Suspect its site conditions. Caulis and broccolis are gross feeders, needing space, light and cool moist conditions, deep rich soils and, looking at the colour of foliage of commercial crops , plenty of something beginning with N. According to T&M cultural instructions, they produce plants upto 16" across, 18" high. Did yours? To enable that, you would need to plant at 18" centres ,using your ground for a minimum of 6months. If planted out in May, the crop will be maturing in November, thats 2 months off yet. The challenge for next year is on! Personally prefer calabrese.
