How to grow carrots: a commercial guide

Pick the carrot type for the market

Prepare a fine seedbed

Soil

Loose, deep, well-drained soil gives straight roots. Stones and compaction fork or stunt roots. Keep pH at 6.0–6.8.¹

Nematodes and history

Northern root-knot nematode has an outsized effect on carrots, and carrot cyst nematode feeds only on carrots. Sample before planting and rotate.¹

Sow and establish the stand

Timing

Sow when soil reaches about 4°C (40°F) in the northern Plains, from mid-April into June. Fall crops are sown 10–12 weeks before first frost.^2,3

Depth and moisture

Cover seed with 6–13 mm (¼–½ inch) of soil and keep the seedbed evenly moist until emergence; crusting is the main stand-loss risk.^2,3

Seed rate and spacing

Drill in single rows 41–76 cm (16–30 inches) apart, or three-row beds 25–30 cm (10–12 inches) apart on 91 cm (36-inch) centres. Aim for 65–100 plants per m (20–30 plants per foot) for fresh-market slicing and 10–20 for dicing; 2.2–4.5 kg of seed/ha (2–4 lb of seed per acre).¹

Fertility and water

Nitrogen

Apply about 65 kg N/ha (60 lb N/acre) before planting and sidedress 34–65 kg/ha (30–60 lb/acre) N 4–6 weeks after planting. Total N from fertilizer and credits should be about 110 kg/ha (100 lb/acre) for fresh-market and 120 for processing carrots on mineral soils, 56 kg/ha (50 lb/acre) less on muck.¹

Phosphorus and potassium

Apply 0–180 kg/ha (0–160 lb/acre) P2O5 and 0–225 kg K2O/ha (0–200 lb K2O per acre) according to the soil test. On muck soil above pH 6.0, add 6.7 kg manganese sulfate/ha (6 lb manganese sulfate per acre) over the row.¹

Water

At least about 2.5 cm (1 inch) a week from rain or irrigation; dry-wet swings produce misshapen, bitter roots.³

Protect the tops and the roots

Leaf blights

Alternaria and Cercospora leaf blights are sprayed from first detection; the TOM-CAST model (15 disease severity values) can time applications. Bacterial leaf blight follows hot, wet weather and can prevent harvest.¹

Cavity spot and aster yellows

Pythium cavity spot downgrades roots. Aster yellows is spread by leafhoppers; use disease-free seed (hot-water treatment 50°C (122°F) for 20 minutes) and control leafhoppers before they feed.¹

Follow labels

Fungicide and insecticide choices change by registration; check your current state label rather than an old product list.¹

Harvest, cool and store

When

Midwest carrots are harvested roughly August to November, when roots reach market size (about 19 mm (¾ inch) across at the shoulder is a common fresh-market minimum). Top-pullers break fewer roots than undercutting chain harvesters.^1,2

Cool quickly

Remove field heat rapidly (hydrocooling is recommended) and keep roots away from ethylene; as little as 0.5 ppm causes bitterness within about two weeks.⁴

Storage

Topped roots store at 0°C (32°F) with very high humidity. UC Davis reports 7–9 months at 98–100% RH for mature roots. Free water from washing or condensation promotes decay.⁴

Economics

Yields and prices vary too much by market to quote one figure. Iowa State publishes a carrot enterprise budget you can open and edit; start from it and replace the prices and yields with your own buyer terms.

Frequently asked questions

When do you plant carrots?

As soon as soil reaches about 4–7°C (40–45°F), from mid-April in the northern US into June, then again 10–12 weeks before first frost for a fall crop.

How deep do you sow carrot seed?

6–13 mm (¼–½ inch), kept evenly moist until emergence.

How long do carrots take to grow?

Commercial guidance ranges from about 60 days for baby carrots to 120 days for full-size Danvers types; variety, market size and season length affect the harvest date.

What soil pH do carrots need?

pH 6.0–6.8 in commercial guidance, in deep, loose, stone-free soil.

How long can carrots be stored?

At 0°C (32°F) and 98–100% humidity, UC Davis reports 7–9 months for mature roots. Actual storage life depends on variety, maturity and postharvest handling.