When growing, one of the most common problems is the lack of heads.
If the ovaries have not formed the expected fruits, the reasons may be as follows.
Why cabbage heads don't form
The first reason is the planting material. For example, there will be no heads if the cabbage has been cross-pollinated with other cruciferous plants or is intended for growing in other climatic conditions.

Secondly, the location is wrong. Cabbage requires a bed with non-acidic soil that is exposed to sunlight all day.
By the way, for the same reason, you can’t plant cabbage in a bed where cruciferous vegetables have already grown, otherwise you will never see the heads of cabbage, since the soil is depleted.
Cabbage also needs the right temperature, not exceeding 20 degrees and not below 15 degrees Celsius, otherwise its growth slows down.
The fruits will not set without proper feeding and without regular watering. Keep in mind that the soil should be moistened to a depth of 3-40 centimeters, otherwise the plant will experience a water deficit.