When it comes to root crops, there are a few key things to consider when trying to grow for size, consistency and flavor. Unlike many other vegetables, much of the development of the crop will be hidden in the soil, so it is important to take steps to ensure that the plants have a growing space with good tilth, high organic matter, diverse nutrients and adequate drainage. You'll want to make sure that the plants have access to a balanced selection of micronutrients by taking a soil test and while you may be tempted to feed nitrogen fertilizer for optimal gains, too much nitrogen can lead to large leaves, bitter flesh and hairy roots. Root crops thrive when fed organic fertilizers that are heavier in phosphorus and potassium. Compost is an excellent soil amendment for root crops as the nitrogen load is often tied up in the humic compounds made by the microorganisms within. This makes the nitrogen available to the plants, but not soluble to the greater environment. Another issue with heavy applications of nitrogen fertilizers is the inevitable competition that root crops will have with emerging weeds.

Root crops germinate best when the soil temperature is within the window of  50°F to 60°F. Seeding root crops can be tricky, as you'll likely seed them directly into the soil in rows. Often, even with a walk behind seeder, the sowing will be dense and need to be thinned. Some growers have started to transplant root crops, such as beets and radishes, to give them a jump on weeds and to allow for precision spacing and crop planning. Root crops have a particularly difficult time competing with weeds. It is important to remove emerging weeds as soon as possible so that the act of removal does not disturb the developing roots. Hoeing weeds just as their first true leaves begin to grow is ideal timing. The overall hoeing of the very top layer of the soil around the root crop also creates a barrier between the delicate soil life that is essential in helping your plants to grow and the variable conditions of sun, wind and rain above; this technique is known as "dust mulching".

While the days to maturity can vary widely, (radishes having a very short growth period versus parsnips that need at least 100 days in the field), many root crops are excellent candidates for succession planting. Having more than one planting of these delicious crops ensures that throughout the season, a fresh harvest of nicely formed, tender roots are available. For many of your root crops, the spring succession will have the best conditions for development and your summer plantings may require a weekly irrigation schedule, depending on the weather. Later plantings may also be more susceptible to pest pressure as insect populations begin to peak, and floating row cover is a good way to allow your crops get a good start while preventing pests like flea beetles from tearing through developing leaves. Flea beetles are a difficult pest in particular, because while the adults feed on leaves, simultaneously their larvae will be feeding on the plant's roots.

Beets

Beets belong to the family Amaranthaceae along with crops like amaranth and swiss chard. They are considered a cool season crop, but can be grown throughout the growing season in more temperate locations or in growing systems that offer partial shade during the hottest months to prevent bolting. Surviving near-freezing temperatures, beets are a commonly grown fall and overwintered crop in warmer zones. Beets can be harvested at any stage and the entire plant is edible. Beets will struggle to size up when there aren't sufficient levels of boron, calcium, magnesium and potassium.

  • Start the first sowing of beets in early spring and plant again every 2-3 weeks
  • Pre-soaking seeds for 24 hours before planting can help speed up germination
  • Your last sowing of beets should be about 4-6 weeks before first fall frost
  • Beets do not grow well in soil with a low pH and the optimal range is between 6.0-7.0
  • Seeds should be sown 1/2 inch deep and thinned to 2 inches apart
  • Seeds should be watered regularly after being sown to promote even germination
Beet Pests:
  • Leaf Miners Lyriomyza spp.
  • Leafhoppers Cicadellidae spp.
  • Aphids Aphidoidea spp.
  • Cutworms Noctua spp.
  • Rove Beetles Blapstinus spp.
  • Flea Beetles Phyllotreta spp.
  • Beet Cyst Nematodes Heterodera schachtii
  • Beet Webworms Spoladea recurvalis
  • Blister BeetlesEpicauta spp.
  • Root Maggots Delia spp.
  • Spider Mites Tetranychidae spp.
Beet Diseases:
  • Bacterial Blight Pseudomonas syringae pv. aptata
  • Downy Mildew Peronospora farinosa
  • Cercospora Leaf Spot Cercospora beticola
  • Scab Streptomyces scabies
  • Fusarium Yellows Fusarium oxysporum f. sp. spinaciae
  • Damping Off Rhizoctonia solani
  • Beet Western Yellows Virus (BWYV)
  • Powdery Mildew Erysiphe betae
  • Beet Curly Top Virus (BCTV)
  • Root Knot Nematode Meloidogyne spp.

Carrots

Carrots belong to the Umbellifers family along with crops like parsley and celery. They are considered a cool season crop, but are candidates for season long succession plantings in regions that stay more temperate in the summer months. Carrots are excellent overwintering crops with protection and are relatively easy to grow, preferring loose, sandy soils. Dense or obstructed soils can lead to root deformity. Carrots can be harvested at any stage and the entire plant is edible (yes, there is such a thing as carrot top pesto.)

  • Start your first sowing of carrots in early spring and plant again every 2-3 weeks through late spring
  • Carrots require moisture to germinate and must be watered consistently after sowing to ensure germination
  • Sow carrots for fall in mid to late summer, 10 weeks before first fall frost
  • Plant carrots in full sunlight or plan successions that develop in partial shade during the hottest months
  • Sow 1/4 inch deep into the soil and thin to 3 inches apart
  • Don't lose hope, carrots are slow germinators and may take 2-3 weeks to pop up
Carrot Pests:
  • Armyworms Spodoptera spp.
  • Yellow Woollybear Spilosoma virginica
  • Parsleyworms Papilio polyxenes
  • Carrot Rust Flies Psila rosae
  • Vegetable Weevil Listroderes difficilis
  • Tarnished Plant Bug Lygus spp.
  • Root Knot Nematodes Meloidogyne spp.
  • Flea Beetles Phyllotreta spp.
  • Wireworms
    • Aeolus spp.
    • Anchastus spp.
    • Melanotus spp.
    • Limonius spp
  • Aster Leafhopper Macrosteles quadrilineatus
Carrot Diseases:
  • Black Canker Itersonilia perplexans
  • Aster Yellow Disease Phytoplasmas spread by Macrosteles quadrilineatus
  • Black Root Rot Thielaviopsis basicola
  • Leaf Blight Alternaria dauci
  • Rubbery Brown Rot Phytophthora porri
  • Bacterial Leaf Blight Xanthomonos campistris pv.carotae
  • Fusarium Dry Rot Fusarium spp.
  • Cercospora Leaf Spot Cercospora carotae
  • Sclerotinia Rot Sclerotinia sclerotiorum
  • Scab Streptomyces scabies
  • Lateral Root Dieback Pythium spp.

Radishes

Radishes belong to the family Brassicaceae along with crops such as mustard greens and bok choy. Radishes are considered a cool season crop and are excellent candidates for succession planting. In areas where summer temperatures are more temperate, radishes can be sown all season long. Radishes have a quick growth cycle and can be inter-sown into many other crops with great success. Heat stress can cause radishes to bolt. The entire radish plant is edible and can be harvested at any stage.

  • Start your first sowing of radishes in early spring and plant again every 1-2 weeks
  • Radishes are considered easy to grow and germination may occur without irrigation
  • Sow seeds 1/2 inch deep and thin to 1 inch apart
  • Harvest radishes early and often as they are prone to splitting, bolting and losing quality when left to mature too long
  • Sow radishes for fall 4-6 weeks before the first fall frost
Radish Pests:
  • Root Maggots Delia spp.
  • Flea Beetles Phyllotreta spp.
  • Cutworms Noctuidae spp.
  • Aphids Brevicoryne brassicaea
  • Wireworms
    • Aeolus spp.
    • Anchastus spp.
    • Melanotus spp.
    • Limonius spp
  • Cabbage Loopers Trichoplusia spp.
  • Harlequin Bugs Murgantia histrionica
  • Slugs Gastropoda spp.
  • Vegetable Weevil Listroderes difficilis
Radish Diseases:
  • Alternaria Leaf Spot Alternaria spp.
  • White Rust Albugo candida
  • Damping Off Rhizoctonia solani
  • Fusarium Yellows Fusarium oxysporum
  • Clubroot Plasmodiophora brassicae
  • Downy Mildew Peronospora parasitica
  • Black Root Aphanomyces raphari
  • Sclerotinia Rot Sclerotinia sclerotiorum

Turnips

Turnips belong to the family Brassicaceae along with crops such as collards and cabbage. Though they are hardy biennials, turnips are typically grown as annuals in successions. Turnips are cool season crops most commonly grown in spring, fall and winter with salad turnips, (a quick maturing, tender type of turnip), sometimes grown throughout the peak of the growing season alongside radishes. Heat stress can cause turnips to bolt. Turnips can be harvested at any stage and the entire plant is edible.

  • Sow turnips in early spring and again in late summer and fall for fall and winter harvests
  • Plants will germinate quickly and may do so without irrigation
  • Turnips do not transplant well and should be sown into the soil in a location with direct sun
  • Sow seeds 1/2 inches deep and thin to 4-6 inches apart
  • When growing turnips for turnip green harvesting, plants do not need to be thinned
Turnip Pests:
  • Flea Beetles Phyllotreta spp.
  • Root Maggots Delia spp.
  • Flea Beetles Phyllotreta spp.
  • Cutworms Noctuidae spp.
  • Wireworms
    • Aeolus spp.
    • Anchastus spp.
    • Melanotus spp.
    • Limonius spp
  • Aphids Brevicoryne brassicaea
  • Cabbage Loopers Trichoplusia spp.
  • Root Maggots Delia spp.
  • Harlequin Bugs Murgantia histrionica
  • Slugs Gastropoda spp.
  • Vegetable Weevil Listroderes difficilis
  • Cabbage Whiteflies Aleyrodes proletella
Turnip Diseases:
  • Alternaria Leaf Spot Alternaria spp.
  • Clubroot Plasmodiophora brassicae
  • Sclerotinia Rot Sclerotinia sclerotiorum
  • Cercospora Leaf Spot Cercospora brassicicola
  • Black Root Aphanomyces raphari
  • Damping Off Rhizoctonia solani
  • Turnip mosaic Virus (TuMV)
  • Black Rot Xanthomonas campestris