How to pick large color palettes?

An institution I know has chosen the following colors for its theme:

It is used as a banner at bottom of web pages, and the first green is used as the main “institutional” color. I wonder: does that color palette belong to some well-know “category”, or is there any evident principle that lead to its choice? I know there are recommended ways to pick three or four colors (opposing or related hues; triads and tetrads; that sort of stuff), but this doesn't seem to be the case here. How do you pick six colors? Is there any other systematic ways to do so?

Answer

General theories like compliments, tetrads, analogous and so on are a great place to start. You can even get some interesting results when you overlap systems. In the end, however, it has to come down to instinct. You analyze how you'll use a palette and let that drive your process. The colors you referenced could be fantastic together or a total train wreck -- it's all in the implementation.

My system for any institutional palette is to identify the requirements of communicating the brand (product line, business units, communication media, audience, etc). The largest palette of core colors I've recommended was 8 (with variations therein). That was primarily to support a broad product line. In the end they all had to work together and no predefined system was going to make that happen for me.