I have been buying trees from our Wal-Mart and a garder that has $10 trees. They are about a year old. I am putting in Aspens where we see the trees (spend most of our time) and cotton woods from where the wind comes most. We are using tree spikes and watering everyday. What else can we do to increase their growth. They are both fast growers and drought resistant. But I am okay with using any thing that will make them grow faster.