BTW, a heads up. If you are using only ecoearth for substrate that pothos probably won't last in there. Ecoearth does not have nutrients that are easily accessible by plants. It makes a great amendment to substrates that can grow plants to help them retain moisture but that's about it in that respect. The fern might fare a bit better if it's a type that can grow epiphytically but even it will enjoy a nutrient rich substrate as well.