How wet can soil be?

I'm planning on guerrilla farming but live in the burbs. Contrary to most people, i have no problem finding water, and the only places that aren't built up are protected wetlands. If the ground is solid, but when I dig my hand into it and it is wet can I still grow? Thought of making a 1 foot pile of dirt to raise it a bit. any other ideas?

use containers

i i have a similar setup in a low wet area. im using 2 gallon pots with soil and a large hole cut in the bottom for the tap root to go through to get to the moist ground underneath.