Compatibility screen
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Use a sample for a quick screen, or switch to custom when pasting your own bed list.
One crop per line keeps the pair ledger and chart readable. Drop TXT or CSV onto the textarea, or browse for one local file.
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Container mixes get stronger root and water competition cautions than open rows.
Use Tight interplanting when plants will touch canopies or roots before harvest.
Use Separate zones if you can split drip lines, hand-water edges differently, or keep herbs in drier pockets.
Pick the garden problem you most want this screen to catch first.
Conservative mode keeps folklore-style benefits out of the primary signal unless there is a clear layout or plant-association reason.
Higher strictness raises warnings for tight beds, containers, repeated families, and forced water sharing.
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Pair or groupSignalLevelActionConfidenceReasonCopy
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Tags: Education, Gardening
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Companion planting is the practice of placing vegetables, herbs, and flowers near one another because their growth habits can make a bed work better. Useful pairings usually come from practical mechanisms: different root depths, staggered harvest dates, support for climbing crops, flowering plants that feed beneficial insects, light shade for cool-season crops, or a living cover that protects soil.

The idea is helpful, but it is often oversold. Many companion charts present plant pairs as fixed friends or enemies even when the real result depends on spacing, timing, water, cultivar, local pest pressure, and how closely the plants share roots and canopy. A basil plant near tomato is not the same decision in a large in-ground row, a crowded patio planter, and a tight square-foot bed.

Companion planting bed with useful, separate, and water-check relationship lines.

Good planning treats companion planting as a screen, not a verdict. The most useful question is not whether two crops appear together on a chart. It is whether they can share the same soil volume, irrigation pattern, disease plan, sun exposure, and harvest path without making one another harder to grow.

That cautious approach is especially important for small beds. Containers, raised beds, and tight interplanting make root volume, airflow, and water demand matter sooner than a broad row garden. A companion note can still be useful, but it should not override crop rotation, local extension guidance, seed-packet spacing, or direct observation in the bed.

How to Use This Tool:

Use the checker before planting a mixed bed, container, or border so the highest-risk pairings appear before you buy seedlings or set transplants.

  1. Enter one crop, herb, or flower per line in Crops in the bed. Common names and aliases such as bush bean, bell pepper, chili pepper, courgette, rocket, scallion, and zucchini are handled, while duplicate lines are ignored.
  2. Choose Planting context. Container or patio planter raises root-volume and water cautions, while Mixed guild or border is gentler on shade relationships because plants are less likely to be packed into one tight vegetable block.
  3. Set Spacing model. Tight interplanting and Square-foot or intensive bed make close-neighbor cautions stronger than standard row spacing.
  4. Select the Watering pattern. A single shared watering zone makes dry herbs and thirsty crops harder to combine; separate zones or dry edges can reduce that warning.
  5. Pick a Priority lens for the problem you most want to catch first. The pest-support lens gives more attention to flowering and beneficial-insect notes, disease-rotation raises crop-family repeats, and water-airflow favors moisture and shade warnings.
  6. Choose an Evidence stance. Practical grower mode keeps useful traditional notes visible with confidence labels. Conservative evidence mode filters weak helpful claims so practical conflicts lead the result.
  7. Move Close-neighbor strictness from relaxed to strict when the bed is crowded, containers are small, disease has been a recent problem, or the plants will share roots for most of the season.

Start with the summary badge, then read Pair Risk Ledger and Bed Layout Moves. If the crop status mentions an unlisted crop or the ledger says input is needed, fix the crop list or verify the named crop with local guidance before treating the screen as a planting plan.

Interpreting Results:

The strongest warning in the summary should get attention first. Separate first means at least one pair is better moved to another bed, container, or season. Rework layout means the crops may still work if spacing, water, or placement changes. Use spacing care points to a lower-risk watch item. No major flags only means the current screen did not find a listed conflict.

Level What it means Best next check
Separate A strong pair, family, allelopathy, water, or root-volume concern was found. Move one crop, split the crop family into a rotation block, or use a separate container.
Caution The pair can create disease, canopy, spacing, or resource pressure in many home beds. Check the listed action and decide whether wider spacing or a different bed edge solves it.
Watch The concern is real but context-sensitive, often tied to tight spacing or shared watering. Keep the pair only if you can observe growth, prune for airflow, and water each crop correctly.
Useful The pairing has a practical reason to consider it, such as support, flowers, spacing, or harvest fit. Confirm the benefit does not crowd stems, hide pests, or force the wrong water schedule.
Neutral No specific listed signal was found for that pair. Use normal crop spacing, local disease history, and seed-packet guidance.

Pair Risk Ledger is the main audit view because it shows the pair, signal, level, action, confidence, and reason. Bed Layout Moves turns the strongest findings into planting actions, while Evidence Notes explains why family concentration, water demand, shade, flowers, or traditional claims were treated cautiously.

Do not read a low-risk result as proof that a mixed bed will thrive. Unlisted crops are kept neutral, local pests can override broad pair notes, and a relationship map is not a substitute for measuring actual spacing, sun, and irrigation. When the output mentions an unlisted crop, same-family group, or confidence limit, verify that point before planting.

Technical Details:

Companion planting is best treated as a set of overlapping horticultural signals. A pair can be helpful for one reason and still risky for another. Corn, beans, and squash can form a useful support and ground-cover system when timing and water fit. Tomato and basil can be a reasonable nearby harvest pairing. Tomato and potato, however, remain a crop-family disease concern even if another chart lists a nearby herb as helpful.

The checker works from unique crop names after resolving common aliases. Each recognized crop carries a plant family, height class, water preference, root habit, role, and short growing note. Those traits are compared pair by pair, then combined with the selected bed context, spacing model, watering pattern, priority lens, evidence stance, and strictness value.

Rule Core:

The decision logic ranks concrete growing conflicts above weaker companion claims. Higher-severity findings decide the displayed level, while confidence labels keep folklore-style notes separate from practical spacing, family, water, and airflow signals.

Signal Main trigger Result effect Interpretation limit
Specific pair note A listed crop pair has a known useful, caution, or conflict relationship. Adds a named action such as plant nearby, use as an edge plant, separate, or rotate. Some classic pair claims are marked traditional or limited rather than treated as guarantees.
Fennel isolation Fennel appears with another vegetable-bed crop. Raises a strong separate warning for mixed vegetable beds. It is a broad caution; local experience may still justify a separate herb bed or pot.
Same crop family Two recognized crops share a plant family. Raises pest, disease, and rotation cautions, especially for nightshade, brassica, cucurbit, and allium-family groups. Same-family crops can share a bed when spacing is adequate and disease pressure is low, but they should be recorded together.
Water mismatch A low-water crop is paired with a high-water crop. Raises caution more strongly in containers, tight beds, square-foot layouts, and single watering zones. Separate drip lines, hand-watered edges, or a drier herb pocket can reduce the practical problem.
Shade layout care A tall or vining crop is paired with a low crop outside a guild-style context. Warns that sun-side placement, trellising, and pruning matter. Light shade can help some cool-season crops, but unwanted shade can reduce fruiting and airflow.
Root-volume pressure Deep-rooted, tall, or vining crops are placed in containers or intensive spacing. Warns that limited soil volume may matter before any companion benefit appears. Large containers, wider pockets, and trellis lanes can change the severity.
Unlisted crop A crop name is not recognized after alias handling. Keeps that pair neutral unless another recognized signal, such as fennel isolation, applies. Neutral means unknown, not proven compatible.

Level Boundaries:

Levels are ordered by severity. A stronger conflict overrides a weaker useful note so the summary favors planting safety over optimistic pair labels.

Numeric band Displayed level Typical user action
>= 4 Separate Use another bed, container, row block, or season before planting.
3 Caution Rework layout, rotation, water, or spacing before keeping the pair.
2 Watch Keep only with observation, airflow, and water checks.
1 Useful Consider the pairing if it does not create crowding or resource conflict.
0 Neutral Use ordinary crop spacing and local guidance.

Family and Evidence Handling:

Plant family matters because related crops often share pests, pathogens, nutrient patterns, and rotation concerns. The screen treats nightshades, brassicas, cucurbits, and alliums as stronger disease-rotation signals because they often carry practical home-garden consequences.

Family signal Examples recognized here Why it matters
Solanaceae Tomato, pepper, eggplant, potato Nightshade repeats can share blight, wilt, beetle, and rotation concerns.
Brassicaceae Cabbage, broccoli, kale, radish Brassicas can share caterpillar, flea beetle, clubroot, and rotation planning concerns.
Cucurbitaceae Cucumber, squash Vining habit, mildew pressure, and high water demand can dominate spacing decisions.
Amaryllidaceae Garlic, onion, chive Alliums often prefer drier edge management and are treated cautiously with legumes.
Fabaceae Bean, pea Legumes can support soil biology, but they still need spacing and compatible neighbors.
Apiaceae Carrot, dill, fennel, parsley, coriander Some family members flower for beneficial insects, while fennel is handled as a separate caution crop.

The evidence stance changes helpful traditional notes, not hard growing constraints. Conservative mode can turn a traditional helpful note into an optional note, but it still keeps family repeats, water mismatches, shade conflicts, root-volume pressure, and strong separate warnings visible.

Limitations and Privacy Notes:

Companion planting results are planning cautions for home-garden layouts. They are not proof of pest control, yield improvement, disease prevention, or crop safety in a specific yard.

  • The recognized crop set is limited. Unlisted crops are handled cautiously and should be checked with local extension, seed-packet, nursery, or grower notes.
  • The result does not know cultivar resistance, planting date, bed orientation, soil test values, previous disease history, current pest counts, pruning plan, or actual distance between plants.
  • Beneficial-insect and companion claims work best as part of integrated pest management, not as replacements for monitoring, sanitation, barriers, resistant varieties, or label-following pesticide decisions.
  • Crop names and settings are evaluated in the browser session. The checker does not ask for an account, garden address, or uploaded file to produce the result.

When a warning is close to your real garden situation, trust direct observation over the label. Wilt, mildew, aphids, poor fruit set, drying containers, and crowded stems are stronger evidence than a generic pair chart.

Worked Examples:

Tomato, basil, and marigold in a raised bed. With standard spacing, a single shared watering zone, practical grower mode, and standard strictness, the summary can show No major flags. Pair Risk Ledger marks tomato plus basil as Useful, tomato plus marigold as Useful, and basil plus marigold as Neutral. The useful result is not a guarantee of pest control; it means the pair can be reasonable if tomato airflow and harvest access stay open.

Tomato, potato, and pepper under disease-rotation priority. These crops are all nightshades, so the summary can report multiple pairs that should be separated. Pair Risk Ledger shows Separate or strong family warnings, and Bed Layout Moves points toward tracking them as one crop-family block. That is a rotation and disease-planning signal, not a statement that the plants will fail immediately if they are near each other.

Cucumber and sage in a tight patio planter. Set Planting context to container, Spacing model to tight interplanting, Watering pattern to single shared watering zone, and Priority lens to water and airflow. Pair Risk Ledger can raise a Water mismatch to Separate, with the action to split water zones or use a dry edge. A larger planter with separate watering may change the practical decision.

Tatsoi and lettuce as a troubleshooting case. Tatsoi is not in the recognized crop set, so the crop status reports an unlisted item and Pair Risk Ledger keeps the pair neutral with an action to verify local crop guidance. The right response is to confirm tatsoi's brassica-family behavior and spacing needs before treating the neutral result as compatibility.

FAQ:

Does a useful pairing mean pests will be controlled?

No. A Useful row means the pair has a practical reason to consider it, such as flowers, support, spacing, or compatible water needs. It does not replace scouting, barriers, pruning, sanitation, or local pest guidance.

Why did a familiar crop show as unlisted?

The crop name may not match the recognized crop set or aliases. Try a common name such as cabbage, kale, tomato, pepper, bush bean, onion, basil, fennel, or zucchini. If it still shows as unlisted, use the neutral result as a prompt for local guidance rather than as a compatibility decision.

Why does conservative evidence mode hide some helpful notes?

Conservative mode lowers traditional helpful claims when they are not strong enough to lead the result. It still keeps practical conflicts such as same-family concentration, water mismatch, shade, root-volume pressure, and fennel separation visible.

Why do same-family crops get warnings?

Crops in the same plant family can share pests, diseases, and rotation concerns. The warning is strongest for families such as nightshades, brassicas, cucurbits, and alliums, especially when the disease-rotation lens or higher strictness is selected.

Is the crop list sent somewhere for lookup?

The crop list is checked in the browser against the built-in crop and pair information. The page does not need a garden address, account, uploaded file, or remote garden database to produce Pair Risk Ledger, Bed Layout Moves, and Evidence Notes.

Glossary:

Companion planting
Growing crops, herbs, or flowers near one another because a practical relationship may help the bed.
Intercropping
Growing two or more crops in the same space at the same time, often to use space, light, roots, or timing more efficiently.
Crop family
A botanical family such as Solanaceae or Brassicaceae whose members can share pests, diseases, or rotation concerns.
Allelopathy
Plant-produced compounds that can suppress nearby seed germination or growth in some conditions.
Beneficial insects
Pollinators, predators, parasitoids, and other insects that can support garden productivity or pest balance.
Water zone
A part of the bed or container group that can be watered differently from nearby plants.
Root volume
The amount of usable soil or potting mix available for roots, water, nutrients, and stable growth.

References: