The season for growing parsnips starts in February. I start mine off in toilet roll middles filled with compost in the greenhouse. I use toilet roll middles as the ends are open and this allows the roots to grow without being disturbed(parsnips will fail or become twisted or split if the roots are disturbed). Once the seedlings have established I transfer them (still in the toilet roll middle) to the allotment having forked the area to a depth of two forks. Then using a dibber I make a hole large enough to place the toilet roll middle into the ground and plant it to the level of the soil. The cardboard tube will rot away over time leaving the parsnip to grow.
Parsnips take a long time to develop, starting in February and not being harvested until November-the following March. Old varieties need a frost to sweeten the parsnip but there are modern cultivars that can be harvested before frosts.
If you decide to sow your parsnip seeds directly in the soil choose a calm day as the seed is very light and will blow away in the breeze. Only water parsnips when they are very young or during a dry spell as with all root vegetables the dryer the soil the deeper the root will grow to find moisture.