Several factors can contribute to plumerias growing in a sprawling or leggy manner:

1. Insufficient Sunlight: Plumerias require full sun to thrive and develop compact, upright growth habits. If they are grown in shaded or partially shaded areas, they may stretch and become leggy as they reach for sunlight.
2. Improper Pruning: Lack of or improper pruning can lead to excessive vertical growth and a sprawling appearance in plumerias. Regular pruning helps maintain a compact shape and encourages branching and flowering.
3. Overfertilization: Excessive fertilization, especially with high-nitrogen fertilizers, can stimulate rapid vegetative growth in plumerias, resulting in tall, leggy plants with weak stems.
4. Inadequate Support: Plumerias may become sprawling if they are not adequately supported as they grow. Lack of support can cause branches to droop or bend under their own weight, resulting in a sprawling appearance.
5. Environmental Stress: Environmental factors such as temperature fluctuations, water stress, or pest infestations can stress plumerias and affect their growth patterns. Stressed plants may exhibit abnormal growth, including sprawling or leggy growth habits.
6. Genetics: Some plumeria varieties naturally have a more sprawling or spreading growth habit than others. Varieties with longer internodes or weaker stems may be more prone to growing in a sprawling manner.
7. Growing Conditions: Poor soil drainage, compacted soil, or overcrowded root systems can also impact the growth and health of plumerias, leading to sprawling or leggy growth.

To prevent plumerias from growing sprawlingly, it’s important to provide them with optimal growing conditions, including full sunlight, proper pruning and support, balanced fertilization, and attention to environmental factors. By addressing these factors, you can promote healthier, more compact growth in your plumeria plants.