Purchased 2 gardenia tress from HD in March. Live I. Central Florida. Foolishly did not test soil before transplanting. Did mix organic, rich potting soil into ground soil during transplant. Trees were transplanted approx 15 ft apart from each other, in sun lite for 6-8 hr daily, and mulched. Watered faithfully every evening just before sunset, for about 2-3 weeks, then every 2-3 evenings without rain. Both were loaded with lush, healthy, dark green leaves, and many buds. Only one actually produced 2 flowers. Slowly, leaves began yellowing, without any specific pattern, the buds began browning and dropping. I added some Epsom salt for magnesium, no change. I've backed off on watering in the last 2-3 weeks due to significant rainfall every 2-3 days. Now, one of the 2, all the leaves have turned brown, dry, yet still secured to the tree. Also new growth is seen from branches. Spoke with gardening department from HD who strongly recommended more water, more water, more water, add rusted nails into surrounding soil for added iron, apply slow release acidic fertilizer OR I can dig it back up for return. My OCD personality will not allow me to give up. I will try his recommendations but am very interested in gathering as much knowledge from experienced gardenia growers as possible. Any educated suggestions with detailed expanaitions are welcome & greatly desired. Thank you.

PS- frequently inspected for pests, NONE visible. Sprayed with neem oil just in case.