Fertizer is crafted in Virtual Villagers Origins 2 but before you are able to craft you will have to complete Puzzle #3: Crafting the Hut
. Check out our How to Make Fertilizer guide to find out what you need to do once you have built the Crafting Hut.
In Virtual Villagers Origins 2 Chapter 1 the fifth puzzle is The Garden and one of the requirements to complete the puzzle is to make Fertilizer. To do this you need to craft Mixed Herbs and Earth. Mixed Herbs is created by crafting Grass and Wheat Grass. The process takes 4 hours (240 minutes) and once complete send an adult to the Crafting Hut to get the Fertilizer which will be one per seed.
Check out our Virtual Villagers Origins 2 Chapter 1 Puzzle #6: The Garden
guide which requires the use of Fertilizer as part of the solution.