🌿 Plant Companion Calculator
Discover the best companion plants for your garden. See which crops grow well together, which pairings to avoid, and how to combine plants for healthier soil, fewer pests, and bigger harvests.
🔧 Analyze Your Garden Companions
What is a Plant Companion Calculator?
A plant companion calculator helps you design healthier, more productive garden beds by mapping out which crops support one another and which ones compete or attract trouble. Companion planting is an old gardening practice rooted in observation: certain plant pairings repel pests, enrich the soil, attract pollinators, or simply make better use of the same patch of ground.
Instead of memorizing long compatibility charts, you choose a main crop and check off the plants already growing in your garden. The tool sorts each pairing into excellent, neutral, or best-avoided categories and gives you an overall compatibility score, so you can see at a glance whether your bed is set up for success.
Whether you are planning a small raised bed or laying out a full backyard plot, thoughtful companion planting can cut down on pest problems, reduce the need for fertilizers and sprays, and help every plant reach its potential. Use the suggestions as a flexible framework and refine your combinations each season based on what thrives in your climate and soil.
📖 How to Use the Companion Calculator
1Choose Your Main Crop
Begin by selecting the central plant you are building the bed around — perhaps tomatoes, beans, or a leafy green like lettuce. This is the crop whose companions and antagonists the calculator will analyze, so pick the one you most want to protect and maximize.
If you grow several headline crops, run the calculator once for each. Plants that are an excellent companion for one main crop can be a poor neighbor for another, so analyzing each in turn gives you a clearer picture of the whole bed.
2Check Off What You Are Growing
Tick every plant you already have or plan to include nearby, from vegetables to herbs and flowers like basil, marigolds, and nasturtiums. The more accurately you reflect your real bed, the more useful the analysis becomes.
Do not worry about getting it perfect on the first pass — you can add or remove plants and re-run the analysis as your garden plan evolves over the season.
3Review Your Compatibility Score
The calculator returns a compatibility score from 0 to 100 along with counts of excellent, neutral, and avoid pairings. A green score (70+) signals a well-matched bed, amber (40–69) means it works but could be improved, and red (below 40) flags combinations worth rethinking.
Use the score as a quick health check while you experiment with different plant groupings before you commit seeds and transplants to the ground.
4Act on the Suggestions
Below the score you will see lists of excellent companions, plants to avoid, and suggested additions that would strengthen the bed. Swapping out a problem pairing or adding a recommended companion is often enough to lift a marginal layout into a thriving one.
Pay special attention to the suggested additions: these are beneficial plants drawn from your main crop's proven companions that you have not yet included.
💡 Companion Planting Tips
- Mind the shade: Place tall crops like corn on the north side of a bed so they do not shade lower-growing neighbors.
- Feed with legumes: Beans and peas fix nitrogen in the soil, making them valuable neighbors for hungry leafy and fruiting crops.
- Plant flowers on purpose: Marigolds and nasturtiums draw in beneficial insects and lure pests away from your vegetables.
- Interplant for space: Tuck quick crops like radishes between slower ones to harvest more from the same square footage.
- Rotate each year: Move plant families to a new bed annually to keep soil balanced and break pest and disease cycles.
🎯 Benefits of Companion Planting
🐞 Natural Pest Control
Aromatic herbs and bright flowers confuse, repel, or trap insect pests, letting you protect crops without reaching for chemical sprays. Marigolds discourage soil nematodes while nasturtiums pull aphids away from prized vegetables.
🌾 Healthier Soil
Nitrogen-fixing legumes such as beans and peas enrich the soil for the plants around them, while deep-rooted crops break up compaction. Pairing heavy and light feeders keeps nutrients in balance across the whole bed.
🦋 Better Pollination
Flowering companions draw bees, hoverflies, and other pollinators into your garden, improving fruit set on tomatoes, squash, cucumbers, and beans. More visitors mean fuller, more reliable harvests.
📐 Smarter Use of Space
Interplanting fast and slow crops, and tall and low growers, lets you harvest far more from a small bed. Quick radishes mature before slower neighbors need the room, doubling up on the same ground.
💧 Moisture & Weed Control
Sprawling crops like squash shade the soil, locking in moisture and crowding out weeds. Living ground cover means less watering and far less time spent weeding through the season.
🌍 A More Resilient Garden
Diverse, well-matched plantings are less vulnerable to a single pest or disease wiping out a crop. Companion planting builds a small ecosystem that supports itself and bounces back from setbacks.
❓ Frequently Asked Questions
What is companion planting?
Companion planting is the practice of growing certain plants close together because they benefit one another. Some combinations improve pest resistance, others enrich the soil, attract pollinators, or make better use of limited bed space. Gardeners have relied on these pairings for generations, and modern growers use them to reduce reliance on chemical sprays while boosting overall garden health and yields.
What are the Three Sisters, and why do they work together?
The Three Sisters are corn, beans, and squash, a planting trio used by Indigenous North American growers for centuries. The corn provides a tall stalk for the beans to climb, the beans fix nitrogen in the soil to feed all three plants, and the broad squash leaves shade the ground to suppress weeds and retain moisture. Grown together they form a mutually supporting community that needs little extra fertilizer or weeding.
How does companion planting deter pests naturally?
Many companion plants confuse or repel insect pests through strong scents or by masking the smell of a vulnerable crop. Aromatic herbs such as basil and rosemary, and flowers like marigolds and nasturtiums, are classic examples. Marigolds help discourage root-knot nematodes, while nasturtiums act as a trap crop that lures aphids away from your vegetables. Mixing these plants among your beds reduces pest pressure without sprays.
Which plants should I avoid growing next to each other?
Some plants compete for the same nutrients, release growth-inhibiting compounds, or attract shared pests, so they grow poorly together. For example, fennel inhibits many vegetables and is best kept apart, while onions and garlic can stunt beans and peas. Tomatoes and brassicas (cabbage, broccoli, kale) also tend to compete heavily. The calculator above flags these problem pairings so you can plan your beds around them.
How is the compatibility score calculated?
The score reflects how well your selected garden plants pair with your chosen main plant. Each garden plant is sorted into excellent, neutral, or avoid based on established companion relationships, then the result is converted to a 0–100 percentage. Scores of 70 or higher indicate a strongly compatible bed, 40–69 suggests a workable mix with room to improve, and below 40 means you may want to rethink some pairings.
Does companion planting actually improve yields?
When used thoughtfully, companion planting can improve yields by reducing pest damage, improving pollination, and making fuller use of space and soil nutrients. Nitrogen-fixing legumes feed heavy feeders nearby, flowering companions draw in pollinators, and interplanting fast crops like radishes between slower ones increases harvest from the same area. Results vary by climate and soil, so treat the suggestions as a starting framework you refine each season.
How do I plan a garden bed using companion plants?
Start with your main crop, then add companions that support it and remove any known antagonists. Place taller plants on the north side so they do not shade shorter ones, leave space for airflow to limit disease, and tuck pest-repelling herbs and flowers along the edges. Rotate plant families to different beds each year to keep the soil balanced and break pest and disease cycles.