I grew parsnip & carrots together a couple of years back, they seem to be fine, but didn't grow very big... although I think it's a soil issue because they had very lush green huge top growth...
I successfully grew the following varieties:
- All Seasons (started from seed all year, except summer)
- Early Red
I often grew the smaller, fatter, shorter carrots - it's just easier ;)
I found out another new thing - if you pull up young carrots and they are pale in colour, it indicates that your soil is too acid. Can confirm this, carrots I pulled up from amongst a yellowing patch of parsley (which missed out on the recent liming due to maturing silverbeet plants) are indeed a very pale colour and fairly tasteless.