Why is a newly planted jacaranda turning brown?

Not sure when you posted this question or if you have received any answers to it but I would also Love to know the answer as the same thing happened tp three newly planted juvenile Jacarandas I planted. The leaves have browned and look quite dry and generally the tree does not look healthy. Also on one side of the tree the small branches have actually lost all their leaves and started to fall off. This has happened to all three trees! I have been very meticulous about caring for them. Watering them regularly (in warm summer when they were planted) and giving them some Seasol once a week, but now heading into the cooler months. Thought it might have been short term thing and they would bounce back but after about 4 months they are still looking the same and maybe slightly worse. Would Love some advice on helping them recover and restore them to healthy looking trees.