I know that my cedar is at least 100 because my neighbor had his cut down and sold and we were offered $ for this one and told the est. age. Anyway, I'd like to know if I can plant anything underneath. I have perriwinkle(only grows to 1 side for past 3 yrs.and stays small) I planted 2 lilacs and forsythia nearby, but not growing much (3rd yr. this spring) They get sun. Is the cedar sucking everything up? Should I add something to soil? Lilacs&fors. are @5ft. away fr. tree.