Record — updated 2026-07

Carrot Companion Plants

Entry No. 009

Daucus carota var. sativus · carrot family · rotation group: root

The best companion plants for carrot are Onion, Leek, Radish, Lettuce, and Chives. Avoid planting carrot near Dill, Fennel, Parsnip and celery. Of the 11 pairings recorded here, 1 is supported by published research and 9 are traditional practice with no controlled evidence behind them.

Research-backed tested in controlled research Traditional long practice, untested Not supported tested and not supported

What to plant with carrot

Companion plants for carrot — 1 research-backed, 6 traditional
Plant	Claimed benefit	Evidence	What the evidence actually shows
Onion	Onions intercropped with carrots reduce carrot rust fly damage.	Research-backed	One of the very few companion pairings with real controlled data: mixed cropping cut carrot fly attack by up to 65 percent versus carrot monoculture, and also raised numbers of carabid and staphylinid predators of carrot fly eggs. Source: Uvah & Coaker 1984, Effect of mixed cropping on some insect pests of carrots and onions, Entomologia Experimentalis et Applicata
Chives	Chives deter carrot rust fly.	Traditional	Same allium mechanism as the proven onion pairing, but chives were not the species tested and the documented effect depended on allium planting density. Source: Uvah & Coaker 1984, Effect of mixed cropping on some insect pests of carrots and onions, Entomologia Experimentalis et Applicata
Leek	Leeks confuse carrot rust fly the way onions do.	Traditional	Plausible by extension of the onion result, which is genuinely well supported, but the 1984 trial used onion and the effect scaled with onion density, so do not assume leeks are equivalent. Source: Uvah & Coaker 1984, Effect of mixed cropping on some insect pests of carrots and onions, Entomologia Experimentalis et Applicata
Lettuce	Lettuce shades the soil surface and keeps carrot seed moist during germination.	Traditional	Consistent with the verified requirement to keep the carrot seedbed continuously moist, but nobody has trialled lettuce specifically as the shading crop. Source: Growing carrots and parsnips in home gardens, University of Minnesota Extension
Pea	Peas improve the soil for a following carrot crop.	Traditional	Legumes do add nitrogen, but the benefit arrives after residues decompose rather than during the season, so this works as a rotation choice and not as an interplanting. Source: Intercropping Legumes with Nonlegumes, SARE
Radish	Radish sown with carrots marks the row and breaks the soil crust during the long carrot germination.	Traditional	This is an extension-recommended practical technique rather than a pest claim: Texas A&M suggests mixing in fast-sprouting radish seed to mark the row through the 14-21 day carrot germination window. Source: Easy Gardening: Carrots (E-505), Texas A&M AgriLife Extension
Sage and rosemary	Strongly aromatic herbs mask the carrot scent that guides carrot rust fly.	Traditional	Sage and thyme do have real trial data behind them, but against diamondback moth on brassicas; the carrot fly application is untested. Source: Companion planting in home gardens, University of Minnesota Extension
Tomato	Tomatoes improve carrot growth and flavor.	Not supported	The famous claim behind Carrots Love Tomatoes (Riotte, 1975), a folk compilation containing no experiments or citations; no controlled trial has ever supported it. Source: Companion Planting: Anecdotal or Tried and Tested?, University of Illinois Extension

What not to plant with carrot

Plants to keep away from carrot
Plant	Claimed problem	Evidence	What the evidence actually shows
Dill	Dill near carrots stunts the roots and can cross with them.	Traditional	Both are Apiaceae so they share pests and can host carrot rust fly, but dill and carrot are different genera and do not cross-pollinate; the stunting claim has no data behind it. Source: Growing carrots and parsnips in home gardens, University of Minnesota Extension
Fennel	Fennel inhibits carrot germination and growth.	Traditional	Fennel essential oil suppresses germination in laboratory bioassays, which makes the claim plausible for a slow-germinating seed crop, but no garden trial tests it. Source: Gardening with Companion Plants (Home Garden Series), Washington State University Extension
Parsnip and celery	Other umbellifers next to carrots concentrate shared pests and diseases.	Traditional	The shared host range is real, and extension covers carrot and parsnip in a single publication for this reason, but no trial measures added damage from adjacency. Source: Growing carrots and parsnips in home gardens, University of Minnesota Extension

The honest verdict

Of everything gardeners recommend planting alongside carrot, 1 pairing has been tested properly: Onion. Those are the ones worth planning your bed around.

The remaining 6 pairings on this page are traditional practice. They circulate on every companion planting chart online, but we could not find controlled evidence testing them. They are not wrong so much as unverified — most cost nothing to try, and interplanting flowers and herbs has its own well-documented benefit of pulling pollinators and predatory insects into the garden.

Widely repeated, not supported: Tomato — The famous claim behind Carrots Love Tomatoes (Riotte, 1975), a folk compilation containing no experiments or citations; no controlled trial has ever supported it.

Every row above links to the publication it came from. See how we grade evidence.

Growing carrot: the numbers

Field data — Carrot
Sun	Full sun (6+ hours)
Water	Moderate
Spacing	3 in apart · 16 in between rows · 16 per square foot
Mature size	about 12 in tall
Soil pH	6–7
Days to maturity	60–80 days
Frost tolerance	Half-hardy — takes a light frost
Containers	Yes — 3 gallon minimum
Typical yield	about 1 lb of roots per foot of row
Common pests	carrot rust fly, cutworms, wireworms, root-knot nematodes, aster leafhopper
Common diseases	aster yellows, Alternaria leaf blight, root rot, cavity spot

When to plant carrot

Zone 6b shown

Start indoors Sow / transplant outdoors Harvest

Direct sow outdoors: Mar 20 – Apr 2 — 3 weeks before last frost

Expected harvest: May 19 – Jun 8 — 60–80 days from planting

Fall planting: Aug 11 – Aug 24 — 11 weeks before your first fall frost

Those dates are for zone 6b. Get your own dates by ZIP code →

Varieties worth knowing

seeds

Danvers 126 — classic tapered main-crop type, tolerates heavier soil
Nantes — cylindrical blunt-tipped, sweet and tender
Chantenay — short broad-shouldered, best choice for shallow or heavy soil
Sugarsnax — sweet slender hybrid, high carotene

Variety names link to seeds on Amazon. As an Amazon Associate we earn from qualifying purchases. These are the varieties named in the extension sources for this crop, not a paid placement — where a source recommended a variety for a specific reason, that reason is the note beside it.

Put it in a bed

The garden planner checks every square against this ledger as you place crops — if you drop carrot next to something recorded as a bad neighbour, the square turns red and tells you why.

Records for the plants named above:

Onion Tomato Leek Radish Lettuce Chives Sage and rosemary Pea

Same rotation group (root) — don't follow one with another:

Beet Parsnip

Carrot companion planting questions

What should not be planted next to carrot?

Dill, Fennel, Parsnip and celery. Dill near carrots stunts the roots and can cross with them. Both are Apiaceae so they share pests and can host carrot rust fly, but dill and carrot are different genera and do not cross-pollinate; the stunting claim has no data behind it.

How far apart should carrot be planted?

Space carrot about 3 inches apart in the row, with 16 inches between rows. In a square-foot bed that works out to 16 plants per square foot.

Does companion planting with carrot actually work?

Partly. 1 of the pairings on this page are backed by published research — Onion. The rest are traditional practice: plausible, harmless to try, but untested. Treat the folklore as a starting point rather than a rule, and read what the evidence says about companion planting.

When should I plant carrot?

Direct sow outdoors 3 weeks before last frost. In zone 6b that means roughly Mar 20 – Apr 2. Get exact dates for your ZIP code →

Sources for this record

Record compiled 2026-07. Spot an error or a study we missed? Tell us and we'll correct the entry.