This Spiegel article reveals:
In the mid-1990s, few in Germany had ever heard of Halloween, and even fewer celebrated it. Now, it's a €150 million a year industry.Dieter Tschorn, a German businessman started promoting the event in 1994 and it took off.
In 2007, 4,600 tons of pumpkins were sold in Germany, says Tschorn. One can buy Halloween bread at the baker's, Halloween sausage at the butcher's, Halloween cocktails at the bar and, of course, Halloween candy in the nation's supermarkets. Tens of thousands of German children now go door-to-door, holding out their bags and saying "sweet or sour," the German version of trick-or-treat.
The Halloween promoter says that the holiday has become an industry worth around €160 million in Germany, in third place behind Christmas and Easter. In 1994, that number was close to zero.
I recently went to the The Erlebnisshof Klaistow about 50km away from Berlin where a pumpkin festival was held. You can see all the innovative sculptures people can do with pumpkins here. The best pumpkin of the region weighs 260 kilos: