Forget the sugary pastels — the best nursery colours are soft, warm and a touch grown-up, so the room still works when your baby's a toddler chucking books about. You want something calming for nap time but with enough warmth to feel cosy at 3am.
For a soothing pink that isn't babyish, Farrow & Ball Setting Plaster is the gold standard — a dusty, slightly clay-toned pink that reads warm and serene rather than candy. It flatters in both daylight and lamplight, which matters in a room you'll be in at all hours.
If you'd rather a green, Farrow & Ball Mizzle is a beautifully restful grey-green that calms without going gloomy, and it's gender-neutral if that matters to you. For something a shade softer and warmer, Earthborn Peach Baby or their wider muted palette is worth a look — and Earthborn is the one I'd push hardest for a nursery. It's clay-based, virtually odourless, near-zero VOC and breathable, which is exactly what you want for a baby sleeping in there.
For a safe warm neutral that grows with the room, Little Greene Slaked Lime or Farrow & Ball Pointing both give you a soft, creamy off-white that never feels clinical.
The "but what about the smell" question is the big one with nurseries. Use a low-VOC, water-based finish and decorate well before the due date — ideally a few weeks ahead so the room is fully aired and cured. Earthborn Claypaint and Little Greene's Intelligent Matt Emulsion are both low-odour and wipeable, the latter being properly scrubbable for inevitable sticky fingers.
Go for a matt or eggshell finish on walls — easy to touch up, no harsh sheen bouncing light around. And test it properly: paint a big swatch and look at it in the dark with just the night light on, because that's when you'll really be living with it.