Depends on where you plant the trees and if you care for them to survive the first year. Trees need water. If you are planting them on your own property, this is a stretch.

Hosting uses so many resources, so using a "green" hosting company has become a marketing flag. Check out fatcow and hostgator who use the "green" activities that they do to position themselves as "green". You can buy energy credits from wind-farms to offset the electrical resources.