Companion planting is an ancient agricultural method in which certain plants are planted next to each other in order to utilize synergistic effects. For cannabis, this means
- Natural plant protection (e.g. against aphids or spider mites)
- Soil improvement through nitrogen fixation or deep loosening
- Biodiversity that stabilizes ecosystems in the grow area
Critical assumptions questioned
Assumption 1: “All companion plants work equally well for cannabis.”
Counterargument: Plants such as mint can be invasive and compete with cannabis for nutrients. Not every combination makes sense.
Assumption 2: “Companion planting completely replaces fertilization.”
Reality: It reduces fertilizer requirements, but high-quality cannabis strains often need additional nutrients.
The 5 best companion plants for cannabis
- Marigolds
- Advantages: Repels nematodes and whiteflies by scent.
- Risk: Can shade cannabis when overplanted.
- Basil
- Advantages: Improves aroma, keeps mosquitoes away.
- Study: In 2018, the University of Naples showed that basil terpenes promote myrcene synthesis in cannabis.
(Continue with chamomile, clover and lavender – in each case with a risk/benefit assessment).
Science vs. tradition – what does research say?
- Evidence: A 2020 study in the Journal of Agricultural Science shows that Tagetes (marigolds) reduces root pests by 62%.
- Limitations: Many claims (e.g. “rosemary increases THC”) are not yet peer-reviewed.
Step-by-step instructions for outdoor grows
- Planning
- Mixed cultivation bed with 70% cannabis, 30% companion plants.
- Monitoring
- Watch out for light competition – cannabis needs at least 6 hours of direct sunlight.
Common mistakes and how to avoid them
- Mistake: Planting herbs such as dill too densely.
- Solution: Keep a distance of at least 30 cm to minimize root competition.