One of the most popular cool-weather crops, turnips are a root vegetable, related to radishes and rutabagas. These veggies are wholly edible, from the root to the leaves, and they can be grown in hardiness zones three through nine. Turnip bulb formation favors cooler soil temperatures at around 60°F, and with a short growing period, these vegetables can be planted both in early spring and late summer and thrive equally well.
Nutritionally, turnips are rich in calcium and potassium, but they also have a significant amount of sodium levels. They also have smaller amounts of magnesium, phosphate, iron, zinc, and the heart-healthy selenium.
The best soil for turnip plants should measure between 6.0 and 6.5 on the pH scale. These vegetables can tolerate moderate and even poor soil, though the turnips will be wood-like and tough if grown in these conditions. To ensure the best possible produce, select an area in your garden that has partial or full sunlight, and clean the soil of any rocks, stones, or debris. Nourish the ground with compost or organic compound fertilizer. The soil should also be well aerated and very loose to allow roots to take hold.
Turnips thrive in cooler weather, and as such, the optimum planting time is early spring or fall. Their growing cycle takes anywhere from thirty to forty-five days, allowing for multiple crops each year. For early spring planting, sow your turnip seeds about four to six weeks before the last frost. This can be done directly outside. When planting a fall harvest, sow your crop at the end of summer, about the same amount of time before the first hard frost of fall.
Plant the turnip seeds about half an inch below the soil surface, placed about four to six inches apart. After they sprout, thin the seedlings as needed. It is important to keep the turnip bed well drained and to maintain even watering throughout.
Fall crop seedlings should be shaded from the harsh summer sun; later in the fall they can be exposed to full sun as cooler weather sets in.
It is uncommon for infestations to become a problem with turnips due to their short growth period; however, they are favorite for a few insect species. Because these vegetables are planted so early in the spring, fly larvae will often burrow underground and consume the root systems of turnips as nourishment, causing rot within the plant. To avoid this, use mesh row covers over your seedlings until the days are warmer, at which point the hatching cycle will be over.
Common pests such as aphids and flea beetles can infest turnip crops as well. Ladybugs will help to control aphid populations, and beetles and other creatures can be manually removed and eliminated.
Mildew can sometimes affect turnips, though this is rare. The growth of mildew can be avoided by establishing an efficient drainage system to eliminate water build-up.
When it comes time to harvest, turnips can be handled a couple of different ways. If you want to simply harvest the greens of the turnips, you can cut the leaves just above ground level once they have reached about four to six inches in height. The leaves will continue to grow from the turnip, usually allowing for several harvests before the plant has finished producing.
For the harvest of the turnips themselves, it is better to pull the vegetable from the ground when it has reached the approximate size of a golf ball. The younger and tenderer the roots are, the better taste, texture, and consistency they will have. Once the turnip has reached the size of a tennis ball, it will likely be too woody and tough to consume.
Turnips are sometimes used raw and fresh in garden salads, but most frequently, these vegetables are cooked with others as a side dish or added to soups or stews in the late fall and winter.