prei(Winter) leek is a biennial crop. The second year of cultivation, the plant comes to seed formation. Once bolting starts, the quality of the product goes brighlyt backwards. It may therefore remain outside in the winter and can still de harvested. You can place some plants in shed or basement in crates because the ground outside sometimes in the winter is frozen too hard to harvest. Some varieties are naturally suited better for this than others.
Also carrots and salsify can overwinter on spot when coved with dry material.
Kale and sprouts may overwinter outside. Sprouts you pick from bottom to top. They taste even better when they have had some frost.
Purple hardy broccoli is sown in early summer, planted in July and given one more hilling in September. At the first soft temperatures the growth resumes.
Corn salad (Valerianella locusta) is not realy hardy but resistant to -9°C and after the frost the grow continues. With a little shelter (clock, foil..) you can get early harvest.
Winter Purslane can still be sow at the end of the summer to pick or cut (in winter) for months from.

Parsnip (Pastinaca sativa subsp. Sativa, also white root) is an umbelliferous (Apiaceae). The 20 to 40 (!) cm long cream - white root has a celery- and sweet aniseed flavor. Due to the length of the taproot deep spaded or loose soil is needed. Parsnip is usually sown in the second half of April or later. The seeds are harvested in August.

krulkoolThe root can be eaten young, but also as a winter vegetable. The roots begin to thicken from November and can easily stay in the ground until March as they are hardy.
Grub after a cold period, the taste will be even better.
Parsnip was before the introduction of the potato an important staple food.
You can eat it raw or boiled or braised, fried, as stew or fried like potato chips.
I also once made ​​wine of them, but I had to throw it away (as slime). I think that the blame lay with the creator rather than the parsnip.
(Possibly parsnip is fallen into disuse because he was sometimes confused with poisonous hemlock (Chaerophyllum temulum).)

Of large parsnip carrots best remove the hardened middle.

Also Jerusalem artichoke, salsify, winter purslane, winter leek, Hamburg parsley (Petroselinum crispum var. tuberosum) are hardy.

Winter vegetable chicory
This typical white Belgian endive, known in Dutch as witloof or witlof ("white leaf") is hardly know in the U.S. Petroselinum crispum var. tuberosum is a leafy vegetable that is grown as a root vegetable. The latter is important to know for the fertilization and crop monitoring. The cultivation of witloof consists of two stages, namely first the cultivation of the carrot on the field and then growing the tight leaf crop in pits (soil chicory) or cisterns.

Use in the field little or no nitrogen. In not fine crafted soil you get branched roots leading to difficulties in later stacking in. Excavating period: from September to December.
The chicory roots remain after lifting for a minimum of 14 days lying on the field to relax.
Put them in a fan shape on each other so that the leaves always cover the roots. If they are not covered, the roots will burn by the sun.

The foliage from a root of normal size is cut 3cm above the root collar, the cut should be flat. The thicker the root the longer the left crop part should be.

Possibly you cut off the root tip so that the roots are all equaly about 18 centimeters long. Rotten leaves are removed.
Insert a row of chicory roots in a coffin. Sprinkle some ground against it. Then the next row, etc. Until the canal or crate is full. Sprinkle a layer of soil of several centimeters over the roots and rinse with a strong jet of water so that the heads become visible again and are almost free from dirt, and soil is close between the roots.
The roots now have sufficient soil and water. Basically do not water until the end of cultivation. Leave the coffins several hours outside to drain excess water. Make sure there comes no frost and no light at the chicory (dark shed or basement, cover with leaves or soil...). Four weeks after stacking in the crops are ready to be harvested.