it should not effect growth or food spoilige to be honest but just because you have longer months it means you need to have bigger food stockpiles for like winter or when your crops stop growing and longer months in my opinion are better for like big farms cause the month is longer when you are in season the crops are in the right temperature for longer so it should grow a bit faster
so food spoilige is not realy a problem here it just means you need to have food cause in 20 days the avarage food that is not in a crock or like grains will spoil but with crops you can get like a harvest each month so the only problem is that you need like more food for each month because a month takes 20 days