Petroselinum crispum subsp. tuberosum.

The forgotten parsley — the tuberous variant of ordinary parsley, grown not for its leaves (which remain edible but secondary) but for its long white taproot, similar in appearance to a small parsnip. Botanically, it's exactly the same species as Italian parsley and Forest Green curly parsley — Petroselinum crispum — simply a variety (var. tuberosum) selected over generations in Germany and Poland for hypertrophy of the root rather than for luxuriant foliage.

The name "Hamburg" refers to the Hanseatic city of northern Germany, but the variety in fact belongs to a whole Germanic and Eastern European tradition of root parsley, present in Polish, German, Austrian, Czech and Hungarian peasant cuisines since at least the 17th century. In Polish, it's the famous pietruszka korzeniowa, an indispensable element of the great Polish soups like rosół (the traditional broth served on Sundays), bigos (sauerkraut stew) and zupa pieczarkowa (mushroom soup). In German, Wurzelpetersilie, "root parsley," holds the same essential place in winter soups and peasant stews.

A two-storey plant: dark green flat-parsley foliage (usable like any ordinary parsley for cooking) reaching 30-40 cm tall, and a cream-white taproot buried in the soil, which can measure 15 to 25 cm long by 3 to 5 cm across at full maturity.

Root flesh firm, dense, pearly white, with a unique flavour: mild, sweet like a tender carrot, with the characteristic herbaceous note of parsley that makes its originality — a cross between parsnip, celeriac and parsley that no other vegetable reproduces exactly. Cook it exactly like a parsnip: roasted in quarters in the oven with oil and thyme, cubed in soups and broths (essential in Sunday Polish rosół), simmered with other root vegetables in bigos or jarzynowa (peasant soups), puréed alone or with potato, roasted as garnish for a braised meat. The leaves, secondary, cook exactly like Italian parsley.

Grower's tip: Like all parsleys, Hamburg tuberous germinates slowly (14 to 21 days) and demands patience at the start. Direct sowing preferable (the taproot is fragile at transplanting) — early May in Québec, as soon as the soil can be worked, 1 cm deep. Soaking the seeds 4 to 6 hours in warm water significantly accelerates germination. Thin to 8-10 cm in the row after emergence to let the roots form properly. Keep the soil loose and stone-free for straight, smooth roots — any obstacle in the soil makes the root fork, as with parsnip or carrot. Harvest late in the fall, after the first October frosts — like parsnip, Hamburg parsley develops its full sweet flavour only after cold has converted its starches to sugars. Excellent root-cellar keeper, 4 to 6 months in a humid cold room (0-2 °C, 90-95 % humidity).

• Open-pollinated. Germanic and Eastern European heirloom variety. Biennial — flowering in the second year. Insect-pollinated; crosses with other Petroselinum crispum (Italian and curly parsley), so isolate for seed saving if growing several varieties.
• Height: 30 to 40 cm for the foliage. Root: 15 to 25 cm buried in the soil.
• Maturity: 90 to 110 days after sowing for the root.
• Exposure: full sun; part shade tolerated in summer.
• Loose, deep, stone-free, well-drained, neutral to slightly alkaline soil. Thin to 8-10 cm in the row.
• Direct-sow early May in Québec (seeds soaked 4-6 h). Harvest after the first fall frosts for optimal flavour. Storage 4 to 6 months in a cold humid cellar.