Time-lapse effects

To answer your question about lighting in a time laps shot; it takes work. You have to have the plant indoors under a lighting setup that never changes. Or, if it's a particularly long time, you could do it outside and take a pic at roughly the same time every day and just pray there are either never clouds or the same exact amount of clouds each day (not possible where I live).

You need at least two shots. One with bare trees and another with trees with leaves. The shots need to be taken from the same camera position. You line them up and then just do a simple opacity transition between the two to get the leaves to show up. The top copy, the one with the leaves should have the tractor in it. Then you duplicate the top copy and animate a mask to isolate the tractor and the road. There are so many transitions like this that I'm sure that they just went back to the same location when the leaves came out and took another shot. The hardest part is lining up the images. They may have added a rough mask to show only the leaves to make the lineup easier.

Another way to do the shot would be to export a frame as a Photoshop file using the trees that don't have leaves, then use that image in Photoshop to paint or clone leaves from other images until you have a good composite. Turn off the original bottom layer so you are just left with the leaves, import the file and animate opacity.

There is no plug-in or effect that will automatically make leaves grow on the trees. It is going to require some very careful planning and at the very least, some artistic ability to paint the leaves.