We transplanted an older hydrangea from my uncle’s property, so it hasn’t been cared for in several years. It is pretty wild and all over the place! How can I care for this best? Should I trim? fertilize?

I would definitely do a hard trim all along the top of the hydrangea. Leave about a 1/3 of the plant at the base. Less foliage and stems on top will mean less water is required to help it get settled in. You really want the hydrangea to grow roots and get established this first year. An evenly balanced, slow release fertilizer is best for this first year in your garden since you aren’t focused right now on growing flowers.