Robertson, the 18-year-old striker on loan from Sheffield United, blasted his 51st minute drive in off the underside of the bar, giving Wrexham keeper Michael Ingham no chance. It was his first league start and his second goal in successive league games after he went on as a substitute to score in stoppage time at Peterborough ten days before.
The goal was no more than lowly Torquay deserved, for they fought back well after falling behind to Kevin Smith's early opener.
Smith, on loan from Middlesbrough, headed his second goal in successive games after Chris Llewellyn's first shot had been parried by Torquay goalie Nathan Abbey.
With the strong wind behind them, Wrexham dominated the first half. Torquay, who had to replace injured left-winger Kevin Hill with ex-Birmingham starlet Carl Motteram after 28 minutes, were happy to reach half-time only a goal down.
Both teams made changes at half-time - Torquay sending on Chris McPhee for hamstring victim Lee Thorpe and Wrexham replacing Mark Jones, who was suffering from a virus, with Lee McEvilly.
Robertson's equaliser fired up Torquay, but as conditions worsened in the second half - squalls of driving rain joined the fierce wind - neither side could add much quality to their endeavour.
Wrexham nearly snatched victory in stoppage-time when sub Juan Ugarte, on for Smith, shaved the right-hand post with a 25-yard free-kick.
But after a stormy night which tested the physical and mental resolve of all the players, neither team deserved to lose.