Tony O’Neill, gardener and author of the popular “Composting Masterclass” and “Your First Vegetable Garden,” combines lifelong passion and expert knowledge to simplify the art of gardening. His mission? Helping you cultivate a thriving garden.
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Carrots from the store can’t compare to those fresh from your garden, but growing them can be a pain if you don’t have guidance.
Carrots (Daucus carota var. sativus) have six common pests and eight root-vegetable diseases. The good news is that you can ensure a bountiful harvest of crunchy carrots with the right precautions. Carrots are part of the large parsley family (Apiaceae) but need root crop management.
Table of Contents
About Carrots
The parsley family (Apiaceae) consists of plants with umbels, including angelica, anise, caraway, celery, celeriac, coriander/cilantro, cumin, dill fennel, lovage, parsley, and parsnip.
The carrot (Daucus carota, subspecies sativus) is a subspecies of Queen Anne’s lace (Daucus carota).
The EPA groups plant management as Group 1: Root Vegetables, and includes beet, carrot, celeriac, chervil, chicory, ginseng, horseradish, parsnip, radish, rutabaga, and turnip.
Some management strategies are family specific, and some are EPA group specific. A third grouping defines a plant’s hardness, roughly warm-season and cool-season plants, subdivided into tender, semi-tender, semi-hardy, and hardy.
5 Things to Remember When You Grow Carrots
- The carrot is a cool-season, semi-hardy vegetable that does best when soil temperatures are 80°F/27°C with seeds germinating in soil between 50 and 85°F/10 – 30°C.
- Carrot seeds are small (50,000 per pound) but not as small as tomato seeds (160,000 per pound). They are shallow-rooted (6 – 12 inches), and thinning must be done by pinching crowded seedlings off. Cultivate with care.
- Carrots need consistency. Periods of drought will cause stunted roots and ruin crops, but over-watering compromises root health. Keep the ground moist consistently.
- Carrots can manage clay soil, but root growth is poor in compacted soil. Avoid rocky soil or sandy soil that’s unable to retain moisture. Compost adds beneficial microorganisms, keeps the soil moist for longer, and provides better access to nutrients.
- Grow carrots (and other root crops) in raised beds to solve several potential problems, improving soil temperatures, improving drainage, and helping to loosen the soil. Loose soil improves carrot shape, growth speed, and tenderness and avoids growing deformed roots.
Carrot Planting Timing
Depending on the carrot varieties used and where you live, carrot planting can be either in spring, spring and fall, or throughout the year (except the hottest months).
Remember that it takes a carrot two to three months to mature. Baby carrots can be harvested earlier, but some cold is good for root quality.
Northern States
Remember that the best time to start carrot plants for a harvest in the fall or winter is in the middle to late part of summer, allowing carrots to mature for harvesting.
Gardeners in the north can extend the carrot season by mulching and using low tunnels. It should be noted that these approaches are intended to lengthen the time to harvest carrots, not for growing carrots.
I recommend you choose a cold-resistant (Parisian heirloom) grown under mulch.
Carrot roots, when fully developed, are frost resistant and can be picked even after they have been exposed to some frost.
Upper South States
Late August and into September are the best times for gardeners in the Carolinas to Georgia, southern Arkansas, Sacramento, California, and similar climates to plant carrot seeds. The last day for planting carrots is typically in late September.
The relatively colder winter temperatures will produce a particularly sweet late-fall harvest despite the challenges.
Deep South States
Gardeners in Florida, South Texas, Southern California and similar climates will find that carrots continue to grow vigorously and happily throughout the winter.
You can sow seeds in several successions throughout the fall and winter months. It is best to harvest carrots during the coolest part of winter when the roots will have the most flavorful sweetness.
Temperature Considerations When Sowing Carrot Seeds in the South
Often, the easiest way to keep carrot roots is to leave them in the ground and pick them up as needed.
This is fine for cold and moderate weather, but if your weather is warming up and you expect very hot days, pull those mature carrots for storage in the root cellar or other cool, dark, dry spot.
Hot weather will make the roots bitter or cause the plants to bolt.
Consider putting a shade cloth in warmer regions to cover the carrot bed until the plants become established. You want to avoid the full sun, save moisture and keep soil temperature low.
Seed Selection for Growing Carrots
Preparing the soil before planting can prevent carrots from becoming stunted or misshapen. The success of carrots depends on this first stage.
It’s important to remove any stones or pebbles that could impede the growth of square roots. Carrots thrive in humus-rich soil that can be readily managed in raised beds, deep pots, or grow bags.
The 5 Major Carrot Varieties
As seen below, each carrot cultivar has unique growing requirements. Most seed packets will give you the needed advice on planting carrots.
The difference in days to maturity is due to hundreds of hybrids, each with unique development profiles. Not all carrots are the same, so plant carrots according to the seed supplier’s advice.
The table below is a generalized guide showing that when you plant carrots, one size does not fit all. Consideration of the carrot variety’s girth should inform the number of inches apart and air circulation around carrot foliage.
| Types | Length inches (cm) | Seed SpacingInches apart (cm) | Row SpacingInches apart (cm) | Days to Maturity |
|---|---|---|---|---|
| Chantenay | 4 – 7(10 – 18) | 0.5, thin to 1 to 2(1, thin to 2 to 5) | 12 (30) | 65 – 75 |
| Imperator | 7 – 8(18 – 20) | 1, thin to 2 to 3(2.5, thin to 5 to 13) | 18 (45) | 70 |
| Danvers | 7 (18) | 0.5, thin to 1 to 2(1, thin to 2 to 5) | 12 (30) | 75 |
| Nantes | 6 – 7(15 – 18) | 0.5, thin to 1 to 2(1, thin to 2 to 5) | 12 (30)(30) | 32 – 75 |
| Oxheart | 2 – 3(5 – 8) | 3 – 5 (8 – 13) | 12 to 18(30 – 45) | 90 |
Carrots Planting Tips
Grow carrots from seed in raised beds. Do not attempt to produce seeds for planting, as these can carry fungi and bacteria into new crops. Carrots are biennials rooting in year one and seeding the next.
If carrot flowers appear in year one, it’s called bolting and is usually caused by a sudden rise in temperatures.
Bed Preparation
Start bed preparations early in autumn if you want to seed in spring. Remember that you need a bed that hasn’t seen a plant from the Apiaceae family for at least three years.
The Apiaceae family includes carrots, celery, fennel, parsnips, and several herbs.
In early spring, cover the bed with about four to five inches of compost in preparation for growing carrots.
Before you plant your carrot seeds in situ, cover the compost with about an inch of soil. You don’t need to dig it in; the microorganisms in the compost will incorporate the soil into the compost.
Seed Planting
Ensure your garden soil is at least 70°F/21°C, but ideally 77°F/25°C before planting seeds, opting for pelleted seeds that are certified disease free.
You can plant carrot seeds earlier, but there’s little advantage as seeds in the soil at the lowest 50°F/10°C will take three weeks to germinate, whereas seeds sprout in a week in the soil at 77°F/25°C.
Using Luke-Warm Water
Once you have planted the seed as instructed on the seed packet, you should get some warm water (68 -77 °F/20 – 25 °C) ready. Use warm water to hydrate newly planted seeds.
Keeping the soil moist can help the seeds germinate more quickly. Warm water helps control cavity spots and damping off caused by Pythium oomycetes.
Keep Seeds From Dehydrating
Ensuring the carrot seeds never dry out is essential to growing new carrot plants. Sow seeds and cover the bed with burlap fabric, ensuring you cover the seeds.
Since the fabric is permeable, it acts as a mulch, allowing you to water the soil while limiting evaporation. To check on the progress of the seedlings, pull back the cloth; once the seeds have sprouted, they must be removed entirely.
Row Covers to Guard Against Carrot Pests
Once the foliage has sprouted, you can use row covers (net) to protect the plants or transparent row covers to manage pests and soil temperatures.
Lifting the row cover at intervals will be necessary to thin out the surplus, crowded carrot seedlings and eradicate weeds competing with the carrots for water and nutrients.
Risk Prevention
When you grow carrots, avoid growing sunflowers which offer nesting opportunities to carrot weevil beetles. Another tip is to grow carrots in a bed that previously had sweet corn growing in it.
Sweet corn and other grass grain crops help manage nematodes, one of the biggest challenges to growing carrots; root-knot nematodes cause root galls.
Carrot Water Needs
A flourishing vegetable garden can be attributed to good watering habits. Carrots prefer full sun and consistently moist soil.
Of essential importance is that seeds and young carrot seedlings are kept continually moist. Once there’s root growth, watering is again important.
The taproots need more water to avoid stress and to bolt as they lengthen and extend. If you want your carrots to mature on time, you need to start giving them 2 inches (50 mm) of water every week around the time they reach the halfway point.
Carrot Fertilization
As far as possible, grow carrots without using nitrogen. Too much nitrogen fertilizer promotes foliage growth and impedes root development. Keep phosphorus levels in check as well; too much of it might trigger root elongation and even root splitting.
Low Fertility Soil
Recommendations are for low fertility soil in a 4 x 10-foot bed (1.2 x 3 m) and represent the total needs per season.
Please do not exceed recommendations and subtract any nitrogen values that might be soil-borne due to organic matter and legume cover crops. Start with less and respond to your plant’s needs.
Distributed feeding is better than occasional bulk feeding unless you are boosting base in-soil fertility before planting, as informed by current valid soil-test results.
| CROP | N Starter | N Sidedressing | Phosphorus (P) | Potassium (K) |
|---|---|---|---|---|
| Carrots | 0.44 oz 12.11 g | 0.44 oz 12.11 g | 1.47 oz 40.35 g | 1.47 oz 40.35 g |
In case the numbers above seem small, the recommended starter application of nitrogen for carrots is 30 pounds per acre (start application). There are 43,560 square feet per acre and 16 ounces per pound.
30 pounds divided into 43,560 gives you 0.000689 pounds per square foot or 0.0110193 ounces. A bed measuring 10 x 4 = 40 square feet will need 0.440771 ounces of nitrogen.
Please note that the recommendations are for actual nitrogen, 10-10-10 mix only offers 10% nitrogen. A 0.44 oz. The application will need 4.4 ounces of fertilizer for a 40 sq. ft. bed or 121 grams for a 3.6m bed.
Carrot Pests and Diseases
Plants included in the root and tuber vegetable group are Beet, Carrot, Horseradish, Parsnip, Potato, Radish, Rutabaga, Sweet Potato, Turnip, and Yams.
Pest Common to Root and Tuber Vegetable Crops
Pests affecting carrot crops are aphids, carrot weevil beetles, carrot rust fly, caterpillars (cutworms), flea beetles, leafhoppers, nematodes, and seed and root maggots.
Aphids, leafhoppers, and nematodes are closely related to several carrot diseases. Nematodes (microscopic worms) can be avoided if carrots are planted after a maize crop.
Floating Row Covers (Again)
Leaf pests that carry diseases avoid carrots altogether if you cover your plants with floating row cover before they grow. Carrots don’t need pollination so a row cover can stay on for the growing season.
Carrot Diseases
| DISEASE | PATHOGEN |
|---|---|
| Carrot yellows | Phytoplasma mollicutes |
| Cavity spot | Pythium oomycetes |
| Damping-off seed and seedling rots | Various pathogens, incl. Fusarium spp. and Pythium spp. |
| Leaf Blight | Xanthomonas Bacteria and Alternaria fungus |
| Leaf Spot | Cercospora fungus, Ramularia cynarae |
| Nematodes | Several nematode species |
| Viruses | Several species |
| White Rust | Albugo oomycete |
5 Steps to Avoid Carrot Diseases
- Ensure the soil has sufficient drainage and organic matter. Healthy compost goes a long way in improving a plant’s resilience.
- Ensure enough space between carrots to ensure good airflow around the foliage.
- Manage pests and weeds – use floating covers and remove host weeds.
- Don’t plant succession crops of any plant family. The gap should be three years between any given family. Rotate your garden in four-year cycles per plant family.
- Avoid wetting plant foliage as far as possible. Don’t work with wet crops.
How to Harvest Carrots
Harvest carrots by pulling the entire plant from the ground. Finger carrots are ready to harvest when the top of the root is half an inch (13 mm), generally about 50 days after planting.
Carrots planted at the same time will be full size about two weeks later, and harvesting carrots may continue for up to a month. A straw mulch will let you harvest carrots directly from the garden until the ground freezes.
In Closing
I hope your next crop of carrots will come from a thriving garden. Pay special attention to using healthy organic potting soil if you want to grow carrots using container gardening.
