Five Tips for growing root vegetables

Photo credit M.E. Bartolo, Bugwood.org

Article by, Nicole Sanchez,
Horticulture, OSU Extension Service, Klamath County

Root vegetables such as carrots, beets, and turnips are among the true vegetables- edible plant parts corresponding to vegetative, or growing parts of the plant. Botanically speaking, seeds and plant parts that contain seeds are considered fruits. Tomatoes, cucumbers, and peppers are fruits, containing seeds in a variety of arrangements. Beans and corn are actual seeds. True vegetables come from the leaves, stems, and roots of the plant. Interestingly, many true vegetables are more cold hardy and thus better suited to early season gardening than the fruits, many of which need continuously warm soil for best development.

Root vegetables are relatively easy to grow, provided the soil is loose and easy to work. Clay and compacted soils are difficult for root hairs to penetrate, slowing growth and sometimes even constricting the growth of the root. Many root vegetables thrive in sandier soil that drains well: soil with too much organic matter and moisture holding capacity can cause rot issues.

Once appropriate soil has been addressed, a few considerations for growing root vegetables can greatly increase the opportunities for success.

Transplant vs. Direct seeding. Root vegetables tend to perform better when direct seeded. Taproots like carrots and radishes often respond poorly to transplanting, resulting in mis-shapen roots or stunted growth. Growers in short- season regions like the Klamath Basin sometimes transplant early beets and turnips: using paper pots or peat pots that can be planted entire, thus without disturbing the root system, enables transplanting with reduced instances of root damage.

Competition with weeds.  The young seedling stage is critical in terms of competition for water and nutrients: young root crops don’t compete well with weeds or mulch.  As they grow larger, removing every tiny weed is not as crucial. Often, root crops start off slow before developing a leaf canopy that can shade out weed seeds to prevent weeds from sprouting. Carrots have fine, delicate leaves that don’t create much shade at all. Seedling root crops should be hand weeded, mulch can be added later as the plants mature. Some gardeners have had success with interplanting root crops with fast growing lettuce or spinach, harvesting the leafy greens entirely as the root crops grow larger.

Remove the obstacles. Forked carrots, twisted radishes, lumpy beets: these can be caused by hard soil, lumps or rocks in the soil, and even large mulch or compost chunks that have been incorporated into the soil. Before planting, make sure to remove all these obstacles to root development. Finely worked soil is especially important for root crops.

Ruthless thinning.  Seeds like carrot and radish are small, and often difficult to disperse singly. When seeds sprout too close together, neither root can develop properly. Thinning is the best way to encourage the strongest roots to develop: pull the less vigorous plants out completely. Some gardeners re-plant the thinned plants where they have more space- this approach typically yields partial success.

Consistent water. Tough skins, poor post-harvest storage quality, and bitter flavor are characteristics of root vegetables that have not had consistent water. Where rainfall is not provided, deep watering several times a week is suggested for root crops. To encourage good root development, water should be available deep into the soil profile. It can be helpful to dig around in the soil after watering to gain insight into how deeply water is actually filtering through the soil. Infrequent watering can also cause stressed plants that are more vulnerable to pest issues.

Generally, root crops are considered “light” feeders when it comes to fertilizer. Nitrogen-rich fertilizer may promote leafy top growth instead of strong root development desirable for root crops. Carrots demonstrate positive response to light fertilizer during development, but additional fertilizer after planting is often unnecessary in most other root crops.

Root crops vary in time to maturity. Radishes are considered a “quick” crop, often interplanted with slower growing plants and harvested while the other crop grows on. Some varieties of radish can reach maturity in as few as 25 days. On the other end of the spectrum are parsnips, which take from 105-125 days to mature.