This guide will show you how to change the season lenght on servers, but also on singleplayer.
1 Season = 30 days in singleplayer
1 Season = 365 days in Multiplayer (as days passes while no one is on the server)
However if you want to change this on a singleplayer/server, you can do the following.
(If on server, skip to step 2)
1: Open the Twitch launcher. Right click on the pack under “mods” and “My modpacks”. Then click “Open folder”.
2: Open the “config” folder.
3: Find the file called “harvestfestival.cfg” and open it. I use Sublime Text to edit config files, but you can also use Notepad++ or even just notepad.
4a: If ýou want to change server, find the line:
I:"Dedicated Server > Days per season"=365
And change 365 to whatever number you want. Then save the file, upload the file to the server, if not already done so, and start it. You need to have the server turned off, before doing this.
4b: If you want to change it in singleplayer, find the line:
I:"Integrated Server > Days per season"=30
Make sure the game/pack is closed before editing it. Now change the number 30, to what you want, and save the file. Then start the pack, and it should have changed.