Add the honey, cardamom and rose water and blend for a few seconds. Taste and add more sugar if needed.
Pour into glasses, top with fresh (or dried) rose petals and serve immediately.
Notes
Make sure you don't end up blending the lassi too much. Just a few seconds should be fine. Over blending it will cause it to split, and you'll be left with a grainy lassi instead of a thick and creamy one.
If you don't have cold yogurt, add a couple of ice cubes into the blender jar to get the perfect chilled lassi. Don't add the milk though- or the lassi will end up too thin.
Want the lassi to have some extra creaminess? Add a spoonful or two of heavy cream into it while blending.
To make a thicker lassi, transfer the yogurt to a cheesecloth and let it sit for a while to remove the excess liquid. You'll be left with a super thick yogurt aka hung curd, which is great for this lassi and even for raitas like boondi raita and mix veg raita.