Brassicas can be planted in seed trays or directly sown into their final growing position. According to Wikipedia, brassicas ...

Most brassicas are relatively easy to grow; however, unless you're an experienced gardener, cauliflowers are best avoided. For a first time grower, try a variety of cabbage, Brussels sprouts or kale.

BUT, since manure tends to increase the acidity of the soil, and brassicas will not thrive in acid soil, this does cause a ...