The 1881 American
Household Cyclopedia advises that turnips can be grown in fields that have been
harrowed and ploughed. It recommends planting in late May or June and weeding and thinning with a
hoe throughout the summer. As a root crop, turnips grow best in cool weather; hot temperatures cause the roots to become woody and bad-tasting. They are typically planted in the spring in cold-weather climates (such as the northern US and Canada) where the growing season is only 3–4 months. As the global climate warms this can increase the growing season but can also stress turnips, recent work has shown that
agrivoltaic shielding with partially-transparent solar panels can mitigate this effect and increase yields. In temperate climates (ones with a growing season of 5–6 months), turnips may also be planted in late summer for a second fall crop. In warm-weather climates (7 or more month growing season), they are planted in the fall. The average time from planting to harvest is 55–60 days. Turnips can also be grown in
controlled-environmental agriculture using
vertical farming techniques, although larger grow cups are needed than those traditionally used for crops like lettuce. Turnips are a biennial plant, taking two years from germination to reproduction. The root spends the first year growing and storing nutrients, and the second year flowers, produces seeds, and dies. The flowers of the turnip are tall and yellow, with the seeds forming in pea-like pods. In areas with less than seven-month growing seasons, temperatures are too cold for the roots to survive the winter. To produce seeds, pulling the turnips and storing them over winter is necessary, taking care not to damage the leaves. During the spring, they may be set back in the ground to complete their lifecycle. == Nutrition ==