Companion Planting – Plant Compatibility in Shared Cultivation
The deliberate combination of different plant species on a shared growing area – known as companion planting or mixed cropping – is based on the natural biochemical and ecological interactions between crops, herbs, and wild plants. This cultivation practice is historically documented in pre-Columbian cultures of Mesoamerica, where the combination of maize, beans, and squash – known as the "Three Sisters" – was used systematically. The beans fix atmospheric nitrogen, improving soil fertility; the maize provides structural support; the ground-covering squash reduces evaporation and weed pressure. Scientific studies confirm that certain plant combinations produce measurable positive effects: they can reduce pest pressure, promote beneficial insects, improve soil structure, and in some cases increase yields. On the other hand, so-called allelopathic interactions occur when plants inhibit the growth of neighbouring species through root exudates or volatile compounds.
The overview below compiles documented friend and foe combinations and is intended to serve as a practical basis for thoughtful cultivation planning.

Sources & further reading:

• Riotte, L. (1998). Carrots Love Tomatoes: Secrets of Companion Planting for Successful Gardening. Storey Publishing.
• Pfiffner, L. & Luka, H. (2003). Mischkulturen im Gemüsebau – Wirkung auf Schädlinge und Nützlinge. Forschungsinstitut für biologischen Landbau (FiBL), Frick.
• Finckh, M. R. et al. (2015). Perspectives and place of plant diversity in integrated and organic plant protection. Pest Management Science
• Bundeszentrum für Ernährung (BZfE): www.bzfe.de