Combine the blueberries and orange juice in a small saucepan. Cook over medium heat, stirring occasionally until the blueberries are fully thawed and can easily be mashed with a potato masher. It will take 5-10 minutes.
After mashing the blueberries, stir in the chia seeds. Let the berry mixture sit for 10 minutes to give it time to thicken and cool. While it sits, work on the oatmeal.
Put the oats, yogurt, milk, lavender, and orange zest in a medium bowl. Mix well to thoroughly combine.
Put half of the oat mixture into the bottom of a wide-mouth pint canning jar.
Layer half of the blueberry mixture on top of the oats in the jar.
Add the rest of the oat mixture to the jar, followed by the rest of the blueberry mixture. You can top with additional fresh or frozen blueberries, if desired. (This is optional and not included in the nutrition information.)
Put the lid on the jar and refrigerate overnight. Enjoy your soaked oats in the morning!