Record — updated 2026-07

Lettuce Companion Plants

Entry No. 019

Lactuca sativa · aster family · rotation group: leafy

The best companion plants for lettuce are Sweet alyssum, Carrot, Radish, Onion and chives, and Pole bean. Avoid planting lettuce near Brassicas (cabbage, broccoli), Fennel, Sunflower. Of the 11 pairings recorded here, 1 is supported by published research and 10 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 lettuce

Companion plants for lettuce — 1 research-backed, 7 traditional
Plant	Claimed benefit	Evidence	What the evidence actually shows
Sweet alyssum	Alyssum interplanted with lettuce delivers biological control of lettuce aphids via hoverflies.	Research-backed	Backed by roughly a decade of USDA-ARS commercial-scale organic work in the Salinas Valley; as few as 500-1000 alyssum transplants per acre distributed through the field supplied enough pollen and nectar for hoverflies to control aphids in romaine. Source: Efficient Intercropping for Biological Control of Aphids in Transplanted Organic Lettuce, eOrganic / USDA-ARS
Carrot	Lettuce and carrots interleave well because they occupy different soil depths and seasons.	Traditional	Sensible spacing practice; no biological interaction has been tested. Source: Lettuce, Home Vegetable Gardening, University of Illinois Extension
Marigold	Marigold planted with lettuce repels aphids and slugs.	Traditional	Marigold's real results are whitefly protection on tomato and nematode suppression as a dedicated pre-crop; Rutgers work found marigolds failed to repel several vegetable pests, so treat this pairing sceptically. Source: Magical Repelling Powers of Marigolds - Myth or Fact?, Piedmont Master Gardeners, Virginia Cooperative Extension
Onion and chives	Alliums bordering lettuce deter aphids and rabbits.	Traditional	The documented allium intercropping effects are on carrot fly and onion thrips; nothing tests aphids on lettuce, and the vertebrate-deterrence claim has no support at all. Source: Uvah & Coaker 1984, Effect of mixed cropping on some insect pests of carrots and onions, Entomologia Experimentalis et Applicata
Pole bean	Tall crops shade summer lettuce and delay bolting.	Traditional	The underlying physiology is verified, since bolting is driven by temperatures above 75 F and long days, so afternoon shade genuinely helps; but no trial compares lettuce grown behind pole beans against lettuce in the open. Source: Growing lettuce, endive and radicchio in home gardens, University of Minnesota Extension
Radish	Fast radishes are harvested out from between lettuce before it needs the room.	Traditional	A timing convention, not a pest or growth claim. Source: Lettuce, Home Vegetable Gardening, University of Illinois Extension
Strawberry	Lettuce fills the gaps in a young strawberry planting.	Traditional	Space-sharing in the establishment year; no interaction claimed or tested. Source: Growing strawberries in the home garden, University of Minnesota Extension
Tomato	Lettuce grows in the shade of staked tomatoes through early summer.	Traditional	A practical use of the shade a tomato cage casts; not a tested pest or growth benefit. Source: Companion Planting: Anecdotal or Tried and Tested?, University of Illinois Extension

What not to plant with lettuce

Plants to keep away from lettuce
Plant	Claimed problem	Evidence	What the evidence actually shows
Brassicas (cabbage, broccoli)	Brassicas next to lettuce concentrate cabbage loopers and armyworms on the salad crop.	Traditional	Cabbage looper and armyworm genuinely feed on lettuce as well as brassicas, so the shared-pest premise holds, but no trial shows that separating them reduces lettuce damage. Source: Home Garden Lettuce (C1018), University of Georgia Extension
Fennel	Fennel suppresses lettuce germination and growth.	Traditional	Fennel is allelopathic in laboratory germination bioassays; no garden-scale test against lettuce exists. Source: Gardening with Companion Plants (Home Garden Series), Washington State University Extension
Sunflower	Sunflower roots and hulls inhibit lettuce.	Traditional	Sunflower allelopathy is documented against some species in controlled assays, but the effect on garden lettuce has not been measured and heavy shading is the more likely practical problem. Source: Gardening with Companion Plants (Home Garden Series), Washington State University Extension

The honest verdict

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

The remaining 7 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.

Growing lettuce: the numbers

Field data — Lettuce
Sun	Full sun (6+ hours)
Water	Moderate
Spacing	8 in apart · 15 in between rows · 4 per square foot
Mature size	about 10 in tall
Soil pH	6–6.8
Days to maturity	50–70 days
Frost tolerance	Half-hardy — takes a light frost
Containers	Yes — 2 gallon minimum
Typical yield	0.3-0.6 lb
Common pests	aphids, slugs, flea beetles, cutworms, cabbage looper, leafminers
Common diseases	downy mildew, damping-off, gray mold (Botrytis), Sclerotinia drop, aster yellows

When to plant lettuce

Zone 6b shown

Start indoors Sow / transplant outdoors Harvest

Start seeds indoors: Feb 27 – Mar 13 — 4–6 weeks before your last frost

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

Transplant outdoors: Mar 27 – Apr 9 — 2 weeks before last frost

Expected harvest: May 16 – Jun 5 — 50–70 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

Black Seeded Simpson — loose leaf, classic fast green leaf type, 50-60 days
Buttercrunch — butterhead/Bibb, heat-tolerant for its class, 60-70 days
Parris Island Cos — romaine, upright cos head
Red Sails — loose leaf, red-tinged, slow to bolt

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

Records for the plants named above:

Sweet alyssum Carrot Radish Onion and chives Pole bean Strawberry Marigold Tomato

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

Spinach Swiss Chard

Lettuce companion planting questions

What should not be planted next to lettuce?

Brassicas (cabbage, broccoli), Fennel, Sunflower. Brassicas next to lettuce concentrate cabbage loopers and armyworms on the salad crop. Cabbage looper and armyworm genuinely feed on lettuce as well as brassicas, so the shared-pest premise holds, but no trial shows that separating them reduces lettuce damage.

How far apart should lettuce be planted?

Space lettuce about 8 inches apart in the row, with 15 inches between rows. In a square-foot bed that works out to 4 plants per square foot.

Does companion planting with lettuce actually work?

Partly. 1 of the pairings on this page are backed by published research — Sweet alyssum. 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 lettuce?

Start seed indoors 4–6 weeks before your last frost. 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.