[Christine]

Had a disaster with mine - heads appeared and ran straight to flower.  Yes they were thinned, yes the soil was composted, no brassicas had not been grown there for two years, yes they were watered as required but not overly so. Yes the soil is clay based but the area has been fairly well composted over the years from the looks of it. No there is not club root on site (roots were fine when lifted). Yes I removed the lead shoot. Yes they were netted, yes the site is sheltered but sunny. No-one on site has any ideas.

Can someone give me some tips please as daughter loves calabrese.  I'm 20 miles north of Newcastle on Tyne and followed the rules in the book.

[gobs]

Well, I assume we are talking summer broccoli, very prone to run to flower, got to harvest early while heads are tight, instead of waiting for it to grow into some enormous head.

Otherwise, a lot of things can cause plants to run to seed early, but none so important as weather with a lot of them, not much you can do about that, but successional sowing.