Which plants should not be grown near basil?
Written by
Benjamin Miller
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Planting companions have a significant impact on basil as well as its overall flavor. Some plants release chemicals, while others aggressively compete, causing basil to become stressed. I learned this when my basil was near a well-established sage plant. Always be aware of root interactions and any potential changes to the microclimate when arranging your herb garden.
Chemical Inhibitors
- Rue releases root compounds slowing basil development
- Fennel produces growth-stunting chemicals underground
- Wormwood emits volatile oils affecting leaf flavor
Resource Competitors
- Cucumbers aggressively consume water and nutrients
- Tomatoes create dense shade blocking sunlight
- Zucchini spreads roots suffocating nearby plants
Microclimate Issues
- Sage increases humidity encouraging fungal diseases
- Mint spreads rapidly overwhelming basil roots
- Rosemary alters soil pH making it too alkaline
Roots play a part in underground covert battles. Fennel transmits the chemical anethole to inhibit basil from exploiting nutrients. Rue utilizes alkaloids to affect growth hormones. After losing plants, I now have at least 3 feet of separation. Raised beds with root barriers mitigate issues.
Microclimate precautions to stop fungus issues. Sage may lead to increased humidity around basil, which can cause powdery mildew to develop. Position basil upwind from plants that retain moisture. In my garden plan, basil is grouped with agreeable neighbors (oregano and peppers), creating favorable growing conditions yet not competing with each other.
Soil management mitigates residual effects of bad companions. If soil is amended with compost and plants next to bad species, the soil should still be tested for pH. Aim to adjust the pH to approximately 6.5 if necessary. Ideally, wait at least one season if you want to replant basil back into the soil affected.
Read the full article: How to Grow Basil Successfully at Home
