We planted the tree this morning! First, the kids helped collect some rocks from our "extended" back yard. We put those in the bottom to help the soil drain. We also propped the wine barrel up on a couple bricks, so it's a couple inches above the ground (better draining).
Planted some Sequoia Strawberries around the top. We'll see how they do! The roots of the tree are going to be very deep in the barrel, and the strawberry roots are super shallow. I just need to get some sand or hay for around the bottom of the strawberries to prevent weeds.