There are directions on the RBG website for arrival from Toronto. Depending on where you're staying in Toronto, the distance will vary; but from the Downtown Core it's about 45 miles to the RBG. These Gardens (and Hamilton) are across the lake (SW Corner of Lake Ontario) from Toronto; and are more or less on the way to the Niagara Region, if driving from Toronto. To get to the RBG you exit off of theQEW in Burlington and take the 403 towards Hamilton, otherwise, staying on the QEW will take you on to Niagara Falls and Fort Erie.

I'm familiar with the Parks you describe in Niagara. There are all sorts of them along the Canadian Side of the Niagara River between the Falls and Niagara on the Lake (site of the Shaw Festival). The winery I've mentioned is well before this. If you continue on the QEW towards Niagara Falls, the winery will be roughly half way between Hamilton and the Falls. If you do the RBG, it will take you about 40 minutes to drive from the RBG to Vineland Estates winery.

Wishing you a pleasant weekend in Toronto. John Wiernikowski Hamilton, Ontario