Dig parsnips after several weeks of frosty weather. Around Baltimore that means late November at the earliest, and you can keep digging through winter until new leaves push in spring. The cold sweetens them in the ground. Once lifted, a parsnip can keep four to six months, but only under conditions most kitchens can’t match, and a bowl of apples nearby can turn the whole batch bitter.
The short answer
Does a Maryland winter deliver several frosty weeks? For most of the state, yes. The mean daily minimum of the coldest month at the Baltimore reference station is 25.4°F (NOAA NCEI climate normals), so a typical midwinter night falls well below freezing. A parsnip sown in spring and left in the ground will grow, and then it will sweeten. Utah State University Extension explains that cool, frosty weather converts the starch stored in the root to sugar, and that the roots taste best after several weeks of it. The sweetening comes from nights below freezing. A comfortable hardiness zone number does not produce it.
When is the best time to lift parsnips?
Start counting at the first fall frost, which falls between October 26 and November 5 at the Baltimore station. Roots dug the week after are edible but still starchy. Give them several frosty weeks and the first good digging lands in late November or December. Until then the ground is the best storage bin you have. Digging can continue all winter whenever the soil is workable, and a thick layer of leaves or straw over the row keeps it from freezing solid. Finish before spring growth starts. Once the tops green up, the root starts spending its sugar on new leaves and turns tough.
The state is not uniform. The Eastern Shore runs milder, with fewer frosty nights, so roots there may sweeten less. Western Maryland (Garrett and Allegany counties) is mountainous and runs weeks later in spring, which shifts the sowing date but gives the cold plenty of time to work. Will Parsnips Sweeten in Maryland? goes through how much frost it takes.
How long do parsnips keep after digging?
USDA Agricultural Handbook 66 puts it at 4 to 6 months at 32 to 34°F and 98% relative humidity. That is a long keeper by any standard. It also assumes those numbers hold steady the whole time, and almost no house manages that. A refrigerator crisper comes closest. A kitchen counter is far off.
Cold is not the risk, because parsnips are not chilling sensitive. Ethylene is. A parsnip makes almost none itself, but the handbook reports that even low levels of ethylene in cold storage cause bitterness, likely from a compound called xanthotoxin. Apples, pears and any ripening fruit give off that gas. Keep parsnips in a separate drawer or container. Top them after harvest, but do not trim into the crown. The full handbook is at the USDA Agricultural Research Service.
Does the season fit?
Parsnips are sown in place, and the 100 to 120 days run from seeding. The mean last spring frost at the Baltimore station falls between April 3 and April 16, and the mean first fall frost between October 26 and November 5, which leaves a long stretch of growing weather between them. Here is how the crop fits inside it:
- Sow two to three weeks before the last frost. That means roughly mid-March to the first days of April, as soon as the soil can be worked.
- Germination is slow, and the row will look bare. Mark it so you don’t dig up empty-looking soil and sow again.
- Count 100 to 120 days from seeding. A mid-March sowing reaches that mark in late June or early July, and an early-April sowing between mid-July and the start of August.
- Let the mature roots wait. They sit in the ground through summer and into fall with months to spare before the first frost. The season fits comfortably, with a wide margin on the cold end, where the sweetening happens.
- Avoid sowing late. A sowing in early July reaches 100 to 120 days between early and late October, right at the first fall frost dates, and the roots will be small.
Western Maryland’s later spring pushes the sowing date back. Count 100 to 120 days from your own seeding and ask the county extension office for the local last-frost window. The full growing calendar is in Growing Parsnips in Maryland.
What goes wrong here
- Forked or stubby roots in heavy or stony ground. The tip hits clay or a stone and splits. Utah State University Extension recommends deep sandy soil and says heavy soil must be double dug. Loosen the bed two spades deep and pull out stones. A state soil map is a starting point. Squeeze a moist handful in your own bed, and if it holds a tight ribbon, treat it as heavy.
- Forked roots from overwatering. This is a separate cause, and it can happen in loose soil. Constantly wet ground encourages the root to branch and can rot it. Water deeply, let the surface dry between waterings, and build a raised row where water stands after rain.
- Bare soil after sowing. Seed that takes a long time to sprout often gets blamed too early. Keep the surface evenly damp, mark the row, and use fresh seed each year, since old seed sprouts poorly.
- A season that runs out. Parsnips sown in summer run into the first fall frost with small roots. Sow in the spring window, from mid-March to early April.
- A winter too mild to sweeten. On the Eastern Shore, or in a year with few freezing nights, the root grows fine but stays bland. Leave it in the ground until it has had several frosty weeks, and don’t expect much sweetness if the nights never drop below freezing.
- Bitterness in storage. Ethylene from apples or ripening fruit does it, even at the right temperature. Store parsnips apart from fruit, topped but with the crown left intact.
Common questions
Can parsnips stay in the ground all winter in Maryland?
Yes, since they are not chilling sensitive. Mulch the row so you can dig when the surface freezes, and lift everything before the tops regrow in spring. Pests that tunnel into roots are covered in What Eats Parsnip in Maryland, and When.
How long do dug parsnips last?
Four to six months at 32 to 34°F and 98% humidity held steady. A typical home refrigerator won’t match that exactly, so check the roots now and then and use the softest ones first.
Can I store parsnips next to apples?
No. Low levels of ethylene in cold storage make parsnips bitter, and apples and other ripening fruit release it. Keep them in a separate drawer or container.
How long do parsnip seeds take to sprout?
Give it time. The 100 to 120 days to harvest are counted from seeding, so the clock is already running while the row still looks empty.