I buy powered calcium located in the reptile department of many pet stores. I have never seen a squirrel refuse a nut so once a day I will wet a nut with water and place it in a zip lock baggie with the powered calcium and shake. The calcium sticks to the nut. Shake off the excess calcium because it will really stick a lot. The squirrel will then pick up the nut, lick it about 30 times while turning it around in their mouth before hiding it. I have never had any luck with anything else. Hope this helps someone. It's very very easy.