Week four is garden week, where judges Keith Brymer Jones and Kate Malone challenge the seven remaining potters to make stunning ceramics for the great outdoors. In the throw down, the potters have just 15 minutes at the wheel to make a large, medium and small flower pot - each with a folded rim. For the spot test, the potters must hand build a dozen roses in one hour. To ratchet up the pressure, they are watched by surprise guest judge Paul Cummins MBE, the ceramic artist behind the Seas of Red poppy display at the Tower of London. And in a monumental main make, the potters have to tackle their biggest challenge so far - throwing and decorating a fully functioning water feature complete with pump. But whose pot will take the 4th plinth in the winners' gallery? And who will prove a washout and have to leave the competition?