Welcome to NGA, Marti. Some possibilities to consider:
Intense sunlight can cause heat stress to the plant, resulting in reduced fragrance.
Direct sunlight can accelerate evaporation of moisture and oils impacting their ability to produce fragrance. Consider smelling them early in the morning on non-windy days to see if they still retain their scent at that time.
Gardenias produce their signature fragrance from gardenol and primarily from their flowers, so any damage to the flower buds or their open blooms can affect scent production.
Gardenias may respond to overexposure to light by prioritizing other functions over scent production. Aim for only morning sun exposure if possible.
Finally, there are gardenia cultivars that produce less scent than others. While gardenias are typically known for their strong, sweet fragrance, some cultivars like Veitchii have been bred specifically for reduced scent or other characteristics. Veitchii is often noted for having milder fragrance, smaller flowers and a less intense scent compared to traditional gardenia varieties.
