Tear leaves off kale and parsley stems. Discard stems. Cut kale leaves into large pieces.
Cut lemon in half. Squeeze 1 lemon half (about 1 tablespoon juice) into blender.
Add olive oil, garlic powder, salt and parsley. Puree until well-combined.
Add kale and sunflower seeds. Pulse in blender, stopping to stir once or twice, until mixture is well-combined. If mixture is too thick to blend, add water, 1 tablespoon at a time. The pesto will not be smooth.