Yes, you can cross-pollinate Plumeria varieties with different flower colors. Cross-pollination between Plumeria varieties with varying flower colors can lead to fascinating results in the resulting offspring. The seeds produced from such cross-pollinations may inherit traits from both parent plants, potentially producing flowers with unique color combinations or patterns. Gardeners and breeders often perform such cross-pollinations intentionally to create new cultivars with striking and unusual flower color variations. Observing and experimenting with cross-pollination can lead to exciting and beautiful outcomes in Plumeria flower color diversity.