Any idea what topics will be covered? Is it just one day?

It is just for that day, but they do programs regularly. I attended two classes this past winter. They are doing everything from Stone walls and hypertufa to shade gardening, pruning, irrigation, and flower arranging. You choose 4 clases from a list of 16, cost is $30 pre-registgered, $35 at the door. The info seems to be all in the link.

Here is a link that might be useful: garden day 2007