It depends on the situation. The time required to steam the pumpkin is related to the size of the pumpkin and the kitchen utensils used. If the pumpkin is cut into pieces and boiled in a steamer, it usually takes about 30 minutes. If the slices are steamed in a steamer, it takes 10- 15 minutes after the water boils. It usually takes about 30 minutes to steam pumpkins in an electric cooker, 10 minutes to steam pumpkins in a microwave oven and five or six minutes to steam pumpkins in a pressure cooker.