I live in Houston, Texas and earlier this spring I planted a fig tree in the native soil in the ground following the instructions on the tag. I've watered, fertilized and mulched it but the leaves have been getting dry, brown, and brittle and fall off or are easily plucked off. What did I do wrong and how can I correct it? I've noticed that I have clay soil in my yard, could it be that? Also, it seems like the tree did not grow at all.