Once Plumeria seeds have germinated and seedlings have emerged, you can gradually reduce the use of the transparent lid or cover that provides a humid environment. Here’s how you can transition from using the lid to exposing the seedlings to normal air conditions:

1. Partial Ventilation: After the Plumeria seedlings have emerged and developed their first set of true leaves (distinct from the cotyledons), you can start to provide some ventilation. This can be done by partially opening the lid or creating small openings in the plastic wrap or dome. This allows the seedlings to gradually acclimate to lower humidity levels.
2. Increase Ventilation Gradually: Over the course of several days to a week, gradually increase the size of the openings or reduce the coverage of the lid. This step-by-step approach helps the seedlings adjust to lower humidity without experiencing shock.
3. Remove Lid Completely: Once the seedlings have adapted to the reduced humidity and are growing well, you can remove the transparent lid or cover entirely. At this stage, the seedlings should be able to thrive in the same environmental conditions as mature Plumeria plants.

It’s important to monitor the seedlings during this transition period. If you notice any signs of stress, such as wilting or drying out, you can temporarily increase humidity by covering them partially again until they adjust.

The goal is to provide a gradual transition from the high-humidity environment needed for germination to the lower-humidity conditions suitable for growing Plumeria seedlings. This helps prevent shock and ensures the seedlings continue to thrive as they grow.