My daughter will be 12 in july, 4ft 81/2 inches, grew 1 inch in last 1 1/2 month (she is swimming 1hr daily), any tips for her weight and height gain?

Need more info. 12 is a typical age to be entering puberty. Growing 1 inches in a month is good. Typically children grow 2-4 inches a year so it sounds like she is on track. She is not yet 5 feet tall but that is determined by parental height. If she has been growing consistently on her growth curve than no worries. Most girls do the most growing before the onset of menses. Ask doctor is concerned about growth.