Mineral deficiency is one of the major causes of yellowing leaves. Gardenias most common deficiency is magnesium, nitrogen and iron. They are known for their sweet smelling white flowers, but when planted in soil that is too Alkaline they are likely to yellow. Gardenias, Camellias and Azaleas are acid loving and prefer a soil PH of 5.5-6. The soil in the New Orleans area is generally Alkaline around 6.5-7.0. To reduce PH remove mulch mix in ammonium sulphate or sulphur. We also add Ironite granules. When planting Azalea, Camellias and Gardenias we recommend incorporating peat moss to your soil to help balance PH and make it more acid. Also using crushed pine needle mulch helps to bring PH lower.
I recommend getting a soil test to really make sure what your gardens are lacking. LSU Ag center has kits available. Your plants will be really HAPPY!!
WE ARE HERE TO HELP YOU HAVE A BEAUTIFUL LANDSCAPE
Any questions call Mario
Clean Cut Landscape Co.
Your Metairie and New Orleans plant professional