I give up, there must be an explanation so help please!

After various failed attempts at being able to grow even a vaguely acceptable cauliflower I decided to give up the challenge. However, when tidying out my seed box I found some relatively old but not ancient cauli seed so thought to hell with it I will give growing them another bash.
Sowed the seeds in a heated propagator about February. Good germination and eventually planted out the 10 strongest growing seedlings. Move on and by the middle of June the damned things were about 3 ft tall and not a sign of a head, much swearing!
My Broccolli was ready for picking ( growing next to the caulis) so went to pick the heads that were ready today. The caulis were now about 3ft 6 inches and in my way of picking the Broccolli so decided I would just rip the lot up and put them on the compost heap. Was just about to do just that and then spied what I thought was a piece of white paper in amongst a forest of leaves. Nope a cauliflower, ok not the biggest( the broccoli heads an are very big) but certainly almost acceptable. The other 9 absolutely zilch.
Please someone explain to me with the same seed, same timing, same soil, same location, nine are complete duds and a lone one is not bad, bonkers or what? Cauliflower cheese tonight yum.

 

Its a long time since I've tried cauliflower, used to get covered in caterpillars so I gave up a grew the overwintering type.

That aside, isn't there still plenty of time for them to head up, it only the beginning of July.

 

Cauliflower plants get large and forming the head can be a slow job. Depends on the variety as well. Commercially they've been bred to be ready for harvesting at the same time to reduce labour costs.
Last year I grew some after a few years gap and the best one was ready early spring after sowing in April and planting out July.
They can also suffer with boron deficiency, which affects heading up.

 

There's a special dance you have to do at midnight on the spring equinox, naked, whilst chanting the name of the individual plant, to get cauliflowers to form a head - it might be that you did it for that one plant by accident ;-)

 

I think I missed the point of the question earlier, I'm now guessing these are overwintering Caulis, I thought they were summer ones, planted a couple of months ago.

The Broccoli looks like calabrese which I always thought was tender, and grew during the summer.

 

Oh my secret is out and your drone must have been busy flying over my garden earlier in the year. There is a Scottish dance called strip the willow, some take the stripping bit literally!

 

You are correct Pete, what I call a Broccoli is indeed Calebrese, just can’t get my head round calling it by the right name.I sow it early in the year to harvest between now and the end of Septemberish. The Cauliflower were also sown in about February. I tried the over wintering variety of cauli with zero success. They obviously did not go a bomb on our winters!