They're not pink!

Our zinnias are seldom any color but a weary, faded rose. Is it the lack of acidity in the soil? Do they mix with volunteers, which are always pink? This year is different, though. We have a handsome and gaudy stand of Bright Lights cosmos, which never do as well for us as the old fashioned magenta, pink, and white ones, intermixed with many shades of zinnia. The zinnias that have succeeded in producing dark red and red-orange flowers, among other not-pink shades, are not the very rounded button-like varieties, but they are one of the smaller ones, although we don't now remember which