He continued: “But because it’s a young plant, it means that its root system is fairly small.
“So therefore it’s not able to access the moisture that might be deeper down in the soil, so I’m having to make sure it is really well-watered.
“And clematis is one of those plants that really needs water. So grey water is perfect for them.”
Last month, the UK recorded its highest temperature on record, breaking 40C for the first time in history.
Another heatwave is also on its way this weekend, with temperatures expected to hit 35C.