1. Frosty Ferns aren't Ferns
But they are related to ferns, at least. Frosty ferns are actually spikemosses in the Selaginella genus; a variegated form of Selaginella kraussiana to be precise. I had the luxury of seeing these in production at Central Florida Ferns while writing my book Plant by Numbers, but before they were even released to the general public. Check out my Six Shades of Selaginella post for the scoop on some other pettable varieties.
2. Frosty Ferns need Moist Soil
The number one way to kill a houseplant is by overwatering, but frosty ferns and other spikemosses are the exceptions to the rule and you'll probably need to water thoroughly every 2-3 days. If the soil is starting to feel a little dry, it's time to water. If the whole plant feels lighter than usual, it's also probably time to water. If your plant starts to wilt, water immediately. Do it now. Go, go, go!
3. Frosty Ferns need Drainage
In other words, get it out of that gawdawful red cellophane wrapper so that water won't sit and rot the roots of the plant. Instead, place the pot on a saucer or use a decorative pot instead, dumping any excess water that puddles up. This doesn't mean you should let the soil dry out, though, because they like it nice and moist. Selaginella can tolerate soggy soil outdoors, but not indoors - especially since hard minerals can accumulate in the soil. Which leads me to my next point.
4. Frosty Ferns Hate Hard Water
If you frequently see hard water spots on your dishes, you have hard water. This means that your tap water carries a hidden slurry of minerals that, while harmless to us, are damaging to sensitive ferns and clubmosses. You can either use water in jugs (pricy) or filtered water, or rinse out your potting mix periodically so that the minerals don't form a yucky crust on the surface.
5. Frosty Ferns like Bright, Indirect Light
In other words, they like it bright, but shaded from the sun. Bright Indirect Light is the kind of light that most houseplants crave; bright enough to comfortably read a book, but not so bright that it hurts your eyes. If you look out the window from the plant's POV at the sunniest time of day, you should not see the sun itself. Sunburned Selaginella plants get white and parched wherever the direct sun hits - kind of like the white variegation already on the plant, but worse.
6. Frosty Ferns need Humidity
Houses are dry places, especially during winter. These humidity-loving plants can quickly turn crispy and brown in a heated home, but you can combat dry air in a number of ways. Spray the plant a few times a day with water, using a mister from the cosmetics aisle. This is great boredom buster if the plant is on your office desk. Growing it on a water-filled tray of pebbles is another option, but it works better in the company of other plants. The easiest and most attractive option is to grow it under glass using a cloche or a wardian case to keep moisture in place.
Frosty Ferns are Worth the Trouble
They sound finicky, but spikemosses are really easy when you understand their requirements: Moist soil, humidity, drainage and soft water. Few houseplants offer the tactile appeal of Selaginella, and its soft, fluffy texture on your office desk is enough to soothe your nerves until the clock strikes five.
If you don't want to commit to caring for a houseplant, don't toss it in the trash! As long as you live in USDA climate zones 6-10, frosty fern and other Selaginella kraussiana cultivars will happily occupy a moist and shady spot in your garden.