I think this fresh, natural and fresh scent is better than any bottle of perfume. I think this fresh, natural scent is better than any bottle of perfume.

I think this fresh, natural and fresh scent is better than any bottle of perfume. I think this fresh, natural scent is better than any bottle of perfume.

I put 'fresh' before 'natural' -- I'm not sure if there is a grammatical rule, but to my native ear it sounds a bit better :)

ALSO POSSIBLE: I think this natural and fresh scent is better than any bottle of perfume. ALSO POSSIBLE: I think this natural and fresh scent is better than any perfume.

GALSO POSSIBLE: The scent of gardenia scents in my room ALSO POSSIBLE: The scent of gardenias in my room

The sweet and rich fragrance of gardenias fills my room, sweet and rich. The sweet and rich fragrance of gardenias fills my room.

I put the smells of gardenias towards the beginning of the sentence to be more concise.

The sweet, rich fragrance of gardenias fills my room, sweet and rich. The sweet, rich fragrance of gardenias fills my room.

The original sentence is technically correct, but adjectives added to end makes more sense in a literary context.

The sweet and rich fragrance of gardenias fills my room, sweet and rich. The sweet and rich fragrance of gardenias fills my room.

Or you could also say “the fragrance of gardenias fills my room with a sweet and rich scent” or something like that - scent might not be the best word but it’s the only one I can think of right now. You might see “sweet and rich” at the end of a sentence in some books, but personally I find it to be a little formal and used more in novels, poems or other literary works as a play on words.