Cauliflowers are extremely thirsty plants and they need a rich deeply cultivated soil. What more often than not leads them to producing tiny heads and going up to seed prematurely is any check on growth, like a dry spell or cold spell.
I had had very little success every growing them until this year, when I grew them in a polytunnel, enriching the soil with lots of garden compost. I watered them almost every day and they rewarded me with eleven heads out of twelve plants (one had cabbage root fly), four or five of which were extremely large. This was despite a one square foot spacing.
Now I know this works, I shall be giving my caulis intensive care. You could dry a drip irrigation system for growing them, as a steady water supply should help you grow much more successful ones.