Record — updated 2026-07

Parsley Companion Plants

Entry No. 049

Petroselinum crispum · carrot family family · rotation group: other

The best companion plants for parsley are Tomato, Asparagus, Pepper, Onion, and Brassicas. Avoid planting parsley near Carrot, Lettuce. Of the 7 pairings recorded here, 0 are supported by published research and 7 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 parsley

Companion plants for parsley — 0 research-backed, 5 traditional
Plant	Claimed benefit	Evidence	What the evidence actually shows
Asparagus	Parsley is a classic interplant in permanent asparagus beds.	Traditional	Works practically because parsley is shallow-rooted and shade-tolerant; no measured benefit to asparagus. Source: Growing parsley in home gardens, University of Minnesota Extension
Brassicas	Parsley flowers feed the parasitoids that attack cabbage aphids.	Traditional	Same umbellifer nectar mechanism proven for dill and cilantro, but parsley itself was not among the plants tested. Source: Ballew, J. (2022), Attracting Beneficial Insects to Your Vegetable Garden, Clemson HGIC
Onion	Onions and parsley interplant without competing for root space.	Traditional	Compatible root architecture; no biological interaction shown. Source: Parsley, Illinois Extension Herbs
Pepper	Parsley provides living ground cover at the base of peppers.	Traditional	A sensible space-use pairing; the pest benefit is unverified. Source: Petroselinum crispum, NC State Extension Gardener Plant Toolbox
Tomato	Parsley left to flower in its second year draws parasitoid wasps and hoverflies to the tomato bed.	Traditional	Clemson lists parsley among small-flowered insectary plants, but parsley only flowers in year two and the tomato pairing is untested. Source: Ballew, J. (2022), Attracting Beneficial Insects to Your Vegetable Garden, Clemson HGIC

What not to plant with parsley

Plants to keep away from parsley
Plant	Claimed problem	Evidence	What the evidence actually shows
Carrot	Same-family crop sharing carrot weevil and leaf-spot pathogens.	Traditional	Rotation logic rather than a demonstrated antagonism; keep Apiaceae crops grouped for rotation purposes. Source: Petroselinum crispum, NC State Extension Gardener Plant Toolbox
Lettuce	Parsley is said to inhibit nearby lettuce.	Traditional	Appears in older companion charts with no supporting trial; treat as unverified folklore. Source: Parsley, Illinois Extension Herbs

The honest verdict

None of the companion pairings commonly recommended for parsley have been confirmed in controlled trials that we could find. That does not make them harmful — it means the benefit is unproven, and you should plant for spacing, sun, and water compatibility first.

The remaining 5 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.

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

Other recorded effects

Effects that aren't about a neighbouring plant — what parsley does for (or to) the garden around it, and the caveats attached to the popular versions of those claims.

Recorded effects and caveats — Parsley
Effect	The claim	Evidence	What the evidence actually shows
Black Swallowtail Butterfly	Parsley is a larval host plant for black swallowtail butterflies.	Research-backed	Well documented host-plant relationship; plant extra if you want the caterpillars, since they will strip foliage. Source: Petroselinum crispum, NC State Extension Gardener Plant Toolbox

Growing parsley: the numbers

Field data — Parsley
Sun	Full sun (6+ hours)
Water	Moderate
Spacing	10 in apart · 18 in between rows · 4 per square foot
Mature size	about 18 in tall
Soil pH	6–7
Days to maturity	70–80 days
Frost tolerance	Hardy — takes hard frost
Containers	Yes — 2 gallon minimum
Common pests	carrot weevil, leaf miners, flea beetles, leafhoppers
Common diseases	septoria leaf spot, stem rot

When to plant parsley

Zone 6b shown

Start indoors Sow / transplant outdoors Harvest

Start seeds indoors: Feb 13 – Feb 27 — 6–8 weeks before your last frost

Transplant outdoors: Apr 10 – Apr 23 — around your last frost date

Direct sow outdoors: Apr 10 – Apr 23 — around your last frost date

Expected harvest: Jun 19 – Jun 29 — 70–80 days from planting

Fall planting: Aug 18 – Aug 31 — 10 weeks before your first fall frost

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

Varieties worth knowing

seeds

Giant of Italy — flat-leaf Italian type; the standard for cooking
Darki — dark green curled type with good holding ability
Banquet — finely curled garnish type
Hamburg (var. tuberosum) — grown for its edible parsnip-like root

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 parsley next to something recorded as a bad neighbour, the square turns red and tells you why.

Records for the plants named above:

Tomato Asparagus Pepper Onion

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

Asparagus Celery Okra Rhubarb Sweet corn Sweet Potato

Parsley companion planting questions

What should not be planted next to parsley?

Carrot, Lettuce. Same-family crop sharing carrot weevil and leaf-spot pathogens. Rotation logic rather than a demonstrated antagonism; keep Apiaceae crops grouped for rotation purposes.

How far apart should parsley be planted?

Space parsley about 10 inches apart in the row, with 18 inches between rows. In a square-foot bed that works out to 4 plants per square foot.

Does companion planting with parsley actually work?

Partly. None of the pairings we found for parsley have been confirmed in controlled trials. 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 parsley?

Start seed indoors 6–8 weeks before your last frost. Transplant outdoors around your last frost date. In zone 6b that means roughly Apr 10 – Apr 23. 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.