Vartax was shielded with some sort of cosmic barrier that kept it hidden and its surface relatively dark. It had a breathable atmosphere and supported abundant grass and trees.
In the 2260s, a number of Zondrefugees invaded Vartician cities, and the Varticians fled into deep caverns. The Zonds then proceeded to use up the planet's resources.
In 2267, the USS Enterprise was passing near Vartax. The Zond made first contact and through deceit managed to maroon the starship's crew on Vartax. But Spock had remained hidden aboard the ship, and he was able to overcome the Zond leader. The Zond refugees were sent back to Vartax aboard a space bug until Starfleet reinforcements could arrive, but the Zond preferred to self destruct the shuttle and commit suicide rather than return in defeat.