Like a trusty outdoor thermometer or reliable weathervane, the scores of cars parked along Hampton Avenue and on all the available side streets near the Bayer Garden Shop signal that spring planting season has arrived. In the winter, the same car congestion means it's time to pick up a poinsettia and a Christmas tree. But Bayer is more than impatiens and Virginia pine; the center also stocks water garden accessories and plants, fountains and statues, mulch and topsoil, tropical plants and grass. And if you're of a mind to clear out your car's trunk or grab a flat-bed truck, take a trip to the Old State Road location in Imperial and load up on the bulk merchandise they carry.