Planting longer cuttings is like planting instant trees. Within a month after they start growing you will have branches and leaves.
I started selling these long cuttings about 4 years ago, and some of my customers had problems in April when the trees started to grow. They died within 2 weeks. The reason for that is clear. You have to prepare the holes for these cuttings in advance and there is only one way to do it correctly: Get a small hole post digger, and dig holes at least 20" deep. (plant cuttings at least 6 ft. apart). The material removed is going to be most likely clay. Replace that clay with good potting soil and tamp it. You can do this in advance.
Now for the cuttings: scratch the lower 8" of the cuttings with a dull knife so it shows green. If you see white, then you are scratching too deep. Cut off about 1/4" off the bottom and dust the entire scratched area with hormodin. Don't forget the bottom. Now, put the cutting in the hole and push it in about 12". Add a bamboo cane parallel to the cutting and tape it so the cutting will not sway with the wind. Tamp the soil firm and mulch the area. Now you can water it generously once.
It is your choice to leave them long (if you have a long truck) or cut them down to 10 ft. or so. Cuttings are available any time after the second week in November. after adding the soil to the holes put something on top so they do not freeze before you have a chance to add the cuttings.
There is no need to do anything with these trees, they will grow -+10 ft. per year their total height will be 100 ft. in about 10 years and the trunk will be about 12 inches in diameter at the base. These trees have a life span of close to 40 years.
Someone sent me this link, whatever you can do with willows, you can do with poplars. I, also have many willows that will lend themselves
to these practices