Hi Urban Gardener
Have you checked the pH of your soil? Cauliflower like a pH between 6-7. If it is only the acidic side, then you could add some lime and if it is really high on the alkaline side, suggest you add some sulphur.
Unfortunately, there is nothing you can do to this crop, but next time also incoporate less nitrogen and some potash which encourages flowering. Are you planting them at the right time of year? They need a cold snap to form a good head.
Would also practice crop rotation and not plant them in the same spot again for at least 4 years.
Cheers Keeen Gardener
Interested in growing vegetables, annuals, herbaceous perennials and succulents. Love historic gardens and am involved with the Friends of La Trobe's Cottage in Melbourne in the garden group.