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Ferns are among the most diverse and beautiful plant groups on the planet. There are hundreds of different species. We often think of ferns as being shade-lovers, and while many are, there are also many others that thrive in full sun. In addition to growing ferns in an outdoor garden, several warm-climate species of ferns also can be grown indoors as houseplants. This article is about one of today’s most popular species of ferns for indoor growing: The blue star fern (Phlebodium aureum).
Meet the blue star fern
While you might think ferns are nothing more than a simple plant with a feather-like leaf structure, nothing could be further from the truth. Ferns are among the oldest living plants in the world. They evolved hundreds of millions of years ago (eons before the dinosaurs) and continue to thrive here today. Unlike flowering plants, ferns reproduce by spores, not seeds, and they have a very complex lifecycle. For certain, not every fern grower is interested in learning the intricate details of fern botany, but if you are, we recommend the book The Complete Book of Ferns by Mobee Weinstein of the New York Botanical Garden.
The diversity of leaf structures of ferns might surprise you. In the fern world, their leaves are called fronds. While green, feather-like fronds are what likely come to mind when someone says the word “fern”, this plant group has a surprising array of frond structures and colors.
Case in point: the blue star fern. This species has bluish-gray fronds that are deeply lobed and quite irregular in shape. When the plant is young, the fronds are uneven in size and shape, and they grow from the base of the plant in a random pattern. As the plant matures, it develops larger fronds with a more uniform and consistent structure. If you look at them closely, this fern’s fronds are covered in tiny hairlike structures.
How to care for a blue star fern
At maturity in its native habitat, a blue star fern tops out at 2 feet in height, sometimes taller. It grows wild in tropical and subtropical regions of North and South America, preferring warm temperatures to cold. This species is hardy only down to 20 degrees F.
A blue star fern thrives in drier, less humid conditions than most other fern species, making it an ideal houseplant. It also grows in more light than many other ferns. Choose a window with bright, indirect light. Near an east- or west-facing window is best.
The best soil and pot for a blue star fern
Unlike some other ferns grown as houseplants, the blue star fern prefers a specific type of potting mix rather than just a general one. Choose a houseplant-specific potting mix and then add a few tablespoons of perlite to it to improve the drainage. In their native habitat, blue star ferns are epiphytes, meaning they grow with their rhizomes (modified horizontal stems) attached to tree branches, rather than growing down into the soil. However, in the environment of a home, you shouldn’t expect to grow them successfully in orchid bark or another epiphyte-specific mix because it dries out too quickly.
Choose a pot with a drainage hole in the bottom, but do not use terra cotta. Instead, use a plastic pot or a glazed ceramic container to grow this fern. Terra cotta (clay) dries out much too quickly for the blue star fern.
How to water a blue star fern
The potting soil should be kept consistently moist but not wet. It’s best to move your blue star fern to a sink or bathtub for watering. When the soil is dry to the touch, pour a steady but slow stream of room temperature water into the top of the pot. Allow the water to continually flush through the potting soil for a few minutes, then let the pot sit in the sink or tub until no more water exits the drainage hole. After it has fully drained, it’s time to put your blue star fern back on display. If you have a saucer beneath the pot, make sure it is empty and does not contain standing water which can lead to root rot.
There is no need to mist this fern or place it on a humidity tray. Blue star ferns don’t favor high humidity quite as much as some other fern species.
Your fern receives the nutrients it needs from new potting soil for six to eight months after planting, but once that time period has passed, the nutrients in the potting soil have likely been depleted. Now it’s time to fertilize.
Use a houseplant-specific liquid or granular fertilizer from early spring through early autumn. Mix liquid fertilizers with water at half the strength recommended on the package and apply once a month. For granular fertilizers, sprinkle ½ to 1 teaspoon on the top of the soil every 6 to 8 weeks. I prefer organic fertilizers to those based on synthetic chemicals, but the choice is yours. Do not fertilize a blue star fern in the winter when it’s not actively growing. Over-fertilization leads to brown frond tips or “burned” roots.
Dividing and repotting
Every few years your fern is likely to outgrow its pot. When the rhizomes are pushing out against the side of the container or the plant seems to dry out very quickly, consider it a signal that it’s time to divide and repot.
To divide a blue star fern, carefully remove the plant from the pot. Use a clean, sharp kitchen knife or small folding plant saw to cut the plant into two or more pieces, making sure each division contains a portion of the root system attached to a portion of the shoot system. You will have to cut through the rhizomes, but don’t worry – you won’t hurt them in any lasting way. Some gardeners prefer to crack the root ball apart with their hands rather than cutting.
Once the divisions are made, loosen the remaining roots with your fingers and plant them into their own pots, using the soil mix recommended above. Maintain the same planting depth they had in their previous container. Water your blue star fern in well and don’t fertilize for the first two months after transplanting. The plant will be forming tender new roots that could be sensitive to fertilizer salts.
A close cousin worth growing
If you can’t find the blue star fern on the market, consider the blue rabbit’s foot fern as an alternative (Phlebodium pseudoaureum). The two look strikingly similar, and they are often confused for each other. Like the blue star fern, this closely related species tolerates more light than many ferns. It clings to tree branches with hairy brown rhizomes which are fun to see popping out of the top of the container when the plant is ready for repotting.
Success with growing blue star ferns isn’t complicated, as long as you keep these tips in mind. In this houseplant lover’s opinion, it’s one of the finest ferns you can grow indoors.
If you’d like to learn about more unique houseplants that are a joy to grow and collect, horticulturist Leslie Halleck’s new book Tiny Plants is the perfect place to discover them. It’s filled with itty-bitty houseplants that are adorable and ideal for houseplant lovers who have limited space.
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