A mobile sieving apparatus and method for harvesting cannabis pollen and trichomes separates the flowers of a cannabis plant. A large sieve panel, a medium sieve panel, a small sieve panel, and a silk screen panel are arranged in a spaced-apart stacked arrangement inside a harvesting vehicle. The sieved panels have different sized openings to enable passage of corresponding portions of the cannabis plant. The sieve panels are arranged by graduated separation, in which the distance between panels correlates to the size of the cannabis plant components passing through the opening. A harvesting panel has a solid, flat surface, and positions below the sieve panels to catch the pollens and trichomes falling through. The panels are stacked in a harvesting vehicle, sliding onto docking rails that slidably receive the edges of panels. The harvesting vehicle is lightweight to enable manual agitation of the vehicle, and enhance mobility of the panels.