When to Plant Parsnips
Planting Window
- Direct sow
- Around last frost, once soil can be worked
| USDA Zone | Typical Window |
|---|---|
| Zone 5 and colder | April; often left in the ground over winter |
| Zone 6-7 | Late March through April |
| Zone 8 and south | Fall sowing for cooler-month maturity |
Parsnips are direct-sown like carrots and share a similar taproot structure, but they're a genuinely slower crop - 100 to 120 days to maturity against carrots' 60 to 80 - and the standard advice is almost the opposite of most vegetables: leave them in the ground deliberately through cold weather rather than rushing to harvest before frost.
Direct Sowing, Early and Patiently
Sow parsnip seed directly right around your last frost date, as soon as soil can be worked - similar timing to carrots, but parsnip seed germinates even more slowly and less reliably, often taking three weeks and benefiting from consistently damp soil the entire time, with old or improperly stored seed prone to poor germination in a way carrot seed generally isn't.
Handle Foliage Carefully
Parsnip foliage and sap contain compounds that, combined with sunlight exposure on skin, can cause a genuine skin reaction (phytophotodermatitis) - redness, burning, or blistering similar to a bad sunburn. Wearing gloves and long sleeves when handling a lot of parsnip foliage, especially on a sunny day, is a real practical precaution worth knowing about, not an exaggerated warning.
Frost Improves Parsnips More Than It Improves Carrots
Parsnips undergo the same starch-to-sugar conversion carrots do in cold weather, but the effect is generally considered even more pronounced - many experienced gardeners deliberately leave a mature parsnip crop in the ground through the first hard frosts of the season, sometimes into early winter under a layer of mulch, specifically to maximize sweetness before harvesting, rather than pulling the crop at first frost the way most root vegetables are handled.
Fresh Seed Matters More Than for Most Vegetables
Parsnip seed loses viability faster in storage than most garden seed, often dropping substantially in germination rate after just a year - buying fresh seed each season, rather than using leftover seed from a prior year the way many gardeners do with other crops, meaningfully improves the odds of a good stand.
Late-Winter-Dug Roots Are Often the Sweetest
Parsnip roots left in the ground over winter and not dug until very early spring, just as the ground thaws, are considered by many gardeners the sweetest of all, though they need to be harvested before new top growth resumes drawing sugar back out of the root.
Zone boundaries follow the USDA Plant Hardiness Zone Map (2023 revision); frost windows reflect NOAA/NCEI climate normals. Both are typical historical ranges, reviewed annually - not a forecast or a guarantee for any single year. See Methodology & Sources.
Frequently Asked Questions
Is there any downside to leaving parsnips in the ground all winter, besides just the eventual work of digging them out of hard soil?
The main practical risk is rodents, not the cold - voles and similar burrowing pests can tunnel in and feed on roots left in the ground over winter, especially under a mulch layer that also happens to give them cover. It's worth checking on an overwintered bed occasionally rather than assuming the roots are simply safe underground until you're ready to dig them.
Why didn't my parsnip seed come up well even though I planted it correctly?
Old seed is the most common culprit - parsnip seed loses viability unusually quickly in storage, so seed left over from a previous season often germinates poorly even when planting technique and timing were both correct. Buying fresh seed each year is the standard fix.
Do carrots cause the same skin reaction, since they're such close relatives of parsnips?
Not to any meaningful degree - despite being close relatives in the same plant family, carrots contain far lower levels of the sap compounds responsible for the reaction, so carrot foliage doesn't carry anywhere near the same practical risk parsnip foliage does. The reaction shows up mainly in parsnip, its wild relative, and a handful of other plants in that same family, not across the family as a whole.