{
  "name": "Companion Planting Pairs — evidence-rated crop relationships",
  "description": "Open reference table of vegetable-garden companion and antagonist pairings: each crop, the partner crop, whether the relationship helps or hurts, the strength of the evidence (strong / moderate / traditional), and the reasoning. Free CSV + JSON, CC-BY 4.0.",
  "url": "https://www.getgrowli.app/data/companion-planting",
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "creditText": "Companion-planting reference table compiled by Growli (getgrowli.app), CC-BY 4.0, from peer-reviewed horticulture research and US extension guidance, with evidence strength labelled per pairing.",
  "sources": [
    "Peer-reviewed horticulture journals cited per row (e.g. Plant Cell Reports)",
    "US Cooperative Extension System intercropping trials and guidance"
  ],
  "methodology": "Each pairing is classified by evidence strength: \"strong\" = replicated peer-reviewed research or strong extension consensus; \"moderate\" = a single peer-reviewed study or strong extension guidance; \"traditional\" = long-standing gardener practice with limited formal evidence. The reasoning column states the mechanism and, where one exists, the specific study or extension trial. Pairings without research support are labelled traditional rather than asserted as fact.",
  "spatialCoverage": "US, GB",
  "lastVerified": "2026-05-15",
  "recordCount": 92,
  "data": [
    {
      "crop": "Basil",
      "relationship": "Antagonist",
      "partner": "Cucumbers",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Strongly aromatic herbs — including basil, sage, and mint — can taint cucumber flavour according to multiple extension sources, and basil's shallow roots compete for the same surface moisture that cucumbers need. Plant cucumbers in a separate bed."
    },
    {
      "crop": "Basil",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Basil grows tall enough to give lettuce some afternoon shade in zones 7+, extending the lettuce season by 2-3 weeks. Both want consistent moisture and similar soil pH."
    },
    {
      "crop": "Basil",
      "relationship": "Companion",
      "partner": "Peppers",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Basil repels thrips, aphids, and whiteflies common on peppers; peppers in turn provide light shade that slows basil bolting in midsummer. Plant 12 inches apart so neither shades the other heavily."
    },
    {
      "crop": "Basil",
      "relationship": "Companion",
      "partner": "Tomatoes",
      "evidence": "Strong (replicated / peer-reviewed)",
      "reasoning": "The best-documented herb-vegetable companion pair. Basil volatiles prime tomato defence genes (Plant Cell Reports, 2024) and intercropped beds show measurable yield lifts versus monoculture."
    },
    {
      "crop": "Bush beans",
      "relationship": "Antagonist",
      "partner": "Garlic",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium-Rhizobium interference as onions. Multiple extension sources recommend keeping bush beans and garlic at least 2-3 rows apart."
    },
    {
      "crop": "Bush beans",
      "relationship": "Antagonist",
      "partner": "Onions",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Alliums release sulfur compounds (allicin) that suppress the Rhizobium bacteria bush beans rely on for nitrogen fixation. Bean roots near onion rows show measurably reduced nodulation."
    },
    {
      "crop": "Bush beans",
      "relationship": "Antagonist",
      "partner": "Peppers",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Excess nitrogen from beans can over-stimulate pepper foliage at the expense of fruit set if the bed is already moderately fertile. Better separated."
    },
    {
      "crop": "Bush beans",
      "relationship": "Antagonist",
      "partner": "Tomatoes",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Tomatoes are heavy feeders that compete with beans for water and nutrients in dry stretches. Not a hard incompatibility, but most planning charts recommend separate beds for these two."
    },
    {
      "crop": "Bush beans",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Carrots dig deep, beans stay mid-depth — they share the bed without root competition. Beans leave nitrogen for the heavy-leafed carrots-after-beans rotation."
    },
    {
      "crop": "Bush beans",
      "relationship": "Companion",
      "partner": "Cucumbers",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Beans fix nitrogen that cucumbers (heavy feeders) immediately use. Bush bean foliage also helps shade the soil to suppress cucumber-beetle activity."
    },
    {
      "crop": "Bush beans",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Bush beans fix nitrogen that the next lettuce sowing draws on; lettuce roots are shallow so they don't compete with bean roots underground."
    },
    {
      "crop": "Bush beans",
      "relationship": "Companion",
      "partner": "Peas",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Same family, same nitrogen-fixing biology. Stagger the planting (peas in spring, bush beans 4-6 weeks later) so both crops use the same trellis space sequentially."
    },
    {
      "crop": "Bush beans",
      "relationship": "Companion",
      "partner": "Radishes",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Radishes mature fast (25-30 days) and pull out before bush beans need the surface space. Their roots also break up compacted soil for the bean root system."
    },
    {
      "crop": "Bush beans",
      "relationship": "Companion",
      "partner": "Spinach",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Spinach finishes its cool-season cycle just before bush beans peak — perfect succession timing, and spinach leaves nitrogen-friendly residue."
    },
    {
      "crop": "Carrots",
      "relationship": "Companion",
      "partner": "Garlic",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same sulfur-volatile mechanism as onions — garlic disrupts carrot fly host-finding behaviour. Garlic also overwinters in the same bed and harvests out before carrots peak, so there is no late-season competition."
    },
    {
      "crop": "Carrots",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Lettuce occupies the soil surface while carrots dig deep, so they share the bed without competing. Both like cool weather and even moisture."
    },
    {
      "crop": "Carrots",
      "relationship": "Companion",
      "partner": "Onions",
      "evidence": "Strong (replicated / peer-reviewed)",
      "reasoning": "The most evidence-backed carrot pairing. Mixed-row plantings have been shown to reduce carrot fly egg-laying by up to 70% (University of Bristol Botanic Garden). The two crops mask each other's scent and confuse both carrot fly and onion fly."
    },
    {
      "crop": "Carrots",
      "relationship": "Companion",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Peas fix nitrogen and finish their cycle while carrots are still bulking up — perfect rotation timing. Pea trellises also cast light shade that keeps carrot soil cool."
    },
    {
      "crop": "Carrots",
      "relationship": "Companion",
      "partner": "Peppers",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Same logic as the tomato pairing — peppers shade the soil, carrots use the cool ground. No root competition because the depth profiles differ."
    },
    {
      "crop": "Carrots",
      "relationship": "Companion",
      "partner": "Radishes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes germinate in 5 days and mature in 25-30 — pulling them out marks the slow-germinating carrot rows and loosens the soil surface for delicate carrot seedlings."
    },
    {
      "crop": "Carrots",
      "relationship": "Companion",
      "partner": "Tomatoes",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "A famous traditional pairing (Louise Riotte's \"Carrots Love Tomatoes\") with limited peer-reviewed support. Tomato canopies do provide useful afternoon shade for carrots in warm zones, but treat the yield-boost claim as folklore."
    },
    {
      "crop": "Cucumbers",
      "relationship": "Antagonist",
      "partner": "Basil",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Strongly aromatic herbs (basil, sage, mint) can taint cucumber flavour according to multiple extension sources, and basil's shallow roots compete with cucumber roots for surface moisture."
    },
    {
      "crop": "Cucumbers",
      "relationship": "Companion",
      "partner": "Bush beans",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Beans fix nitrogen that cucumbers, as heavy feeders, readily use; bean foliage also helps shade the soil and suppress cucumber-beetle eggs. Plant bush varieties so they don't compete for the trellis."
    },
    {
      "crop": "Cucumbers",
      "relationship": "Companion",
      "partner": "Garlic",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Same allium logic as onions — sulfur compounds suppress aphids and spider mites. Garlic finishes harvesting in early summer, just as cucumbers ramp up."
    },
    {
      "crop": "Cucumbers",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Lettuce uses the cool, shaded ground beneath maturing cucumber vines, extending the lettuce season. Both prefer consistent moisture."
    },
    {
      "crop": "Cucumbers",
      "relationship": "Companion",
      "partner": "Onions",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Onion volatiles deter aphids and some cucumber-beetle activity. Plant onions on the bed edges so the trellised cucumbers don't shade out the alliums."
    },
    {
      "crop": "Cucumbers",
      "relationship": "Companion",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Peas finish their spring cycle just as cucumbers go in, leaving nitrogen-enriched soil. Use the same trellis structure for both crops in succession."
    },
    {
      "crop": "Cucumbers",
      "relationship": "Companion",
      "partner": "Radishes",
      "evidence": "Strong (replicated / peer-reviewed)",
      "reasoning": "Radishes act as a trap crop for cucumber beetles and flea beetles — interplanted radish foliage takes the early-season beetle pressure. Cornell Cooperative Extension recommends 2-3 radish seeds in each cucumber hill."
    },
    {
      "crop": "Garlic",
      "relationship": "Antagonist",
      "partner": "Bush beans",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium-Rhizobium interference as peas — garlic's sulfur compounds suppress the bacteria bush beans need for nitrogen fixation. Separate beds is the safer call."
    },
    {
      "crop": "Garlic",
      "relationship": "Antagonist",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Allicin disrupts the Rhizobium bacteria peas rely on for nitrogen fixation. Cooperative-extension trials consistently show reduced pea root nodulation when garlic is grown within 2 rows."
    },
    {
      "crop": "Garlic",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Garlic's strong scent confuses carrot fly, the worst pest carrots face. Sulfur volatiles overlap with the carrot rows, masking the carrot scent that the fly tracks."
    },
    {
      "crop": "Garlic",
      "relationship": "Companion",
      "partner": "Cucumbers",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Garlic finishes harvest just as cucumbers need the bed space — perfect rotation. Lingering garlic scent in the soil also suppresses aphids during the cucumber's vulnerable young-vine phase."
    },
    {
      "crop": "Garlic",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Garlic deters aphids on lettuce, and the two crops occupy completely different soil zones (garlic deep, lettuce shallow). Plant lettuce between garlic rows in early spring."
    },
    {
      "crop": "Garlic",
      "relationship": "Companion",
      "partner": "Peppers",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium logic — garlic volatiles deter aphids and thrips on peppers, and the rotation (garlic October-July, peppers June-October) shares one bed across two seasons."
    },
    {
      "crop": "Garlic",
      "relationship": "Companion",
      "partner": "Spinach",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Same logic as the lettuce pairing — garlic's aphid-deterrent effect helps spinach, and the cool-season timing overlaps cleanly."
    },
    {
      "crop": "Garlic",
      "relationship": "Companion",
      "partner": "Tomatoes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Garlic sulfur compounds suppress aphids and spider mites that target tomato foliage. Garlic finishes harvest in early summer, leaving the bed open for the tomatoes to expand."
    },
    {
      "crop": "Lettuce",
      "relationship": "Companion",
      "partner": "Bush beans",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Bush beans fix nitrogen and finish around the same time lettuce slows down for the season. They also draw aphid predators (ladybugs, lacewings) that help lettuce too."
    },
    {
      "crop": "Lettuce",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Carrots and lettuce occupy different soil layers (carrots deep, lettuce shallow) so they share a bed without competing. Both prefer cool weather and similar watering — a classic spring-bed combination."
    },
    {
      "crop": "Lettuce",
      "relationship": "Companion",
      "partner": "Onions",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Strong onion scent helps mask lettuce from aphids; lettuce in turn covers the soil between onion plants, suppressing weeds. Both prefer cool early-season weather."
    },
    {
      "crop": "Lettuce",
      "relationship": "Companion",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Peas finish their cycle just as lettuce hits maturity — and the nitrogen pea roots leave behind feeds the next lettuce sowing. Pea trellises also cast light shade that stalls lettuce bolting."
    },
    {
      "crop": "Lettuce",
      "relationship": "Companion",
      "partner": "Radishes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes break up compacted soil, mature in 25-30 days, and act as a trap crop for flea beetles and leafminers that also target lettuce. Sow them between lettuce rows."
    },
    {
      "crop": "Lettuce",
      "relationship": "Companion",
      "partner": "Spinach",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same cool-season window, same shallow root depth, same pest profile (aphids, leafminers). Interplant rows for a continuous spring salad bed."
    },
    {
      "crop": "Lettuce",
      "relationship": "Companion",
      "partner": "Tomatoes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "In a layered planting, lettuce uses the partial shade of maturing tomato vines to extend its season into early summer. Time the lettuce sowing so heads finish before the tomatoes shade the bed entirely."
    },
    {
      "crop": "Onions",
      "relationship": "Antagonist",
      "partner": "Bush beans",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium-Rhizobium interference as peas — bean root nodulation drops measurably when onions are grown close. Better separated."
    },
    {
      "crop": "Onions",
      "relationship": "Antagonist",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Onions release sulfur compounds (allicin) that disrupt the Rhizobium bacteria peas rely on for nitrogen fixation. Multiple extension sources recommend 2-3 rows of separation."
    },
    {
      "crop": "Onions",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Strong (replicated / peer-reviewed)",
      "reasoning": "The most evidence-backed onion pairing — mixed-row plantings reduce carrot-fly egg-laying by up to 70% (University of Bristol). The two crops cross-mask each other's scent and confuse both carrot fly and onion fly."
    },
    {
      "crop": "Onions",
      "relationship": "Companion",
      "partner": "Cucumbers",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Onion volatiles deter aphids and some cucumber-beetle activity. Plant onions on bed edges so the cucumber vines don't shade them out."
    },
    {
      "crop": "Onions",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Onion scent helps mask lettuce from aphids; lettuce in turn carpets the soil between onion plants and suppresses weeds. Same cool-season planting window."
    },
    {
      "crop": "Onions",
      "relationship": "Companion",
      "partner": "Peppers",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium-aphid-thrip mechanism as tomatoes. Onion tops stay short enough to share a bed with peppers without shading them."
    },
    {
      "crop": "Onions",
      "relationship": "Companion",
      "partner": "Spinach",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Cool-season pairing — onions deter aphids that target spinach, and spinach covers the soil between onion plants."
    },
    {
      "crop": "Onions",
      "relationship": "Companion",
      "partner": "Tomatoes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Onion sulfur volatiles deter aphids and whiteflies that target tomato foliage. Plant onions at the bed edges or between tomato rows — they don't compete for the same root zone."
    },
    {
      "crop": "Peas",
      "relationship": "Antagonist",
      "partner": "Garlic",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium-Rhizobium interference as onions. Garlic's allicin output can stunt pea root nodulation in close plantings."
    },
    {
      "crop": "Peas",
      "relationship": "Antagonist",
      "partner": "Onions",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Alliums release sulfur compounds (allicin) that suppress the Rhizobium bacteria peas rely on for nitrogen fixation. Multiple extension sources recommend at least 2-3 rows of separation between peas and onions."
    },
    {
      "crop": "Peas",
      "relationship": "Antagonist",
      "partner": "Tomatoes",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Peas finish their cycle just as tomatoes ramp up, so they rarely compete in time — but in the overlap, tomatoes shade peas excessively and the humid pea-foliage microclimate can spread powdery mildew to tomato lower leaves."
    },
    {
      "crop": "Peas",
      "relationship": "Companion",
      "partner": "Bush beans",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Same family, same fix-nitrogen biology — they don't fight each other, and the combined planting builds soil nitrogen faster than either alone."
    },
    {
      "crop": "Peas",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Peas fix nitrogen and finish their cycle while carrots are still bulking up; carrot taproots also loosen soil so pea roots establish faster. A classic spring pairing."
    },
    {
      "crop": "Peas",
      "relationship": "Companion",
      "partner": "Cucumbers",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Peas finish their spring cycle just as cucumbers go in. Same trellis, two crops, nitrogen banked for the heavy-feeding cucumbers."
    },
    {
      "crop": "Peas",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same cool-season window, complementary root depths, and peas leave nitrogen behind that the next lettuce sowing pulls up directly."
    },
    {
      "crop": "Peas",
      "relationship": "Companion",
      "partner": "Radishes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes mature in 25-30 days and pull out before peas need the bed space. Their fast germination also marks the slow pea rows."
    },
    {
      "crop": "Peas",
      "relationship": "Companion",
      "partner": "Spinach",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Cool-season pairing where pea trellises cast the light afternoon shade spinach needs to avoid bolting. Spinach also benefits directly from pea nitrogen."
    },
    {
      "crop": "Peppers",
      "relationship": "Antagonist",
      "partner": "Bush beans",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Bush beans tolerate peppers in most cases, but the legumes' nitrogen fixation can over-stimulate pepper foliage at the expense of fruit set if the bed is already moderately fertile. Plant beans on the other side of the garden."
    },
    {
      "crop": "Peppers",
      "relationship": "Antagonist",
      "partner": "Peas",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Pea vines and pepper foliage create a humid microclimate that encourages fungal disease on both crops. The two also fight for water in summer drought stretches."
    },
    {
      "crop": "Peppers",
      "relationship": "Companion",
      "partner": "Basil",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Basil's volatile oils repel thrips and whiteflies that target peppers, while peppers reciprocate by casting light afternoon shade that prevents basil from bolting in midsummer heat. Both prefer the same warm soil and similar watering."
    },
    {
      "crop": "Peppers",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Carrot roots dig deeper than pepper roots, so they share the bed without root competition. Once carrots flower (if a few are left to bolt) they attract hoverflies and parasitoid wasps that hunt aphids on peppers."
    },
    {
      "crop": "Peppers",
      "relationship": "Companion",
      "partner": "Garlic",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium logic as onions, with the bonus that garlic overwinters in the same bed and is harvested mid-summer just as peppers hit their stride. A nice rotation by itself."
    },
    {
      "crop": "Peppers",
      "relationship": "Companion",
      "partner": "Onions",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Allium sulfur volatiles deter aphids and thrips, two of the worst pepper pests. Onion tops also stay short enough that they don't shade peppers as they bulb up."
    },
    {
      "crop": "Peppers",
      "relationship": "Companion",
      "partner": "Spinach",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Spinach finishes its cool-season cycle just as peppers go in, so the timing of the swap works without competition. Spinach also leaves nitrogen-friendly residue."
    },
    {
      "crop": "Peppers",
      "relationship": "Companion",
      "partner": "Tomatoes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same nightshade family with overlapping pest profile — capsaicin in pepper foliage may even suppress some shared pests. The catch: rotate the entire nightshade block every 2-3 years to prevent soil-borne disease build-up."
    },
    {
      "crop": "Radishes",
      "relationship": "Companion",
      "partner": "Bush beans",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Radishes mature before bush beans peak; they also break up soil for the bean root system. No competition because the timing doesn't overlap."
    },
    {
      "crop": "Radishes",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes germinate in 5 days vs. carrots' 14-21 — pulling them out marks the carrot rows and loosens the surface soil so carrot seedlings can push through."
    },
    {
      "crop": "Radishes",
      "relationship": "Companion",
      "partner": "Cucumbers",
      "evidence": "Strong (replicated / peer-reviewed)",
      "reasoning": "Radishes are the most evidence-backed trap crop for cucumber beetles — Cornell Cooperative Extension recommends planting 2-3 radish seeds in each cucumber hill so beetles concentrate on the radish foliage."
    },
    {
      "crop": "Radishes",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes break up compacted soil ahead of delicate lettuce roots, mature out fast, and pull pest pressure (flea beetles) away from lettuce foliage."
    },
    {
      "crop": "Radishes",
      "relationship": "Companion",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes mature in 25-30 days and pull out before peas need the bed space. Fast-rooted radish also marks the slow pea germination rows."
    },
    {
      "crop": "Radishes",
      "relationship": "Companion",
      "partner": "Spinach",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes act as a trap crop for the spinach leafminer — adult flies prefer to lay eggs on radish leaves, and the fast-turnaround radish can be pulled before larvae complete their cycle."
    },
    {
      "crop": "Radishes",
      "relationship": "Companion",
      "partner": "Tomatoes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes finish their 30-day cycle before tomatoes need the space, and the radish roots loosen compacted soil ahead of tomato transplant. A useful succession companion rather than a true intercrop."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Bush beans",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Spinach finishes its cool-season cycle just before bush beans peak — clean succession timing, and bush beans leave nitrogen the next spinach sowing draws on."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Spinach occupies the soil surface, carrots dig deep — no root competition. Both prefer cool early-season weather and similar moisture."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Garlic",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Same allium logic as onions — garlic deters aphids on spinach, and the cool-season timing overlaps cleanly with garlic's spring growth phase."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same cool-season window, same shallow root depth, same pest profile. Interplant rows for a continuous spring salad bed."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Onions",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Onions deter aphids that target spinach; spinach in turn covers the soil between onion plants and suppresses weeds."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Pea trellises cast the light afternoon shade spinach needs to avoid bolting, and the pea root nitrogen directly feeds the spinach planting."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Peppers",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Spinach finishes its cycle just as peppers go in — perfect rotation. Spinach also leaves nitrogen-friendly residue for the heavier-feeding peppers."
    },
    {
      "crop": "Spinach",
      "relationship": "Companion",
      "partner": "Radishes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes act as a trap crop for the spinach leafminer — adult flies preferentially lay eggs on radish leaves. Pull the radishes before larvae complete their cycle."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Antagonist",
      "partner": "Bush beans",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "Bush beans are technically tolerable neighbours, but most extension services recommend keeping legumes a few rows away from tomatoes because the heavy feeding habit of tomatoes can outcompete bean roots for water in dry weeks. Not a hard incompatibility — more a practical spacing issue."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Antagonist",
      "partner": "Peas",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Peas finish their cycle just as tomatoes ramp up, so they rarely compete in time — but in the overlap, tomatoes shade peas excessively and peas can spread powdery mildew that also affects tomatoes. Separate beds is the safer call."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Companion",
      "partner": "Basil",
      "evidence": "Strong (replicated / peer-reviewed)",
      "reasoning": "A 2024 study in Plant Cell Reports identified three basil volatiles (linalool, chavicol, alpha-terpineol) that prime tomato wound-defence genes — caterpillars on primed plants gained roughly half the weight of controls. West Virginia University intercropping trials also recorded ~20% yield gains."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Companion",
      "partner": "Carrots",
      "evidence": "Traditional (limited formal evidence)",
      "reasoning": "A traditional pairing made famous by Louise Riotte. Carrots tolerate the partial shade tomato canopies cast and may loosen soil around tomato roots, but there is no peer-reviewed evidence for a yield benefit either way. Spacing matters more than the pairing."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Companion",
      "partner": "Garlic",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Allium sulfur compounds (allicin) have been shown to suppress aphid populations and spider mites in adjacent crops. Plant garlic 12-18 inches from tomato roots so the alliums do not interfere with the tomato's nitrogen uptake."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Companion",
      "partner": "Lettuce",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Lettuce uses the shaded ground beneath maturing tomato vines, extending the lettuce season into early summer before heat triggers bolting. Lettuce also acts as a living mulch, keeping soil moisture even."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Companion",
      "partner": "Onions",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same allium effect as garlic — strong-scented foliage masks tomato volatiles that aphids and whiteflies use to find their host. Onions are shallow-rooted so they don't compete heavily with tomato roots."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Companion",
      "partner": "Peppers",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Same warm-season window, soil pH, and light demand — they share growing conditions, so a single bed plan works for both. Rotate the whole nightshade group every 2-3 years to limit shared disease pressure."
    },
    {
      "crop": "Tomatoes",
      "relationship": "Companion",
      "partner": "Radishes",
      "evidence": "Moderate (single study / extension)",
      "reasoning": "Radishes mature in 25-30 days — fast enough to harvest before tomatoes need the space. They also break up compacted soil ahead of tomato root expansion."
    }
  ]
}