Q.How to turn green pumpkins orange
How do you get green pumpkins to turn orange?
Certified GKH Gardening Expert
This article should also help: https://www.gardeningknowhow.com/edible/vegetables/pumpkin/getting-green-pumpkins-to-turn-orange-after-the-pumpkin-vine-dies.htm
You need to give them time to mature naturally. Next spring, you can get a jump on the season by planting seed 3-4 weeks before your last average frost. Use biodegradable containers, they don't like their roots disturbed. Put them in super bright light...remember you're trying to mimic the sun. Fertilize and water until planted. Try to get a variety that matures quickly. Zone 3 doesn't give you a long growing season.