Broad beans can be precultivated, but it is easier to sow them directly. They need only 4-5 degrees soil temperature and are one of the earliest crops to get started in spring. They are often sown in compination with potatoes.
Some varieties are hardy enough to be sown in the autumn if winter temperature stays above -12°C. The Digital Gardener can provide you with information about a wide range of different broad bean varities.