If you're going to use them, you can use them year round.
Place them between the brood chambers. So if you run two deeps, put the patty in between.
You use one patty at a time, When it's gone, you put in another.
How to make: Lots of recipes on the internet, but most of them are simply:
1 part crisco to 2 parts sugar. So 1 Cup Crisco and 2 Cups Sugar. Mix it up in your wife's mixer and don't tell her. Shape them like hamburgers. You can stack them with wax paper inbetween and store in freezer. Bring to room temp before putting in hive.
You can find more info by doing a google search for "grease patty recipe" you will find some with other additives. . .essential oils etc. . .
**Special tip** wear some rubber gloves, or you will have to use really hot water to wash your hands when your done. Crisco doesn't come off with cold water.