Most trees do best when planted in the fall...that may be part of why yours is wilting. Of course the soil and watering will affect them too. I would definitely wire around the bottom until it's well established. I have tall trees in my run and a wired/roofed ceiling - we just wired around the tree by cutting the wire and loosely tacking it along the perimeter of the trunk (loosely so that we can adjust as the tree grows).