Is Ashwaghanda & Milk Safe 8 Yr Old Girl?

I'm just wondering if anyone has experience giving ashwaghanda and milk for their daughter at night? My children are heavy milk drinkers and i give this combo for my two boys at night since last year. I think it helped alot in height.. my 12 year old being 5'11 now, my 10 yr old 5'4 same height as me..

My concern is that the combo might make her start puberty early. I only want to give her maybe 1/8 tsp in 1 glass of milk. Thanks