Parsnips can be grown in a wide variety of situations, from open ground to raised beds to containers. The main thing to bear in mind is that they will need a clear 'root run' - if the root encounters stones or compacted earth on the way down, it is likely to fork or twist. If you have stony soil, a good way round the problem is to make a hole using a pole or bar and fill with sand, compost or a mixture of both, sowing the seed on top. Alternatively, deep containers may be utilised, again filled with a sand/compost mixture.
Parsnips, like other root vegetables will do best in a sunny location.