When does the best Portland Pumpkin Patch open? Celebrate 20 years of fun and memories with the Plumper Pumpkin Patch in Portland, Oregon. Opening day for the Pumpkin Patch is September 23rd. With all sorts of Pumpkin Patch fun and activities, you will want to make sure you visit the Plumper Pumpkin Patch website for a list of festive fall activities to celebrate Autumn in Portland. Read our top rated Portland Pumpkin Patch Reviews online and schedule a date to come out to the best Portland Pumpkin Patch the city has to offer and pick up a cool new custom screen printed T-shirt from Hart Mind Soul and the HMS nation.