I don't think I'll be much use to you, but maybe you'll do better.
I grew celery for the first time this year, from small plants bought at a local plant fair. It didn't do very well - got woody quite quickly.
I know you should blanch celery (cover it to stop it going green) but as this was a red variety I didn't know whether to or not - with hindsight I probably should have. I grew it in a raised bed with other salad stuff, which all grew OK.
Maggie
Never doubt that you can change history. You already have. Marge Piercy
Life shrinks or expands in proportion to one's courage. Anais Nin
I bought some purple celery seed last year, they were only tiny so I asked the supplier (realseed) what went wrong, they told me I needed to start them in Feb in a really warm place like onto of the hot water tank. I think they said they also like more manure than most roots and plenty of water.
I'm going to have another go this year, last years crop made good herbs for stews though!
Just a tip, I tried growing celery from seed in the past with various successes and failures until I spotted that celery needs light to germinate.
Since then I have had 100% germination. When you sow them, either don't cover the seed with compost or cover with perlite instead and cover the pot with clingfilm or put in a clear polythene bag.
One other problem with celery is that slugs adore them and take up residence between the sticks.
Tony
Disclaimer: I almost certainly haven't a clue what I'm talking about.