I put Miracle gro shake n feed palm food on my windmill palms. I put way to much on them. I used the applicator cap and then read to put 1 tablespoon per palm. At first within a week they looked real good and green. I watered them every evening. Well now they are turning brown on the ends. Is this a sign of too much fertilizer or too much water? What can I do to correct this. Thanks for any advice.