Gardening Australia, 6.30pm, ABC Is it possible to grow a magnificent garden in a very cold climate? Well, since there are quite a few in northern Europe, I’d imagine the one we’re going to look at, halfway up that Tasmanian hill called Mt Wellington, will thrive. Top Gear, 7.35pm, SBS Billed as a high- octane mix of performance cars, adrenalin, comedy and celebrities, this show continues to set the bar other car programs must live up to. It’s hard to put a finger on exactly what it is that make this the one, but every car fanatic and motoring journalist I spoke to gave it the nod. Presenters Jeremy Clarkson, James May and Richard Hammond thrive in the atmosphere of a studio audience, egging each other on to ever greater feats of egotism and daring. In tonight’s repeat, get another look at the Porsche Cayman S; and have a second twirl in a radio- controlled car.