Our pumpkins have always been 2/3 volunteer plus a couple planted - just in our clay soil without much attention. They mostly thrive. This year my kiddo and wife wanted to grow giants for the pumpkin contest so i built a planter box with 1/2 garden soil and 1/2 compost. We started them in a hoop house and they grew like crazy. Since hardening and removing the hoop house they have totally failed to thrive. The giants in particular have yellow vine and yellowing leaves. Pumpkins sometimes set, get fist size and then yellow. My first thought was water problem, we cery carefully monitor to keep soil damp but not flooded. Couple times i thought it was over watering and let things get a little more dry. Im at a loss other than over fertilized? Wrong nutrients? I truly dont think we have the watering wrong, what else might i do differently?
If you planted the seeds in ground, it has good survival rate. Not sure if you get any issues with soil and water…