Check common good-neighbour and keep-apart planting relationships before laying out a vegetable bed.
Companion planting is most useful as a bed-planning aid, not a magic rulebook. Use the checker to identify commonly compatible neighbours and combinations gardeners often prefer to separate.
Relationships are based on common horticultural practice around space, crop-family pressure, competition and garden management. Treat them as layout guidance rather than a guarantee of yield or pest control.
A tomato and basil pairing can be convenient because both suit warm conditions and basil can fit around the edge of a larger tomato planting. That does not mean basil guarantees pest control or a higher tomato yield. The useful part is checking whether the plants can share light, water, root space and management without obvious conflict.
Tomato and basil are often grown together and can fit well in a managed bed, but simply placing them side by side does not guarantee fewer pests or better tomatoes. Sun, airflow, soil fertility, irrigation and spacing still have a larger direct effect on plant performance.
Companion planting advice mixes practical spacing observations, crop-family management, tradition and claims with different levels of evidence. Tiny Mustard Seed treats it as a planning layer rather than a promise that one plant will protect another.
Rotation and disease pressure can matter more than a neighbour list. Two crops may be compatible in space while still creating management problems if they share diseases, compete heavily for light or make harvesting difficult.
Do not rely on that alone. Companion choices can be part of a broader garden plan, but monitoring, hygiene, crop health and appropriate pest management still matter.
Not necessarily. An avoid flag is a prompt to think about competition or management. Real results depend on spacing, soil, climate and how the bed is maintained.