Polypodium formosanum 'Cristatum' ET Fern is a member of the Polypodiaceae family and is native to China and Taiwan. This unique and interesting fern is also known as the Grub Fern and Caterpillar Fern. What makes this fern so unique is the rhizome. It does resemble E.T.'s finger a bit and we can understand where it got that name. The rhizomes are hard and creep along the top of the soil, sending out roots every few centimeter or so. This is not a fast growing fern and it will take a bit of time to get a full size plant. That can work in your favor if you're trying to keep it contained in a small pot or terrarium. It will thrive in a terrarium because it does appreciate the humidity, but remember to allow for water drainage. It can also be grown as an epiphyte, which is how is normally grows in its native environment. Polypodium formosanum is easily pruned as it ages so containing it isn't really an issue as it could reach heights of 18" or so.
E. T. Fern Care
Polypodium Formosanum 'Cristatum'
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Humidity
Normal
Lighting
Shade
Hardiness zone
9 - 11
Difficulty
Easy
How to Care for the Plant
Water
It is important to keep the root ball moist at all times. If your Boston fern is sitting in a somewhat dry area (instead of humid), mist with water frequently to keep moist.
Fertilizer
During the growing season, feed the fern with liquid or slow-release pellets. If you're not happy with the fern's progress, it won't hurt to slightly increase the fertilizer within reasonable limits.
Sunlight
The Boston fern needs bright indirect light when grown indoors (outdoors, it prefers denser shade). Some species of the Nephrolepis genus can be trained to handle almost full sun, but most species, including the N. extensis 'Bostoniensis' cultivar, prefer filtered, dappled light.
Soil
Boston ferns need a loamy, rich, organic mixture as a potting soil. Make sure the drainage is good to avoid rotting the roots, which will be evident if the plant is beginning to lose leaves or appears waterlogged. It's a good idea to choose a soil that contains some organic material.
Temperature
These ferns can survive the occasional blast of cold, down to 50 degrees Fahrenheit or even slightly colder for a few hours. However, they really thrive between 60 and 75 degrees.
Popularity
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