Gardening

Companion Planting Guide

Find the best plant companions for your garden

Select a plant to see which species grow well together and which should be kept apart. Based on allelopathy research, pest deterrence, and nutrient sharing.

Companion Planting Guide

Select a plant to see its best companions and plants to keep apart.

How to Use

  1. 1
    Select your primary plant

    Choose the vegetable, herb, or flower you want to find companions for from the searchable list.

  2. 2
    Review companions and antagonists

    See which plants benefit your selection (good companions) and which should be planted elsewhere (bad companions).

  3. 3
    Plan your garden layout

    Use the compatibility results to arrange your beds so beneficial neighbors are adjacent and antagonists separated.

About

Companion planting is one of the oldest and most practical strategies in gardening, rooted in the observation that certain plants perform better when grown near specific neighbors. The mechanisms behind these relationships are diverse: some companions repel pests through volatile chemical compounds, others attract beneficial insects that prey on garden pests, legumes fix atmospheric nitrogen that feeds neighboring heavy feeders, and tall plants provide shade or physical support for smaller companions.

The Companion Planting Guide distills this knowledge into a searchable reference. For each plant, it lists proven good companions with an explanation of the benefit (pest deterrence, pollination, nutrient sharing, or physical support) and known bad companions with the reason they should be separated (allelopathic interference, nutrient competition, shared pest attraction, or growth inhibition). The relationships are drawn from a combination of published agricultural research, university extension service recommendations, and well-documented traditional practices. Whether you are laying out a small raised bed of vegetables or designing a large permaculture garden, grouping compatible plants together and separating antagonists is one of the simplest changes you can make to improve yields, reduce pest problems, and build healthier soil without additional inputs.

FAQ

What is companion planting?
Companion planting is the practice of growing certain plants together for mutual benefit. Benefits include pest deterrence (basil repels aphids near tomatoes), pollinator attraction (flowering herbs draw bees to nearby vegetables), nitrogen fixation (legumes enrich soil for heavy feeders), physical support (corn provides a trellis for climbing beans), and shade provision (tall plants shelter heat-sensitive crops). The practice is rooted in centuries of traditional agriculture and increasingly supported by scientific research into plant chemical ecology.
Why should tomatoes and basil be planted together?
Basil is one of the most frequently cited tomato companions because it repels certain insect pests, particularly aphids, whiteflies, and tomato hornworm moths, through volatile compounds released from its leaves. Some gardeners also report that basil improves the flavor of nearby tomatoes, though this is anecdotal. Both plants share similar water and sun requirements, making them easy to co-locate. Basil flowers also attract beneficial pollinators that improve tomato fruit set.
What is allelopathy in plants?
Allelopathy is the process by which a plant releases biochemicals that inhibit the germination or growth of nearby plants. Black walnut trees are the most well-known example: their roots, leaves, and hulls release juglone, which is toxic to tomatoes, peppers, eggplant, and many other species within the root zone. Sunflowers, fennel, and some brassicas also exhibit mild allelopathic effects. The guide flags known allelopathic relationships to prevent planting failures.
Can companion planting replace pesticides?
Companion planting reduces pest pressure but rarely eliminates it entirely. Marigolds repel root-knot nematodes and whiteflies, nasturtiums serve as trap crops for aphids, and strong-scented herbs like rosemary and sage confuse pest insects searching for host plants by scent. However, heavy infestations often require additional integrated pest management strategies. Think of companion planting as the first layer of defense, not a complete replacement for all pest control.
What are the Three Sisters and why do they work?
The Three Sisters -- corn, beans, and squash -- is a companion planting system developed by Indigenous peoples of the Americas. Corn provides a vertical trellis for bean vines to climb. Beans fix atmospheric nitrogen into the soil, feeding the heavy-feeding corn and squash. Squash spreads its large leaves across the ground, shading out weeds and retaining soil moisture. The three species occupy different vertical and horizontal niches, maximizing yield per square foot.