While scarification can improve the germination rate of Plumeria seeds, it is not always necessary to propagate Plumeria from seeds. Plumeria seeds have a tough outer seed coat that can inhibit water absorption and germination. Scarification, which involves breaking, scratching, or lightly damaging the seed coat, helps water penetrate the seed and can speed up germination. However, there are alternative methods to propagate Plumeria from seeds without scarification:

1. Soaking: Soaking Plumeria seeds in warm water for 8-12 hours before planting can soften the seed coat and improve water absorption. This method can be effective for some seeds, especially those with thinner seed coats.
2. Natural Breakdown: Plumeria seeds have the ability to break down their own seed coat over time. Allowing the seeds to naturally age for several months can sometimes result in the seed coat softening and breaking, facilitating germination. This method requires patience.
3. Light Scarification: Instead of fully scarifying the seed coat, you can lightly scratch the seed coat with fine sandpaper or a nail file. This gentle scarification can help water penetrate without risking damage to the embryo.
4. Planting in Well-Draining Mix: Using a well-draining, sterile seed starting mix can prevent waterlogged conditions that might hinder germination. Ensure the soil is moist but not overly wet.
5. Warm Temperature: Plumeria seeds require warm temperatures (75-85°F or 24-29°C) to germinate. Using a heat mat can help maintain the ideal temperature for germination.
6. Indirect Light: Place the seed container in bright, indirect light. Avoid direct sunlight, as it can be too intense for seedlings.
7. Patience: Plumeria seeds can take several weeks to months to germinate, so be patient and continue to monitor them.

While scarification can be helpful for some Plumeria seeds, you can certainly attempt to propagate them without scarification using the methods mentioned above. Keep in mind that not all seeds may germinate, and success rates can vary, but with the right care and conditions, you can increase your chances of successful Plumeria seed germination.