Root Crops

Beets, carrots, parsnips, radishes, turnips and rutabagas are all commonly known  as root crops. These vegetables offer a prolonged harvest season and, for the most part, a long storage life. They also produce a large amount of food in a small amount of space.

Lime and Fertilizing

Root crops require a soil pH between 6.0 and 6.5. Strongly acid soils should be limed according to soil test results. Lime (if needed) is most effective when mixed thoroughly into the soil in the fall.

In addition to lime, broadcast 1 ½ pounds of 10-10-10 fertilizer per 100 square  feet just prior to planting the seeds. It is also a good idea to sidedress the plants with the same amount of fertilizer when they have reached about one-third their growth. To prevent burning the roots, however, apply the fertilizer three to four inches away from plants. Natural fertilizers can be very effective when the right choice is made from the many types available.

Soil Preparation

Root crops grow best in well-drained, loose soil. Drainage is important because these crops are among the earliest planted and the latest harvested. If the soil is jeavy, that is, has a lot of clay, it is a good idea to build a raised bed 4 – 5 inches high and 12 – 24 inches wide. Raised beds will help to reduce soil compaction, permit easier digging, and will allow carrots and parsnips to attain greater length and be smoother in shape. Add sand and organic matter, such as manure, to heavy soils to improve drainage.The following steps may be used to prepare soil prior to planting in the spring:

• Apply two to three bushels of well-rotted manure or compost per 100 square feet. (If carrots are to be grown, apply the organic matter in the fall prior toplanting in the spring.)

• Apply recommended amounts of lime.

• Rototill everything into the soil.

• Broadcast recommended amounts of fertilizer just prior to planting seeds and work into the soil.

NOTE: Using organic matter or manure that is not well-composed as a fertilizer for carrots can cause the roots to become rough and branched.

Watering

Root crops will not do well in a dry seedbed. Keep the seedbed moist by sprinkling the bed with water every day until seeds have germinated. Some gardeners place a clear plastic sheet over the row after the seeds have been planted and watered in order to warm the soil and conserves moisture. The sheet should be removed as soon as seedlings emerge. This procedure is especially useful for root crops such as carrots and parsnips, which have a long germination period.

Weed Control and Pests

Shallow cultivation (1 to 2 inches deep) when weeds are small is best for effective weed control because as weeds get larger they compete with root crops for water and mineral nutrition. Once seedlings are up, a mulch material such as compost or straw can be used to suppress weeds and conserve moisture. Only mulch soil that is moist and warm.

Some major insect pests include root maggots on turnip, rutabaga and radish, leafminers on beets, and carrot rust flies on carrots and parsnips.

Storage

Root crops should not be put into storage until late fall. These crops withstand autumn frosts and are better off in the garden until nights are cold enough to permit proper storage temperatures. Dig root crops when the soil is dry and prepare them for storage by cutting the plant tops about 1/2 inch above the crown and do not wash until needed. Root crops keep best between 32 and 40oF and they require high humidity to keep from shriveling. Turnips and rutabagas give off odors and, therefore, should not be stored in a basement or home cellar. All other root crops can be stored in a home cellar if it is cool enough. All root crops can be stored in an outdoor cellar or pit. Root crops keep their crispness longer when bedded in layers of moist sand, peat, or sphagnum moss.

Individual Crops

Information about beets and carrots is detailed in separate Fact Sheets.

Parsnips: Sow parsnip seeds ½ inch deep. Since parsnips are slow to germinate (approximately two weeks), quick germinating radish seeds can be sown along with the parsnips. The radishes will mark the rows and permit earlier cultivation. Since parsnips require a long growing season, there is only one seeding that should be made as early in the spring as the ground can be worked. If the garden soil is heavy, cover the seeds with sand, vermiculite, or fine peat rather than soil. As soon as plants reach a height of 2 – 3 inches, they should be thinned to stand two to three inches apart. More than almost any other vegetable, parsnips are improved by cold or even freezing. The roots can be left in the ground until late fall or on through the winter. If left over winter, they should be covered with a mulch to prevent alternate freezing and thawing and deterioration of the root. They should also be harvested early in the spring before new growth starts.

Radishes: Sow seeds 1/3 inch deep. Radishes will germinate in four to five days. Thin seedlings shortly after emergence to avoid disturbing the root system of radish plants left in the garden. For a continuous supply, make plantings every 10 days during the early spring and again starting in August. Radishes grown during midsummer produce woody and pithy roots. Radishes can be harvested at any stage.

Turnips: Sow seeds ½ inch deep in rows 15 inches apart. After the plants become established, thin plants 3 – 5 inches apart. Plant turnips in early spring, then again in summer for a fall crop. In hot weather, the roots are often strong or bitter in flavor and become pithy when they reach maximum size. Turnips reach a good size and are ready to harvest in 60 to 80 days.

Rutabagas: Sow seeds ½ inch deep in rows 24 inches apart. Plant rutabaga seeds from mid-June until July for fall harvest. Thin seedlings to a spacing 6 – 8 inches. The roots should be allowed to reach full maturity before they are pulled, usually in late September and October, in order to be sweet and of peak quality. They do not become pithy if overmature as turnips do.

Adapted from the University of Massachusetts Cooperative Extension Service, 2001