Terry Pratchett, Neil Gaiman. Good omens (№ 247027)

In fact, in the entire apartment Crowley was so focused on indoor plants. They were spreading a powerful, green and lush, with bright, juicy and glossy foliage.
And all because once a week, Crowley went around the flat with a green plastic spray bottle-humidifier, and spraying the sheets and conversed with the flowers.
In the early seventies he was heard on radio bi-Bi-si about the benefits of talking to plants and decided that this is a great idea. Although the word "conversation" might not be quite right to characterize his actions.
His speeches he kept them in the fear of God.
Or rather, the fear of Crowley.
In addition to conversations every couple of months Crowley chose a flower that was growing too slowly or the leaves began to wither and turn brown, in General, one that looked a bit worse than the others, and showed it to the rest of the plants. "Say goodbye to your friend,' he told them. - Ah, young-green..."
He then left the flat with the offending plant in his hands and came back in an hour or so with an empty flower pot, which specifically put somewhere in a prominent place.
His plants were the most luxurious, green, and beautiful in all of London. And the most fearful.