Gardening Methods

Does anyone know the name of this BBC TV programme/film?

It aired once in the 90s, as I recall and was about group of people who gradually turned into trees / vines. It was nothing to do with Quatermass or Day of The Triffids. I remember it ended with a man being killed or assimilated by a large vine-type tree out in his garden.
It was, as I recall, a one-off TV-movie or TV play. Very understated and creepy. All I can really recall is a chap who gradually changed into a plant/tree. There was also a scene in which some characters were sat around a kitchen table singing “Nice work if you can get it” with someone accompanying on guitar.

it was earlier than the 90s, but could it be the Tom Baker Doctor Who ‘The Seeds of Doom’?

Ash Tree – what to look for