Photos attached.All; the hedge faces the same way , in same soil
16 November 2020 11:08 AM
If you've been fertilising them regularly, it's likely that the soil pH in this area is incorrect - Gardenias are acid-loving plants so do best in soils with pH = 5.5 - 6.5. See more here:
https://www.yates.com.au/plants/problem-solver/other/the-importance-of-soil-ph/
Once the pH has been checked and corrected, fertilise well with a flowering plant food such as Thrive Roses & Flowers pellets: