Peel and trim parsnips. Cut parsnips into chunks that are roughly the same size.
Bring a large pot of water to boil. Add the chopped parsnips to the boiling water (either all at once or in batches, depending on the size of the pot) and blanche for 5 minutes.
Pack prepared jars with blanched parsnips. Leave 1-inch headspace.
If you want to include salt, do it at this stage. Add 1/2 tsp. per pint or 1 tsp. per quart. Cover the parsnips with the still-hot blanching liquid, making sure to maintain 1 inch of headspace.
Apply two-piece canning lids until fingertip tight.
Load jars into prepared pressure canner and process using the times/PSI listed in the notes below.
When the timer goes off, allow the canner to depressurize before carefully removing the jars.
Set the jars on a clean surface lined with a kitchen towel, leaving at least 1 inch of space between each jar. Let the jars come to room temperature (12-24 hours) and then check the seal of each lid. Any jars with unsealed lids must be reprocessed.
Label sealed jars and store in a cool, dry location away from direct light. Canned parsnips are best when enjoyed within 1 year, but are still good up to 18 months.