What do cabbages need to thrive?

I've tried to grow cabbages several times. It doesn't want to head, or even make leaves, really, for me. I'm asking y'all what soil/environmental conditions they need. Do they like full sun? Do they need very moist soil? Nitrogen rich/poor? Is weed pressure highly detrimental? What needs to be done for these plants to grow well?

For head cabbage, moist firm soil slightly alkaline for preference with plenty of boron and little to no competition.

Cabbage is in the brassica family of plants along with broccoli among others. They are cool season plants and tend to perform poorly in hot weather. Cabbages tend to grow best in rich soil with a pH of about 6.5 - 7 and will usually grow poorly in acidic soils. They are considered by some to be heavy feeders and will appreciate a rich soil amended with compost, compost teas, manure from grazing ruminants or composted chicken manure as examples. I've always planted my cabbage in full sun but they do need at least a half day of full sun. A few years back I was at a friends place and observed beautiful mature heads of cabbage growing in June, here in the hot south, and I realized two things going on. They had afternoon shade so they didn't get totally cooked, and it dawned on me that if the soil can be kept cool, it will greatly help allowing the cabbage to continue to grow even approaching the summer solstice in hot weather. A simple mulch of hay or wood chips greatly helps keep the soil cool from the hot sun. Also, something else to consider is the variety and if possible sourcing seed of an heirloom variety that has been grown in a similar climate for decades. I live in Tennessee and I now look for heirloom seed varieties that comes from the southern region here, and I would recommend to others that live in more northerly climates to seek heirlooms from northern regions. It seems to me the climate adaptability is in the genes of old heirlooms grown in their respective regions. Hope this helps.

James Freyr wrote: Hope this helps.

Yes, this was helpful to me. We grew decent sized heads of cabbage this year but they now look pathetic, partly due to slug assaults and partly due to insufficient water. They actually look as though they burst, and we're told that inconsistent watering plus heat could be the culprit.
We have/had them growing amidst a lush bed of white clover, so the ground is not exposed, but it has been a very hot, dry summer here.

Thanks, James. That’s what I was looking for. I look forward to applying your advice.