The best time to plant trees is in the early spring and the fall.
I may use a lot of wood from fallen trees, but I also plant many evergreen trees from seedlings in around the Guelph, Rockwood area.
If the weather is hot and dry you must make sure you can water your trees.
Some evergreen trees like the Colorado Blue Spruce can withstand a mild drought, and once they are established, the roots will grow deep into the earth to seek water.
Fertilize your trees in the early spring to give them a boost for rapid growth and good health.
The way that I plant ball and burlap tree is to keep the wire cadge and the burlap on the tree and bury the tree up to the top of the burlap.
If you are planting your trees in a windy area, you may need to stake the tree. After a year or 2 the stakes may be removed.
Happy spring and happy planting