Pumpkins can certainly grow in raised beds full of fresh organic matter. Sometimes raised beds offer more favorable conditions for pumpkin plants, because the soil temperature is warmer than conditions in the ground. And yes – you can probably guess pumpkin plants generally grow better in warmer conditions.
Be warned, giant pumpkin plants can quickly overwhelm a raised bed garden. Therefore, we recommend that you train the pumpkin vines to grow over the side of the raised bed and along the garden ground.