GardenPairs - Companion Planting & Planting Calendars

Type "tomato companion plants" into a search engine and you will get a dozen chip-shaped charts that all disagree with each other, none of which explain why a pairing supposedly works, and most of which blend a real, tested mechanism together with a garden myth as if the two carried the same weight. That mismatch is the entire reason GardenPairs exists: a companion-planting reference that tells you which pairings are backed by real evidence, which ones are traditional lore passed down without a controlled trial behind them, and which sit somewhere in between - on every single pairing, not just the famous ones.

Companion Planting Without the Guesswork

Every pairing on this site names the actual mechanism first: nitrogen fixed into the soil by a legume's root nodules, a strong-scented herb masking the smell a pest hunts by, a sacrificial trap crop pulling aphids away from the plant you actually want to protect, two root systems working different soil depths so they are not competing for the same water and nutrients. "They're good companions" is not an answer on this site - the mechanism is the answer, and the pairing page tells you what to watch for so you can judge the result in your own bed instead of taking our word for it.

Evidence vs. Lore, Labelled Honestly

Some companion-planting claims have been tested - marigold suppressing certain root-knot nematode species is a good example, and it has real trial support. Others, like basil supposedly improving a tomato's flavor by growing nearby, are traditional garden lore with no controlled evidence behind them, even though they are repeated as fact on almost every companion-planting chart online. We label every pairing evidence-backed, traditional lore, or mixed, and we say plainly why - see the Methodology page for how that rating is decided and dated.

Built Around USDA Zones, Not Guesses

A planting calendar that ignores your climate zone is a coin flip. Every zone guide on GardenPairs states the average annual extreme minimum temperature that defines the zone, the typical frost window it implies, and a month-by-month planting rhythm you can actually follow - dated and sourced on the Methodology page, and reviewed on an annual refresh cadence because frost data drifts and USDA zone maps are periodically revised.

Why GardenPairs

We built this because the free companion-planting web is dominated by chip-style charts copied from site to site, each one a little different, none of them citing anything, and almost none distinguishing a tested agronomic mechanism from a folk saying. A new gardener has no way to tell which claim to trust. GardenPairs treats that distinction as the whole point: real growing guides for the crops themselves, pairing pages that explain the actual interaction instead of a bare verdict, zone-based timing instead of a generic "plant in spring," and free tools that read the same underlying data as the pages so a tool result and a written page can never quietly disagree with each other.

• Crop guides covering real cultivation needs, spacing, and each crop's confirmed companions and antagonists
• Companion-pair pages naming the mechanism and rating the evidence, not just a beneficial/antagonist verdict
• Zone-aware When to Plant pages for sowing and transplant timing
• USDA zone guides with frost windows and a month-by-month calendar
• Garden bed layout guides - square-foot, raised-bed, container, vertical, three sisters and more
• Four free, client-side tools: a companion pairing checker, a planting calendar generator, a bed layout helper, and a frost-date lookup

How to Use This Site

If you already know what you want to grow, start with that crop's growing guide and follow the companion links from there. If you are planning a whole bed from scratch, start with your USDA zone to get a realistic planting window, then use the Bed Layout Helper to lay crops out in a way that respects the companion-planting relationships between them. If you already have two specific crops in mind and just want a quick answer, the Companion Pairing Checker above will tell you in one click whether we have a documented relationship between them.