1. Frosty Ferns need Moist Soil
Frosty ferns and other spike mosses need to be watered thoroughly every 2-3 days. If the soil starts to feel dry, it’s time to water. If the whole plant feels lighter than usual, it’s probably also time to water. If your plant starts to wilt, water immediately. Meaning do it now!
2. Frosty Ferns need Drainage
Dump any excess water that puddles up in the saucer. Selaginella can tolerate soggy soil outdoors, but not indoors especially since hard minerals accumulate in the soil. Which leads us to the next point.
3. Frosty Ferns Hate Hard Water
If you see hard water spots on your dishes, you have hard water. This means that your tap water carries a hidden slurry of minerals that are damaging to sensitive ferns and clubmosses. You can either use water in jugs (which is pricy) or filtered water, or rinse out your potting mix periodically so that the minerals don’t form a yucky crust on the surface.
4. 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; its bright enough to comfortably read a book, but not so bright that it hurts your eyes. Sunburned Selaginella plants get white and parched wherever the direct sun hits – it’s kind of like the white variegation already on the plant, but even worse.