Not recommended for growing in USA - Zone 5a regions
Best grown in deep sandy, loamy soil. Use fresh seed and soak seed overnight then, after planting, keep seeds moist until seed germinate. Similar to starting carrots, maybe cover with a wooden plank or mulch until seeds germinate. They will completely fail if the seed dries out after planting and it's not unusual to have an entire packet fail. Difficult to grow in summer as the seed dries out fast and won't germinate. Leave in the ground until after frost or at least a couple of weeks of really cold weather. The cold results in the starch in the roots being converted into sugars which give the parsnip its sweet taste. Use a spade to dig the parsnip out of the ground.
Germination rates of parsnip seed are not great so sow about 3 seeds per inch and at a depth of around half an inch. Germination may take up to 20 days. Thin seedlings down so they are about 8cm (4in) apart. If you are planting in rows then space the rows about 50cm (20in) apart.
Peel and roast with vegetables or meat. The sweetish flavour of parsnips enhances most other vegetables.
We cannot help if you are overrun by giant slugs.