Companion Planting Is About Diversity, Not Rules

Companion planting is one of the most shared topics in gardening, and also one of the most oversimplified. Online charts often present tidy lists of “good” and “bad” plant pairings, but they rarely explain why those relationships exist. Without that context, companion planting can feel confusing or overly restrictive.

At its core, companion planting is really about diversity. A garden with a wide range of plants creates resilience, supports beneficial insects, and reduces pest pressure naturally. Incorporating native plants is especially valuable, as they provide food and habitat for pollinators and other beneficial species. This biodiversity matters far more than perfectly pairing every vegetable. Let's look at the nuance left out of some viral companion planting charts and lists.

Beans, Legumes, and Heavy Feeders

One of the most persistent companion planting myths is that beans or other legumes actively share nitrogen with neighboring crops during the same growing season. Legumes do fix atmospheric nitrogen, but that nitrogen is stored within the plant, primarily in its roots. It is not released into the soil in a meaningful way until the plant is cut down and the roots decompose, often the following season.

This means beans are not fertilizing nearby heavy feeders like corn or tomatoes in real time. Their value is long-term soil health, not immediate nutrient sharing. Legumes are best thought of as part of a crop rotation or soil-building strategy rather than a direct companion that boosts neighboring plants.

More Examples

Marigolds are often listed as ideal companions for tomatoes, and this pairing is usually explained as “pest control.” The nuance is that not all marigolds do the same thing, and results vary by species and growing conditions. Some marigolds may help deter certain soil nematodes or confuse insect pests through scent, but they are not a guaranteed solution. In many cases, the benefit of marigolds is simply increased floral diversity, which attracts beneficial insects that help keep pest populations in check.

Many charts suggest planting alliums like onions or garlic near brassicas. This recommendation is based on pest management, not growth enhancement. Strong-smelling alliums can help mask brassicas from pests such as cabbage moths, making it harder for insects to locate the crop. Knowing this allows gardeners to decide whether the strategy makes sense for their space and pest pressure.

Another common example is carrots and tomatoes, frequently shown as ideal companions. In theory, they can grow well together. In practice, many gardeners grow tomatoes during the hottest months of summer and carrots during cooler spring or fall conditions. If they are not in the ground at the same time, the pairing is not especially relevant.

Often called the “Three Sisters,” the combination of Beans, Corn, and Squash is sometimes misunderstood as a perfect, universally applicable system. While it can work well in certain climates and soil types, it relies on specific spacing, timing, and fertility. Corn provides structure, beans climb, and squash shades the soil. Without adequate nutrients, space, and heat, the system can become overcrowded or underperform. The success of this pairing depends heavily on context. Sunflowers swapped for corn can achieve a similar effect, since this trio is really about structure and growth habits.

Break The Rules

“Bad companion” lists are often even less helpful when they do not explain the reason behind the warning. Without understanding whether the issue is nutrient competition, pest attraction, growth habit, or timing, gardeners are left guessing how strictly they should follow the advice, especially in small gardens.

There is no need to memorize lists of good and bad companions. Focus on growing a diverse mix of plants, observing what works in your conditions, and adjusting over time. For gardeners who enjoy having suggestions, we do include a few companion or neighbouring plant ideas on our vegetable seed product pages. They are meant as helpful guidance, not strict rules.