Slice the lemon into thin rounds: Set aside while you prepare the pot.
Fill a large pot with 4 cups of water: Place it on the stove and turn the heat to medium-high.
Add all ingredients to the pot: This includes the sliced lemon, lavender, rosemary, and any floral petals you're using.
Wait for the mixture to reach a simmer: Once it does, reduce the heat to low.
Let it simmer for a few hours: Check on it occasionally to make sure there’s still enough water in the pot. Add more as needed to keep it from drying out.