Brassica napus

Brassica napus, or Rutabega, is an herbacious biennial grown primarily as a large annual root vegetable for its edible root and greens. It is believed to be a hybrid of a turnip (Brassica rapa) and a cabbage (Brassica oleracea) and is native to Scandinavia and Russia.   The genus name Brassica is Latin for cabbage.  Compared to turnips, Rutabagas are bigger, rounder, and firmer, with a slightly bitter taste. The taproot of the plant is an almost perfectly round bulbous tuber that is purple, white, or yellow with yellow flesh. The Rutabega is cold hardy and can be grown in the early spring for summer harvest or in summer for fall harvest. Soil pH should be between 6 and 6.5.

Rutabega is typically grown for fall harvest because the tuberous roots need cool temperatures for harvest of the best crop and the roots are slow to mature. For fall harvest, sow seed about 100 days before first fall frost in rows 18 to 24 inches apart. Thin seedlings to about 6 inches apart. Harvest in fall after light frost (mulch to protect roots from low temperatures of late fall) when roots are about 3 to 5 inches in diameter. Frost typically sweetens maturing rutabagas. Rutabagas can be left in the ground until needed, but can become woody if left too long. 

Diseases, Insects, and Other Plant Problems:

Clubroot is a significant problem. It will not only destroy the crop, but the spores can remain in the soil for 20 years. Other issues include powdery mildew, alternaria, root knot, anthracnose and leaf spot. Potential insect issues include aphids, loopers, root maggots, cutworms, flea beetles, and wireworms.