The Snow Grass is an ingredient for the "Ice Key" which opens the castle of Rem Boreas
To obtain this item follow the instructions:
- First you must get the Iceberg Tip. If you already have it that means you can enter the Ice Cavern at the North West of Rem Boreas
- Go through all places in the Ice Cavern, feel free to grab everything, you will need the Mother's and Child's tears from there. Once you finish the map, there is a stair on the 2F of the cavern that leads you to the Platinum Hill
- Once there you have to fight Muffy, only this time there will be two of them.
- Muffy will drop the Snow Grass and a teleportation red circle will appear to get you to the entrance of the cavern.