Companion Planting
Which plants help each other thrive, which ones compete, and how to build a garden ecosystem where everything works together — naturally reducing pests and boosting yields without chemicals.
Friends & Foes
25 plants — every green tag is a friend, every red tag is something to keep away. Search or filter above to narrow it down.
The Three Sisters
Corn, beans, and squash — one of the oldest and most proven companion planting systems. Developed by Indigenous farmers over thousands of years and exceptionally well-suited to KC's climate.
Fennel Warning: Fennel is strongly allelopathic — it releases chemicals from its roots that inhibit the growth of nearly every vegetable in your garden. Never plant it in your main beds. Grow it in an isolated container or at the far garden edge. It does attract beneficial insects, so keep it nearby — just never integrated. See the Fennel card below for its full incompatibility list.
Why Companion Planting Works
It's not folklore — these are real, measurable mechanisms.
Plants release chemical compounds from their roots that can either stimulate or inhibit neighboring plants. Marigolds release alpha-terthienyl, which is toxic to nematodes for up to 3 years in surrounding soil. Fennel's root exudates inhibit germination and growth of most vegetables — this is why it gets its own container.
Plants broadcast airborne chemical signals that insects navigate by. Aromatic herbs like rosemary, sage, and basil release VOCs that interfere with pest insects' ability to locate their target crops. Aphids literally cannot find the tomato plant they're looking for when basil is growing nearby — the aromatic interference is measurable in the lab.
Some plants are more attractive to pests than others. Nasturtiums draw aphids away from tomatoes and cucumbers — you let the nasturtiums get infested and remove them, along with the pest population. This is a deliberate sacrifice play that's more effective than any spray applied after the fact.
Legumes (beans, peas) host bacteria in root nodules that convert atmospheric nitrogen into a form plants can use. Growing beans alongside heavy feeders like corn and squash effectively fertilizes the bed as you grow. The Three Sisters system leverages this directly — the beans feed the corn and squash throughout the entire season.