Collard Greens Companion Plants
Brassica oleracea var. viridis · mustard family family · rotation group: brassica
The best companion plants for collard greens are Mustard (perimeter trap crop), Arugula (alternative trap plant), Cabbage, Sweet alyssum, and White clover (undersown living mulch). Avoid planting collard greens near Other brassicas, Strawberry, Pole bean, Tomato. Of the 12 pairings recorded here, 5 are supported by published research and 6 are traditional practice with no controlled evidence behind them.
What to plant with collard greens
| Plant | Claimed benefit | Evidence | What the evidence actually shows |
|---|---|---|---|
| Arugula (alternative trap plant) | Arugula, rapini and rapeseed also draw harlequin bugs away from collards. | Research-backed | In the same replicated host-preference study, mustard, rapeseed, rapini and arugula were all significantly more attractive to harlequin bug than collard. Mustard was the most consistently preferred and is the only one taken through to field trap-crop trials, so arugula is a supported second choice rather than a proven substitute. |
| Cabbage | Collards planted as a border protect a cabbage crop by absorbing the diamondback moth pressure. | Research-backed | Here collards are the trap crop, not the protected crop. Screenhouse trials found diamondback moth laid 3-18x more eggs on glossy collards, waxy collards and Indian mustard than on cabbage when given a choice, and UF/IFAS lists collards as a trap crop for diamondback moth on cabbage. Larvae do survive on collards, so unlike a dead-end trap this needs the trap row treated or the collards themselves take heavy damage. |
| Mustard (perimeter trap crop) | A perimeter row of mustard pulls harlequin bugs off the collards and concentrates them where they can be killed. | Research-backed | This is one of the best-evidenced pairings in vegetable gardening. Choice tests showed harlequin bug consistently prefers mustard over collard; field trials at two sites showed mustard borders reduced feeding damage, with spring collards holding under 1% leaf damage. A follow-up found spacing matters: a 2.3 m gap between mustard and collards cut egg-laying on collards about fourfold and damage about 2.5-fold versus an adjacent trap row, because females otherwise commute across to lay. Requires scouting and killing the bugs on the trap crop. |
| Sweet alyssum | Strips of flowering alyssum near collards build up hoverflies, lady beetles and parasitoid wasps that suppress aphids and caterpillars. | Research-backed | A replicated organic cabbage study using a glossy-collard trap mix found insectary alyssum significantly raised parasitism of the cross-striped cabbageworm and the abundance of predatory lady beetle eggs and larvae. Note this is measured as natural-enemy activity and pest suppression, not as a yield increase, and it works as a strip rather than a couple of scattered plants. |
| White clover (undersown living mulch) | Collards undersown with a low living clover receive fewer cabbage root fly eggs and less aphid colonisation. | Research-backed | Repeated cage and field work reduced cabbage root fly egg counts in clover-undersown brassicas. The decisive control: brown desiccated clover gave no protection while living green clover did, so the mechanism is disrupted host-plant finding over a green background rather than any repellent chemistry. The trade-off is real competition for water and nitrogen, so undersow only once collards are established and expect to irrigate more. |
| Dill | Dill flowers supply nectar to the parasitoid wasps that attack cabbageworms and aphids on collards. | Traditional | The nectar-subsidy mechanism is well established for insectary plants in general, but the species actually trialled in brassica systems are sweet alyssum and buckwheat. Dill specifically has not been tested here, and extension companion charts confusingly list dill both as a beneficial-insect plant and as something to keep away from cabbage-family crops. |
| Nasturtium | Nasturtium is grown as a sacrificial magnet for aphids and cabbage white butterflies. | Traditional | Nasturtium is a genuine host for both pests so the idea is plausible, but the brassica trap-crop literature that has actually been trialled uses mustard, kale, collards and yellow rocket. No replicated data supports nasturtium in this role. |
| Thyme | Aromatic herbs like thyme, sage and mint are said to repel cabbage moths from collards. | Not supported | Tested and not supported in the form usually claimed. Experiments comparing aromatic against non-aromatic companion plants around brassicas found aromatic species were no better than ordinary green plants, and aromatic plants did not repel the flies so much as interrupt their host-selection sequence; dried plant material produced no effect at all. Any benefit comes from green ground cover, not from thyme's scent. |
What not to plant with collard greens
| Plant | Claimed problem | Evidence | What the evidence actually shows |
|---|---|---|---|
| Other brassicas | Growing collards next to or after other cabbage-family crops concentrates shared pests and builds up soil diseases. | Traditional | The rotation half is firm extension practice — black rot, Alternaria leaf spot, clubroot and Fusarium yellows persist in soil and debris, so brassicas are kept out of a bed for several years. The same-season adjacency penalty is inferred from that rather than measured, and it partly conflicts with the trap-cropping evidence, where deliberately planting a more attractive brassica nearby protects the crop. |
| Pole bean | Pole beans are listed as a plant to keep away from cabbage-family crops. | Traditional | Untested. The only defensible objection is physical: a bean trellis shades collards and blocks the row cover that is the main non-chemical defence against cabbageworms and flea beetles. The nutrient-competition story does not hold up either way without measurement. |
| Strawberry | Strawberries are listed among plants not to grow near cabbage-family crops. | Traditional | Chart folklore repeated across extension and garden publications with no trial behind it; the source itself notes companion planting is not an exact science. There is no measured yield, growth or pest effect for collards and strawberry. |
| Tomato | Tomatoes are said to compete with collards because both are heavy feeders. | Traditional | No trial supports it. Both crops are in fact heavy nitrogen feeders — Clemson recommends repeat side-dressing of collards with calcium nitrate — so competition is plausible if they are crowded, but it is a fertility and spacing question that fertiliser and 30-inch rows solve, not an inherent incompatibility. |
The honest verdict
Of everything gardeners recommend planting alongside collard greens, 5 pairings have been tested properly: Mustard (perimeter trap crop), Arugula (alternative trap plant), Cabbage, Sweet alyssum, White clover (undersown living mulch). Those are the ones worth planning your bed around.
The remaining 2 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: Thyme — Tested and not supported in the form usually claimed. Experiments comparing aromatic against non-aromatic companion plants around brassicas found aromatic species were no better than ordinary green plants, and aromatic plants did not repel the flies so much as interrupt their host-selection sequence; dried plant material produced no effect at all. Any benefit comes from green ground cover, not from thyme's scent.
Every row above links to the publication it came from. See how we grade evidence.
Growing collard greens: the numbers
| Sun | Full sun (6+ hours) |
|---|---|
| Water | Moderate |
| Spacing | 12 in apart · 30 in between rows · 1 per square foot |
| Mature size | about 30 in tall |
| Soil pH | 6–6.5 |
| Days to maturity | 60–80 days |
| Frost tolerance | Hardy — takes hard frost |
| Containers | Yes — 5 gallon minimum |
| Typical yield | repeated leaf harvests over 2-3 months |
| Common pests | imported cabbageworm, cabbage looper, diamondback moth, harlequin bug, aphid, flea beetle, cabbage maggot |
| Common diseases | black rot, downy mildew, Alternaria leaf spot, Fusarium yellows, clubroot |
When to plant collard greens
Zone 6b shownStart seeds indoors: Feb 27 – Mar 13 — 4–6 weeks before your last frost
Transplant outdoors: Mar 27 – Apr 9 — 2 weeks before last frost
Direct sow outdoors: Mar 27 – Apr 9 — 2 weeks before last frost
Expected harvest: May 26 – Jun 15 — 60–80 days from planting
Fall planting: Aug 4 – Aug 17 — 12 weeks before your first fall frost
Those dates are for zone 6b. Get your own dates by ZIP code →
Varieties worth knowing
seeds- Georgia Southern — Heirloom non-heading type recommended by Clemson and NC State Extension; loose open plant, long-standing in the South.
- Vates — Heirloom listed by both Clemson and NC State Extension; compact, low-growing and slow to bolt.
- Flash — Hybrid recommended by Clemson Extension; noted for quick regrowth after leaf picking, suiting cut-and-come-again harvest.
- Top Bunch 2.0 — Hybrid recommended by Clemson Extension; upright habit bred for repeated bunch harvest, within the 60-80 day range.
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 collard greens next to something recorded as a bad neighbour, the square turns red and tells you why.
Records for the plants named above:
Same rotation group (brassica) — don't follow one with another:
Collard Greens companion planting questions
What should not be planted next to collard greens?
How far apart should collard greens be planted?
Does companion planting with collard greens actually work?
When should I plant collard greens?
Sources for this record
- Clemson Cooperative Extension HGIC — Collards
- NC State Extension — Collard Greens
- UMN Extension — Growing collards and kale in home gardens
- Illinois Extension — Collard
- UMN Extension — Planting vegetables in midsummer for fall harvest
Record compiled 2026-07. Spot an error or a study we missed? Tell us and we'll correct the entry.