Ask-a-Dave's-Gardener: Olive tree sapling in trouble, 5 by nick27

nick27 wrote:
A few months ago I was given a baby olive tree as a gift from my in-laws. It was in great shape for the first several weeks, but over the couple months since, it\'s slowly seemed to be on the decline—the branches are wilting a lot, and the leaves have curled up and are dry and brittle. Most leaves are a duller green, and a few have started to brown as well.
For context, I keep the tree indoors on my West-facing windowsill, so it typically gets sun in the afternoon and early evening. I\'ve tried to be very careful not to overwater, giving it a good deep watering once every 10 days or so. I live in a colder climate, and the fall weather has definitely started to roll in, but the problems started before the temperature dropped.
Please help with any suggestions you have—would hate to kill my in-law\'s gift!