I planted Broccoli raab seeds early this spring. They came up just fine, but they more or less bolted immediately. What happened to cause this?
Broccoli raab, Rapini, or Brassica rapa, Ruvo group, resembles turnip greens more than it does the more familiar head-forming Broccoli. It has a tendency to bolt (form flowers and go to seed) when temperatures are too low or too high. Sometimes cole crops bolt when they have been exposed to seesawing temperatures, but they may also bolt in reaction to other stresses, such as insufficient nutrients (like nitrogen), or competition from weeds. The following information from Clemson University Extension refers to Chinese vegetables, but it provides useful tips on growing cole crops, such as:
Bolting can be prevented by:
- Maintaining a steady, moderate rate of growth.
- Setting out young, healthy transplants that have not been stressed.
- Watering well when transplanting to start root growth and remove air pockets from the soil.
- Planting at the correct time for your area.
- Growing slow-bolting varieties.
Although you were probably hoping for green unopened flower buds, the flower shoots, stems and leaves are also edible. Try sowing through early fall, and provide the optimum water and soil conditions. North Carolina State University Extension (link now archived) has additional information about this plant.