What is Silo in Stardew Valley, and how do you use it? To put it simple it is a tall farm building used to store things. In Stardew Valley you will be storing hay there.
Silo is relatively cheap farm building, you can get Robin build it for you only for 100 g. Of course, it also requires some materials, but they are not in outstanding numbers: Stone - 100, Clay - 10, Copper Bar - 5.
It is best to build a Silo before building any other farm building, or acquiring animals. Any farm animals that you will keep either in a coop or in a barn will require feeding. They are perfectly capable of feeding themselves on fair weather days, just let them out and keep some grass growing in your yard. However, on rainy days or in winter your animals won’t go outside. You will have to feed them by placing hay on the feeding bench.
You can buy hay from Marnie, but she charges 50 g per unit, and that is a robbery! However, if you own a Silo all you have to do is to prepare for rainy days by cutting some grass with your scythe, doing this will automatically add hay to your silo building Make sure you cut grass with your scythe because cutting it with anything else won’t result in hay pieces.
You can check how many pieces of hay you’ve collected by interacting with a Silo. You can also have more than one Silo, which is recommendable if you plan on having more than 8 animals to feed through the winter. In this case the capacity of all your Silo building will add up into one.