Parsnips are considered a winter vegetable because they are often left in the ground after frost and near-freezing temperatures set in. The shift from warm to cool weather converts the starch in the parsnip to sugar, which gives the vegetable its unique, sweet taste. Parsnips can either be harvested within two to four weeks after cool temperatures appear, or right before spring arrives. If left in the ground over the winter, they should be dug up before new growth begins on their tops.
Clear away any loose dirt and other debris from above the parsnips. Typically, parsnips that are left in the ground throughout the winter are covered with a layer of straw to protect them from extreme weather.
Loosen the dirt above and around the parsnips with a gardening fork, being careful to avoid the actual root. Parsnips have a feathery stem that extends above the dirt, much like a carrot. That stem is a clear indicator of where the parsnip is in the soil, so try to maintain a distance of a few inches around the stem.
Dig alongside the parsnip with a garden spade, clearing all the dirt from the root. It's important to dig up parsnips as opposed to pulling them out of the ground because whole roots store much better than broken ones.
Lift the parsnip from the hole and trim back the stem to about 1 inch with a pair of scissors. Brush the dirt from the root and store it in a cool, dark place, such as a refrigerator or cellar, until use. If storing the vegetables in a refrigerator, place them in a breathable plastic bag first.