SUNLIGHT is the key ingredient to get plumerias to bloom. At least 6 hours daily. A good fertilizer will assist, such as any LOW nitrogen fertilizer: 10-10-20; nitrogen is the first number. No higher than15. In summer, plumerias are heavy feeders whereas in winter they are dormant for most areas. Keep well fed once or twice monthly in summer; in winter, NO WATER while they are dormant. This assumes your growing area experiences frost or freeze in winter.
