it grows near. Ferns of all types love regular feedings and will grow faster and fuller with them, but will survive without them if times are tough or you get really busy.

Pruning

It’s important to remove dead or dying fronds, as close to the base as possible, to force the plant to send all of its energy into growing new fronds or strengthening the living fronds. The Giant Leather Ferns grow in a large vase-like clump, and sometimes need to be pruned to keep from being heavy on one side. Other than trimming away dead foliage, however, pruning is strictly cosmetic. The plant grows upright nicely without any help.

We did experience a strong storm that sent 50 mph winds straight at my Fern. A few of the fronds snapped into and had to be removed. Unfortunately, I didn’t get photos of my thriving summer Fern prior to the storm, which is why it appears to have sparse foliage. Trust me, this Fern forms a perfect vase and looks extremely full when it doesn’t have Mother Nature taking it out.

Propagation

Obviously the Giant Leather Fern can be reproduced by propagating spores, if you have the perfect environment, or dividing the underground rhizomes.

Problems

Here’s a great post detailing potential diseases associated with the Giant Leather Fern. I haven’t personally dealt with any diseases (knock on wood) so I don’t have a lot of input outside of this post. However, when it comes to fungal diseases, I recommend Spectracide. As far as insects go, I’ve had a bit of experience with that. This past summer we had a few pest problems in our test gardens that drove me insane. I felt like I was fighting insects at every turn.

Scale insects and slugs are the main problem pests associated with the Giant Leather Fern. For major infestations, I use Sevin and of course, for routine use, I turn to Raid House and Garden. I did fight with slugs a bit, as well as Spider Mite. It was all very manageable, but due to the damp and humid conditions this past summer, the bugs did enjoy munching on the Leather Fern from time to time.

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Winter Hardiness/Overwintering

The Giant Leather Fern is only hardy to about 15 degrees, so growing outside is ruled out for the majority of us. At first, I brought my Leather Fern indoors. This proved to be a big mistake for two reasons – not enough light and the heater sucked the moisture out of the container way too fast. If you have a sunny position in your home and you are an avid waterer, then you shouldn’t have the same problems. My home is filled to the brim with plants and the sunny locations were already too crowded for a plant the size of the Leather Fern.

I moved it into the garage. Not only does it benefit from a window, and the overhead light (that stays on constantly), but I could also move it outdoors on particularly warm days, easily. We do keep a space heater in the garage and run it on evenings where the temps drop to near freezing. It would also do well on a heated patio during the winter months, a greenhouse, or a glasshouse.

While I won’t say it’s impossible to grow indoors, it won’t grow properly without water, heat, and humidity. The Giant Leather Fern would also do nicely in a closet with a grow lamp if you have the room or in front of a window surrounded by other plants for humidity. Since it receives more light in the garage, and the space heater doesn’t draw moisture from the container too quickly, my Giant Leather Fern is much happier there. It’s also easier to water in the garage. On warmer days, I simply water my plants with a hose, which is quick and painless and keeps the garage nice and humid. While I’ve certainly lost a few fronds in all of my trial and error, it’s also growing new fronds from the base. Come summer, it’ll be giant again in no time, and I’ll know better for next year.

Uses

I can think of dozens of uses for the garden landscape! The Giant Leather Fern looks fabulous, even in a container, around pools or ponds. It makes a wonderful focal piece at the back of a flowerbed or underneath a shade tree. It’s eye-catching size and gorgeous, shiny fronds make it an extremely versatile plant to use in both formal or jungle-styled gardens. This is an architectural masterpiece in the making, and whether you intend for it or not, it will stand out and scream, LOOK AT ME!

Just keep in mind that it does get mega big and will need a large container to fill out properly. Mine is planted in a ten-gallon nursery grade container. Because it is top-heavy, you’ll want a container with a bit of meat to it, and of course, keep that soil nice and damp. This Fern looks otherworldly when it is at its best! I can totally envision dinosaurs walking amongst these beauties.

While my Fern is still a baby by all measures, it’s already an imposing garden specimen! I adore the two-toned look of the mature Ferns, and can’t wait to get there. For a really massive and striking plant, try incorporating a Giant Leather Fern into your landscape design. You almost never come across this outside of Florida or the tropics, so you’ll be sure to have a unique focal point that’ll stun passerbyers (yes, I invented a word)!

Fern lovers know, there’s little else that commands attention in the garden like a large and healthy Fern. So it’s not hard to imagine how spectacular the sight of the world’s largest Fern will be! Try it and see!

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