Growing parsnips from seed is really easy but because they have a long growing period they are subject to canker - the brown tinged discolouration of the skin.
The pair you see in the photo here are straight from our own garden and are canker free.
Effectively then, to grow parsnips successfully it is best to plant them later than most of your other seeds to avoid them being in the soil too long. They will catch up so there's no need to worry about them being planted too late.
I planted mine in very late April 2014 and as you can see from the photo they are huge and the larger one of the pair is 17 inches long.The picture below shows parsnips with serious canker blight, and of course they are inedible, but most gardeners find that their canker is only a brownish tinge which can be scraped off before cooking or freezing.
Absolutely the best way of storing parsnips is to leave them in the ground until needed. They can be dug and eaten from September onwards in most of England but they will taste better after a good hard frost as the frost alters the make up of this vegetable which makes it sweeter.
NB: Leave your parsnips in the ground until needed, and they will be safe there until next Spring. However, they will not grow after that first frost.
We recommend that you purchase hybrid seeds which have a certain amount of resistance to parsnip canker.