Table of Contents
Use this companion planting chart as a traffic-light guide: plant these together, keep those apart, and treat everything else as a call you make in your own bed. It works best as a starting point, not a rulebook, because soil fertility, sunlight, and spacing decide most of your harvest before any pairing does. The matrix below flags each recommendation by evidence level so you know which combinations are backed by research and which are garden folklore worth testing carefully.
TL;DR:
- The strongest documented companion plantings are beans and squash grown together with corn, forming the traditional Three Sisters system that benefits soil nitrogen and structure.
- Evidence supports pest masking, nitrogen sharing, and beneficial insect attraction as mechanisms behind effective pairings, but proper ratios and timing are critical to success.
- Many popular companion planting recommendations are based on folklore or weak research, so small-scale trials and local conditions should guide choices.
- Container gardens require small, compatible pairings like cherry tomatoes with basil, while large plots benefit from row-based arrangements and crop rotation for disease management.
- Personal experimentation and careful observation over multiple seasons provide more reliable results than relying solely on chart recommendations.
Table of Contents
- Companion Planting Chart for Common Vegetables and Herbs
- How to Turn Chart Data Into Real Planting Decisions
- What the Research Actually Supports (and Where Charts Overreach)
- Best Pairings to Try This Season and What to Avoid
- Layout, Spacing, and Timing That Make Pairings Work
- Why Trust This Chart
- Companion Planting Charts for Containers, Raised Beds, and Large Plots
- A Gardener’s Note on Testing Pairings
- Sources
Companion Planting Chart for Common Vegetables and Herbs
A good companion planting guide tells you not just what to plant together but how confident to be about it. This chart uses three evidence flags: Strong (documented mechanism, well-studied), Moderate (some research support, context-dependent), and Traditional (long-standing garden practice without strong scientific backing). Green means beneficial, red means avoid, and anything not listed is generally neutral.
| Vegetable | Good pairing | Evidence | Avoid | Reason |
|---|---|---|---|---|
| Tomato | Basil, carrots | Moderate | Potato, fennel | Shared blight risk; fennel allelopathy |
| Pepper | Basil, onion | Moderate | Fennel | Growth inhibition |
| Cucumber | Radish, dill | Moderate | Aromatic herbs (sage) | Can stunt cucumber growth |
| Lettuce | Carrots, chives | Traditional | None major | Mild pest confusion effect |
| Carrot | Onion, leeks | Strong | Dill (mature) | Dill can attract carrot pests when flowering |
| Beans/peas | Corn, squash | Strong | Onion, garlic | Alliums can suppress nitrogen-fixing rhizobia |
| Brassicas (cabbage, broccoli) | Dill, nasturtium | Moderate | Strawberries | Competing nutrient needs |
| Onion/garlic | Carrots, tomato | Moderate | Beans, peas | Suppresses legume nitrogen fixation |
| Potato | Beans, corn | Traditional | Tomato, squash | Shared blight and pest pressure |
| Squash | Corn, beans, nasturtium | Strong (Three Sisters) | Potato | Shared pest and disease vulnerability |
The strongest, best-documented row on this whole chart is beans and squash grown alongside corn. Legumes fix nitrogen in the soil through root bacteria, corn provides a natural trellis, and squash’s broad leaves shade out weeds. That’s the Three Sisters system, and it has centuries of Indigenous agricultural practice plus modern soil science behind it.
Herbs and flowers do quiet work most vegetable-only charts miss. Basil, dill, and marigold aren’t companion plants in the nitrogen-fixing sense. Instead, they draw in beneficial insects that hunt aphids and hornworms, which is a more reliable payoff than any specific vegetable pairing on this list.
Here’s a fast cheat sheet for the ten vegetables gardeners grow most:
- Tomato: best with basil and carrots; keep away from potato and fennel.
- Pepper: pairs well with basil and onion; skip fennel nearby.
- Cucumber: likes radish and dill; avoid strong aromatic herbs.
- Lettuce: friendly with almost everything, especially carrots.
- Carrot: thrives near onion; watch mature, flowering dill.
- Beans/peas: love corn and squash; never plant near alliums.
- Brassicas: do well with dill and nasturtium as trap plants.
- Onion/garlic: good with carrots; keep clear of legumes.
- Potato: pairs with beans and corn; separate from tomato.
- Squash: shines in the Three Sisters trio with corn and beans.
How to Turn Chart Data Into Real Planting Decisions
A cell marked “beneficial” on a companion planting chart usually means one of three things is happening, and it helps to know which:
- Pest confusion or masking. Strong-smelling plants like basil or onion can make it harder for pests to locate their target crop by scent.
- Nutrient sharing. Legumes host bacteria that pull nitrogen from the air and deposit it in the soil, feeding nearby heavy feeders like corn or squash.
- Pollinator or predator support. Flowering herbs bring in bees, hoverflies, and parasitic wasps that keep pest populations down.
An “avoid” flag usually points to one of these problems instead: shared pests or diseases (tomato and potato both host blight), allelopathy (fennel releases compounds that stunt neighboring plants), or straight nutrient competition for the same soil resources at the same depth.
Before committing a whole bed to a pairing, run a small trial. Plant one 4×4 test strip with the pairing and a control strip without it, then track germination, pest damage, and yield across a season, a method Illinois Extension recommends for gardeners who want real answers instead of guesses. Keep notes. Repeat it next year before you decide a pairing is worth permanent bed space.
Pro Tip: Ratios matter more than most charts admit. A single marigold in a 10 foot row of tomatoes won’t do much. Trap crops and pest-deterrent herbs need enough density to actually change what insects smell and see.
What the Research Actually Supports (and Where Charts Overreach)
Extension services are consistent on one point: biodiversity and integrated pest management do more for your garden than any specific pairing list. Illinois Extension frames companion planting as a complement to good soil, adequate sunlight, and correct spacing, not a substitute for them. Washington State University Extension goes further, warning that many widely circulated charts blend genuine mechanisms with folklore that never got tested.
The mechanisms that hold up under scrutiny are specific:
- Nitrogen fixation: legumes like beans and peas host root bacteria that enrich soil nitrogen for hungry neighbors.
- Trap cropping: a sacrificial plant draws pests away from your main crop, but only when it’s established early and planted in sufficient proportion to actually pull insects off target.
- Volatile masking: aromatic plants can disrupt a pest’s ability to find its host by smell.
- Allelopathy: some plants release chemical compounds that suppress growth in nearby species. Fennel is the classic offender in vegetable beds.
The limits matter as much as the mechanisms. Density and timing determine almost everything. A review of intercropping studies found real pest-suppression and resilience benefits, but the size of those benefits depended heavily on planting ratios and local conditions, not the pairing alone. Shared-disease risk is another blind spot: tomato and potato, both nightshades, carry the same blight vulnerability, so proximity can amplify risk rather than reduce it regardless of what a chart’s green checkmark suggests.
Plenty of pairings that circulate online, carrots deterring tomato pests, for instance, rest on thin or absent research. That’s exactly why evidence flags matter more than a simple yes or no.
Best Pairings to Try This Season and What to Avoid
Some combinations earn their reputation. Others get repeated because they rhyme, not because they work. Here’s where the evidence actually lands.
Pairings worth trying:
- Tomato + basil: pest confusion effect, moderate evidence, and a kitchen bonus.
- Carrot + onion: onion scent can disrupt carrot fly detection, moderate to strong evidence.
- Corn + beans + squash: nitrogen sharing plus physical support, strong evidence (Three Sisters).
- Cucumber + radish: radish can act as a light trap crop for cucumber beetles.
- Brassicas + nasturtium: nasturtium pulls aphids away from cabbage family crops.
- Lettuce + carrots: different root depths, low competition, traditional but sound logic.
- Squash + nasturtium: added ground cover and pollinator draw.
- Beans + corn: classic nitrogen and structure pairing.
- Tomato + carrots: complementary root depths, low competition.
- Pepper + basil: shared pest deterrence, easy to interplant.
Pairings to avoid:
- Tomato + potato: shared blight risk from the same fungal pathogens.
- Beans/peas + onion or garlic: alliums can suppress the rhizobia bacteria legumes depend on.
- Fennel + almost anything: allelopathic compounds stunt neighboring vegetables.
- Cucumber + sage or other strong aromatics: can inhibit cucumber growth.
- Squash + potato: overlapping pest and disease pressure.
- Brassicas + strawberries: competing nutrient demands in the same soil layer.
- Carrot + mature flowering dill: attracts pests that then move onto the carrots.
- Corn + tomato: both draw the corn earworm, doubling your pest exposure.
Before you commit a bed to any of these, run through three questions: does the pairing solve a problem you actually have (a recurring pest, poor pollination, tight space)? Does the evidence level match how much bed space you’re willing to risk? And do you have room for a control strip to actually measure the result?
Pro Tip: Start your first trial with the Three Sisters or tomato and basil. Both have real mechanisms behind them, so you’re testing execution, not the underlying idea.
Layout, Spacing, and Timing That Make Pairings Work
A companion planting chart tells you what to pair. It won’t tell you how to arrange it, and that’s often where good pairings fail in practice.
- Choose a layout that fits the mechanism. Interplanting (mixing rows) suits pest-masking pairs like basil and tomato. The Three Sisters mound works for nitrogen sharing and physical support. Living mulch, like squash sprawling beneath corn, suppresses weeds and holds soil moisture, but only once the squash canopy is dense enough to close gaps.
- Respect spacing minimums first. Every crop has a baseline spacing need for airflow and root room; check a spacing reference before shrinking rows to fit a companion in. Squeezing companions into space that’s too tight can trigger the exact disease and competition problems companion planting is supposed to prevent.
- Time support plants deliberately. Trap crops need a head start, often planted a week or two before the main crop, so they’re established and attractive by the time pests arrive.
- Log what happens. Note germination dates, first pest sighting, and yield at harvest. West Virginia University Extension recommends treating this as an ongoing local experiment, not a one-season verdict.
Rotate crop families each year regardless of which pairings worked, since soil-borne pests and diseases build up in the same spot over time. A layout guide built around rotation makes this easier to track from one season to the next.
Why Trust This Chart
This chart was built by cross-referencing land-grant extension publications and peer-reviewed intercropping research, then flagging each pairing by how strong that evidence actually is rather than how often it’s repeated online. Evidence flags favor documented mechanisms over tradition alone. If you’ve trialed a pairing in your own garden with different results, we want to hear about it. Local soil, climate, and pest pressure change outcomes more than any chart can predict.
Companion Planting Charts for Containers, Raised Beds, and Large Plots
A chart built for a quarter-acre plot doesn’t transfer cleanly to a patio container, and that mismatch causes more disappointment than any pairing itself.
Container gardens need compact, low-competition pairings since root space is the limiting factor, not pest pressure. Cherry tomato with a single basil plant works in a 5 gallon container. Skip anything sprawling, like squash paired with corn, since containers can’t support the root spread the Three Sisters system needs.
Raised beds are the sweet spot for most chart recommendations on this page. A standard 4×4 or 4×8 bed gives enough room for real density: a corn, bean, and squash trio, or a tomato and basil border with carrots tucked along the edge. This is also the ideal scale for the trial method described earlier, since one bed can hold both a test strip and a control strip.
Large plots shift the strategy toward whole-row companion planting rather than plant-by-plant pairing. Instead of interplanting basil between individual tomato plants, you’d run alternating rows of tomatoes and a flowering insectary strip (dill, marigold, alyssum) every few rows to pull in beneficial insects across the whole field, not just one bed. Trap cropping also scales better here, since large plots can dedicate a full border row to sacrificial plants without sacrificing much total yield.
Whatever the scale, the underlying rule from every extension source on this topic stays the same: match plant density and spacing to the space you actually have, then layer companion strategies on top.
A Gardener’s Note on Testing Pairings
I run every new pairing in one small bed first, never across the whole plot, and I keep a simple notebook rather than trusting memory. Two seasons of basil next to tomatoes told me more than any chart could, mostly because I could see exactly which pests showed up and when. Charts get you started. Your own dirt, your own pests, and two seasons of paying attention get you the real answer. If you’ve tried a pairing here and gotten a different result, tell us about your soil and your region. That’s the data this chart is missing.
— Povilas
Sources
- Companion planting: Combining plants for a healthy, well-balanced garden | Illinois Extension
- Herbs make good plant partners and companions | Penn State Extension
- Intercropping and biodiversity benefits (PMC review)
- Trap cropping guidance | University of Missouri IPM
Check with your local extension office for advice specific to your climate and soil, since pest pressure and growing seasons vary widely by region.
Want a broader foundation before you start experimenting with pairings? Lushygardens’ beginner gardening guide covers the soil, sunlight, and spacing fundamentals that make any companion planting chart actually pay off.
Recommended
- What Garden Plants Grow Well Together: Home Gardener’s Guide
- Companion Planting Guide: Simple Tips for Healthy Gardens
- A Successful Garden Partnership Means a Better Harvest: What Should You Plant Next to Carrots?
- What is Companion Planting? Understanding Its Benefits
I’m Eleanor, a seasoned gardener with over three decades of experience tending to Mother Nature’s creations. Through Lushy Gardens, I aim to share my wealth of knowledge and help fellow plant enthusiasts uncover the wonders of gardening. Let’s dive into this journey together, one leaf at a time.
