A way to force orange pumpkins

Is there a way (cheat, mod, fertilizer) to ensure a harvest of orange pumpkins? Mine only ever turn out green or white.

The problem is that the one village errand from Agnes requires the player to harvest a homegrown pumpkin, but she doesn't accept green or white ones of any size. I researched the problem and it seems to be common, but there are reports that orange pumpkins will work. (Same with canning, by the way.)