I have some just now started in the house. I am planning on planting cauliflower, cabbage, broccoli and kale for a fall garden. I have never tried this. I thought I was a cabbage expert. The first few years I planted cabbage they were huge. They would have heads and hardly any damage. I really don't think I started them any earlier than I do now. The first time I planted broccoli was like a dream. They were tall and formed heads. I had bad luck with cauliflower and gave up. Last year and this year I have had bad luck with cabbage. They seem to take FOREVER to form a head and I finally just get tired of fighting the bugs and pull them up. I had a lot of broccoli last year that got tall, but did not get that much from them and wondered if it was worth the space. This year I started less broccoli and they are still out in the garden. I bought a 6 pack of cauliflower and cut worms cut 2 off even with nails next to them and the other 4 are far from doing anything. I pulled up the oldest cabbage the other day. I have some more that look so so. I have kale started in the garden from seed that are growing slow, but will be okay. The other day I started several different kinds of kale, several kinds of cabbage, green sprouting broccoli, early purple sprouting and some other kind of purple broccoli. I decided to try cauliflower again and bought Snowball self-blanching and Violetta Italia. I bought the seed from Baker Creek. I am not sure I am even going to have room in the garden to plant all this. I thought peas would be done at some point, but now I wonder.
Even shading the plants won't help with temps that high.
