it probly is just too low light that makes the
flower dull. or it could be that the
plant was given a constant level of a bloom booster fertilizer while in the nursery but now that has worn off. you could try giving it a bloom booster type of fertilizer... but mostly that should help it keep the
flowers.. begonias need that boost to keep blooming. so bright bright light - not hot mid-day sun.. and a good blooming fertilizer should help out a bit. they arent winter hardy so i'd keep it inside.. unless you're in
zone 10-11..... Good luck! it's a beautiful
plant