Thanks for the response! I planned on using the a 9V battery along with the Adafruit Feather M0 board that includes WiFi; however, I've also considered a larger board (5V output), and possibly a 12V battery. I'll be running other sensors from this board.
I think based on your feedback the following motor controller would work with the 9V battery-
I looked at the technical sheet and it does use MOSFET drivers (http://www.ti.com/lit/ds/symlink/drv8871.pdf)
My biggest concern with the latching solenoids is that if the valve does not shut off, it will stay open indefinitely. I actually tested this with my Rainbird irrigation timer (I removed the batteries while it was running). I guess that's a tradeoff. Possible nasty water leak vs. power consumption.
I plan on creating a 4x4 garden bed with drip irrigation that would likely run no more than 1 hour a day. I assumed the capacitor would help under load to ensure there's enough power for the pulse, but I'm learning this stuff as I go along.
I've looked at the OSBee implementation, and it's an excellent place to start; however, the cost is a little high, and I don't think I need all of the features as long as I'm geared for a specific valve/battery.