When garlic powder hardens, it is a sign that moisture has seeped into the bottle. Keeping garlic powder fresh requires more than just putting it in your pantry. Proper storage ensures that your garlic powder, in addition to all of your spices, will stay fresh longer and won't become hardened in the bottle. Preventing hardened spices is easy to do.
Pour garlic powder into a clean, dry airtight container. The container can be anything from a small bottle to a Tupperware container, but it must have a sturdy, airtight lid.
Add several grains of brown rice to the garlic powder. When added to spices, rice absorbs moisture, which prevents clumping and hardening.
Store the garlic powder in a cool, dry place away from direct sunlight and heat. To ensure maximum freshness, you can store the airtight container in the refrigerator. Refrigerated spices retain freshness longer because of the cool temperature in which they are stored.
Never add garlic powder to a container that just came out of the dishwasher; the remaining water and heat will cause the garlic powder to harden quickly.