Plant keeper, is it in your room?
If so, let her know your wishes, and just give time to think it over.
That is usually the best way to get someone you care about to come to your line of thinking about something, pressure free, and open time.
Plus if it's a hobby for you, maybe you can include her in it?
My friend started his tanks, and ended up giving his 29G to his mother, when he upgraded to his 60 Gallon.