Giant Red
Celery in the UK

Celery seeds are tiny, you know, and they need a bit of warmth to get going. Sow them indoors in March or April, just sprinkle them on top of some moist seed compost and lightly cover with a dusting of vermiculite or a fine layer of compost. Pop them in a propagator or on a warm windowsill, somewhere around 15-20°C is grand. They can take a while to germinate, so be patient, like I say, it's not the easiest. You'll want to aim for individual seedlings, ready for pricking out when they're big enough to handle.

Once your seedlings have their first proper leaves, carefully prick them out into individual small pots. Keep them sheltered and warm for a bit, then start hardening them off gradually in late April or May, getting them used to the outside. Don't rush it, especially up here in the North East, wait until all danger of frost is well past, usually mid to late May. Plant them out in May or June, giving them about 25-30 cm between each plant, and 30-45 cm between rows. If you're buying plug plants, same rules apply for planting out.