A starter maintained on whole wheat or whole rye ripens faster and tastes nuttier and more sour than one kept on white flour, because the bran carries more minerals and microbes that favor lactic acid bacteria. It also needs more frequent feeding and tends to be stickier.
Feed at 1:1:1 by weight and expect a rise in three to six hours at room temperature rather than six to twelve. The culture can look greyish and unimpressive while still being active; trust the smell and a float test over the visual.
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Many bakers keep a white-flour starter and build the levain with whole wheat, which gives flavor without the demanding schedule. Either works; pick one and keep it consistent.