Question
Hi
  I'd like to plant some evergreen trees in containers in a New York City high school garden. The trees have to be in containers because the yard is all concrete.
  Will evergreens survive the winter in containers? Will their roots freeze?
   thanks

Answer
Many evergreens do very well in containers.
If the temperatures get too cold, wrap the container with insulation, or move them to a protected area.
Because they get so large, they are often awkward to handle. Try to put some kind of cart with wheels under them, so that they can be moved easily.  Some will require maintenance, such as pruning, and regular watering.
The most common plants are Junipers, and Arbor Vida. Both of these plants are easy to grow.

bakerplanter.