Thanks for all the useful information that I have received here.

I will stay away from pressure treated wood completely. I will use
metal pole anchors as the base, put regular soft wood pole on the
metal pole anchors, and use stripes of regular soft wood for the rest
of the fence. And I will paint the soft wood using red-wood color
paint from top to bottom in order to reduce the chance of having
termites getting into the soft wood too soon (I am hoping that the
fence can last at least 5 years...). The color will also match my
red-wood color deck that is just a couple feet away from the vegetable
garden.

I will make the fence 3-feet too instead of just 2-feet. And I will
construct it in a way that I can easily take the fence down.

I will see how thing goes in the coming weeks.

Thanks again.

Jay Chan