Parsnips

I know this is a really old post, 10 years, but I've been searching out the forum and learning a lot.

I have grown Parsnips many times. I even saved the roots to produce seed the next year. I was a member of the Seed Savers Exchange at the time and offered them in the exchange. Winnowed the seed in a spare room on a tarp. Poured the seed down in front of a fan. Collected the seed that fell closest to the fan. It was heaviest and most likely viable. Dead seed and chaff landed furthest away and went to the compost.

You need fresh seed grown the previous season. It can't be last years seed. Plants that flower in spring 2018 will be producing seed for spring 2019. Plus, you have to sow very heavily as in plant 6-10 times as many seeds as you want. I would space my seeds 3" apart and plant 6-10 seeds in each spot. This way you will get at least one plant in each spot. 

You need to sow as soon as your soil is dry enough to work. It helps if you have sandy loam. Even better if you have raised beds to speed up spring time warm up of the soil. Keep the seeds moist. Be patient. It can take 3-4 weeks for germination. I have never soaked my seed before sowing. 

Don't harvest until after a few frosts.