Gardenia flowers turning brown
I have a new gardenia plant, long stemmed about 3-4 feet high in a pot in partial shade; as flowers bloom the petals turn brown, but don't fall. I live in Los Angeles and don't know if I'm watering too much (watering 2-3 times per week), too little or if it's time to transplant the shrub. I noticed brown spots on some of the leaves with a yellow border. I recently bought Neem oil and sprayed the shrub to prevent further fungal issues. I've also created a pebble tray with water in the event the browning of the flower petals is due to lack of humidity. I haven't fertilized yet, though. Any ideas?
If the plant is really new, a month or two, you might think about returning it to the store. Leaf spotting, if it happens on more and more leaves, often indicates a root disease, and if the plant is newly purchased, it might have been infected when you bought it. The way to determine if you're watering correctly is to investigate the soil. Use a moisture meter, or a wooden dowel or stick of some kind that you can insert into the soil and pull up, as if testing a cake. Feel the stick, or look at the meter. The soil should always be damp, or about mid-dial on a meter. I would think that a potted plant outside in Los Angeles in the summer, if it has drainage holes, would probably need to be watered every day. Neem oil is going to be useful if your fungal issues are powdery mildew, but root issues need to be corrected by fixing basic problems with watering, soil, and/or drainage. Here are a couple of articles to help you with gardenia growing: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm