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Carrot and Parsnip Growing Problems: Troubleshooting

Carrots fresh dug1
Carrots fresh harvest
Harvest carrots when they develop their color and the tops are 1 inch in diameter or smaller. Carrots can be lifted as soon as they are a usable size.

Carrots and parsnips grow best in loose, sandy, humus-rich soil. Size does not make for more flavorful carrots and parsnips. For best flavor, lift both crops before they reach maximum size.

Carrots and parsnips can be sown thickly; later thin both from 2 to 2½ inches apart or more depending upon the variety. Young thinned carrots can be used fresh in salads.

Carrots and parsnips are in the same plant family and are attacked by the same insects and diseases. Watch for the carrot rust fly, a dark-green fly that lays eggs in the soil near carrots, parsnips, and celery; the larvae dig through the soil to the tip of the carrot and eat their way upward.

For carrot growing tips see Carrot Growing Success Tips at the bottom of this post.

Here are common carrot growing problems with cures and controls:

Seedlings fail to emerge. (1) Soil crusting: keep planting beds evenly moist until seedlings emerge; protect planting beds from heavy overhead irrigation or heavy rain which will cause soil to compact and crust. (2) High temperatures can keep seed from germinating.

Seeds rot or seedlings collapse with dark water-soaked stems as soon as they appear. Damping off is a fungus that lives in the soil, particularly where humidity is high. Do not plant in cold, moist soil. Make sure soil is well drained. Avoid overcrowding carrots and parsnips.

Carrots emerge in clumps or not at all. Seed sown too shallow. Warm weather or dry conditions will cause seed to dry and not germinate. Cover seed with 1 inch of fine aged-compost or vermiculite. Keep soil evenly moist to allow for germination.

Plants bolt–flower and set seed. Exposure to below freezing temperatures or prolonged exposure to temperatures below 65°F early in the season. Protect young plants from cold with floating row cover or hot kaps.

Leaves curl under, become deformed, and yellowish. Aphids are tiny, oval, and yellowish to greenish pear-shaped insects that colonize on the undersides of leaves. They leave behind sticky excrement called honeydew which can turn into a black sooty mold. Blast them away with water from a hose. Use insecticidal soap.

Small holes in leaves of seedlings. Flea beetles are tiny bronze or black beetles that eat small holes in the leaves of seedlings and small transplants. The larvae feed on roots of germinating plants. Spread diatomaceous earth around seedling. Cultivate often to disrupt life cycle. Keep garden clean.

Leaves are chewed. Snails and slugs feed on leaves. Hand pick at night when these pests feed or set out saucers of beer at soil level to attract and drown slugs and snails.

Leaves turn yellow and then brown from the bottom up; plant loses vigor. Root knot nematode is a microscopic eelworm that attacks feeder roots. Rotate crops. Remove old plant debris from garden. If pest nematodes are persistent, solarize the planting bed.

Leaves appear scorched, yellowed, curled, and wilted. Leafhoppers are green, brown, or yellow bugs to ⅓-inch long with wedge-shaped wings. They jump sideways and suck the juices from plants. Use insecticidal soap. Cover plants with floating row covers to exclude leafhoppers.

Inner leaves yellowed; outer leaves reddish-purple; roots stunted and bitter. Aster yellows is a mycoplasma disease spread by leafhoppers. Remove infected plants. Control leafhoppers. Keep the garden free of weeds which can harbor disease.

Mottled light and dark green pattern on leaves; leaves are distorted and may become brittle and easily broken; plants are stunted. Mosaic virus has no cure; it is spread from plant to plant by aphids and leafhoppers. There is no cure for the virus. Remove diseased plants. Remove broadleaf weeds that serve as virus reservoir. Infected plants can produce edible fruit but the size and yield is reduced.

Round white powdery spots and coating on leaves. Powdery mildew is a fungal disease. Fungal spores germinate on dry leaf surfaces when the humidity is high; spores do not germinate on wet leaves. Common in late summer or fall but does not result in loss of plant. Avoid water stress. Pick off infected leaves.

Grayish-white mold growth on soil surface and clinging to roots. Southern blight or white mold is a fungal disease that favors wet conditions. Keep planting beds well-drained; add aged compost. Avoid overhead watering. Keep garden clean of debris and weeds which can shelter fungus spores.

Brown spots on leaves or roots. Leaf blight is a fungal disease–Cercospora leaf spot–spread by heavy rainfall and warm temperatures. Keep weeds down in the garden area; they can shelter fungal spores. Avoid overhead watering. Avoid planting in infested soil. Nitrogen fertilizer may help. Keep weeds out of garden.

Root tops are green. Roots tops exposed to sunlight; green chlorophyll develops. Cover exposed root shoulders with soil or mulch. Green roots are inedible.

Roots are long, thin, and spindly, or short and stumpy. Soil temperature is too high or too low. The optimal carrot growing soil temperature is between 60°F and 70°F. Roots that develop in warm soils, between 70°F and 80°F produce short, stumpy roots.

Roots are thin and spindly. Weed competition for water and nutrients. Keep garden free of weeds. Keeping the garden weed free must begin at sowing time when growing carrots.

Longitudinal cracks in roots. Soil water is inconsistent, wet then dry, wet then dry. Keep planting bed evenly moist. Mulch to retain even soil moisture. Harvest carrots before they become over-mature; carrots are best before they reach full maturity. Possible born deficiency. Test soil and apply borax to bring boron level up if necessary. Carrots with cracked roots can still be eaten.

Roots rot or have enlarged white “eyes’. Overwatering; water less often. Plant in well-drained soil. Avoid planting in heavy soil.

Roots are pale orange. Air temperatures too cool, below 65°F. Avoid planting carrots too early in spring.

Roots are hairy. Plants are over fertilized–too much nitrogen–or roots are in contact with fresh manure. Add aged compost to planting beds. Add manure to planting beds the fall before spring planting so that it has time to work into the soil. Rotate crops. Thin carrots early.

Roots twist around each, forked, or deformed. Plants are too close. Thin carrots from 1 to 2 inches apart depending upon the variety when they are young. Make sure planting bed is free of clods and rock. Growing roots will split or grow sideways if they encounter obstacles in the soil. Rough branching can also be caused by too much manure in the soil. Use only well-rotted manure.

Root forked or twisted. Root-knot nematodes are microscopic worm-like animals that live in the film of water that coat soil particles; some are pests, some are not. Root-knot nematodes feed in the roots and stunt plant growth; they are most common in sandy soils. Rotate crops. Solarize the soil with clear plastic in mid-summer.

Roots have small black holes. Wireworms are the soil-dwelling larvae of click beetles; they look like wirey-jointed worms. Check soil before planting; flood the soil if wireworms are present. Remove infested plants and surrounding soil.

Roots and stems are chewed. Carrot weevils are dark brown to coppery, hard-shelled weevils to 1/5-inch long. The larvae are white legless grubs with brown heads. The grubs mine into carrot tops and roots. Handpick and destroy. Cultivate the soil to interrupt the weevil’s life cycle. Add parasitic nematodes to the planting bed.

Roots are tunneled; rusty mush oozes from tunnels. Carrot rust fly maggot is yellow to white, about ⅓-inch long. The carrot rust fly is black and green, about 1/5-inch long. Fly lays eggs in crown of carrot plants. Sprinkle rock phosphate around base of plants. Peel off damaged area before using. Harvest carrots as soon as possible. Do not store carrots in ground through winter. Keep garden clean of weeds. Delay planting until late spring or summer to avoid carrot rust fly life cycle.

Roots are discolored and decayed. Root rot or cavity spot is a fungal disease that favors warm soil. Remove infected plants. Don’t let carrots sit in the garden; older roots are susceptible to root rot. Keep garden clean of weeds and plant debris that harbor fungus. Be sure transplants are not diseased. Rotate crops regularly. Solarize the soil in late spring or summer.

Carrots are bitter flavored. Exposure to hot, dry weather. Mulch planting beds with aged compost to retain soil moisture and keep soil cool. Carrots burn sugars in warm weather; the result is loss of sweetness. Avoid growing carrots with nighttime temperatures are greater than 60°F.

Roots are difficult to lift. Side-roots will sometimes make carrots difficult to life. Use a digging fork to loosen the soil around carrots before harvest. Use a gentle twisting motion to lift carrots. Soaking the soil with water before harvest can cause roots to rot in place.

Parsnips have poor flavor. Insufficient exposure to below freezing temperatures; parsnips develop sweetness with exposure to cold. Do not lift parsnips until the second or third frost has passed.

Carrot Growing Success Tips:

Planting. Carrots grow best in full sun, but will grow in partial shade. Plant carrots in loose, well-drained soil rich in organic matter; remove all plant debris, clods, and stones from the planting bed. Carrots will grow twisted or split in heavy clay soil or soil where obstacles impede root growth. Check the soil before planting. Carrots will not germinate and grow in crusted soil; at sowing time cover seed with light compost or sawdust or sow carrot seed with radish seed which will germinate and break the soil before carrots emerge (later remove the radishes so that they do not compete with the carrots).

Planting time. Sow carrots from early spring to midsummer. Where summers are very warm, sow carrots in late summer. Carrots grow best when the roots mature in temperatures between 60° and 70°F.

Care. Keep carrots evenly moist from the time of sowing throughout the growing season; do not let carrots dry out. Thin carrots when seedlings are 2 inches tall; thin carrots to about 1 inch apart. Two weeks later thin carrots again from 2 to 4 inches apart. Use a small scissors to thin carrots by cutting the seedlings as soil level; pulling up thinned seedlings will disturb the roots of the seedlings you intend to grow on.

Harvest. Begin the carrot harvest when the carrots are most sweet. As the variety you are growing is close to its number of days to maturity, begin tasting a carrot each day. When the flavor is sweet, begin the harvest. Continue to check your crop each day and aim to complete the harvest while the roots are most sweet. (Lift carrots late in the day for optimal sweetness.) If the crop is attacked by root maggots or other pests, lift the crop right away.

More tips: How to Grow Carrots and Planting Parsnips

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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  1. We have placed chicken wire horizontally over the top of our raised bed of carrots, to minimize rabbit damage. Now as the greens are 7-8 inches in height, the tops are above the rabbit barrier. How harmful is it to the roots to have the greens nibbled off at this height?

    • The plants’ ability to photosynthesize will be lessened with less green growth. If you are near harvest, there is no need to raise the barrier. If you are a month or more out from harvest, raise the barrier.

  2. Hi. Just wondering maybe you have the answer. This is my first year growing carrots. I dont have problem germinating my carrots seeds on the my raised bed. But once they sprout and develop 1 true leaf or two, they just stop growing. I am in zone 9a. My first attempt was on September (partiall shade) and my second attempt was on 1st week November (full sun area). Appreciate in advance for your reply. Thank you.

    • Strive to make your soil as loamy as possible; that is soil rich in humus–by adding aged compost or commercial organic planting mix. This soil will hold moisture which young carrot roots need to develop. Work your soil to a fine tilth then let it sit for a month to settle. Your September attempt may have been met with weather still quite warm which may have been too much for the seedlings. In November, days are growing shorter and growth will be naturally slowed nearly to a stop by mid-December. If you can protect the seedlings from frost and birds, they should resume growth in mid-January. Once the seedlings are up feed them a dilute solution of fish emulsion every 10 to 14 days.

  3. My Carrots, Bolero Nantes, grow in stone free, well composted soil. This year it was hot with dryness in the summer. I watered sporadically. Many of the carrots have an enlarged tip – bulbous. There are no holes or deteriorated areas. The tops did brown and whither mid-season, but grew back with cooler weather. I grow this type every year and have never seen the bulbous tips before. They are not deformed, but evenly widening out in the last 3/4″ inch into a bulbous shape. What happened?

    • The problem is environmentally related–a summer too hot and dry. Plant in late summer cool autumn harvest or in late winter or early spring for a mid- to late spring harvest. Carrots prefer cool weather.

  4. It’s my first year growing carrots in a Greenhouse. Previously I have had great results with carrots outdoors. Now though, I have a 10″ raised bed for the carrots. My soil is 30% vermiculite, 30% peat and the reaming is a mixture of 5 different commercial composts. I started them very early in the season and planted a second planting in mid August. Both plantings have been stubby i/2 inch to 2′ carrots with enormous hairy roots going sideways. I know the carrot seeds I used are ok as I have grown 8-12 in carrots from them. Their colour is good and the greens look fabulous. My beets also did a similar thing, great greens and some got as large as golf balls but otherwise, very undersized and hairy for beets. MY ckes, peppers tomatoes and celery were all really good.
    Thanks in advance for any suggestions,
    Cheers,
    Kim

    • The hairy roots are likely caused by too much nitrogen in the planting mix. The 5-composts mix is probably high in nitrogen. Carrots are also sensitive to the soil moisture level; if the soil is too dry, the roots will send out feeder roots seeking moisture.

  5. Carrots roots can become stunted and hairy for a few reasons: (1) the soil is compacted; be sure to add organic matter to 18 inches deep to keep the soil loose; (2) insufficient soil moisture; keep the soil evenly moist; (3) too much nitrogen in the soil; fertilize with a 5-10-10 organic fertilizer; (4) the plants are suffering from a disease called Aster Yellows; this disease is transmitted by insects such as leafhoppers; once infected plants will not recover; use row covers to protect plants from insects.

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