Companion planting is an age-old gardening practice that involves growing certain plants together to enhance their growth, improve flavor, or deter pests.
While many plants thrive when grown next to the right companions, some pairings can have the opposite effect, leading to poor growth, reduced yields, or even plant diseases.
Knowing which plants to avoid planting side by side can help you create a healthier, more productive garden. Here are 7 plant pairs that should never be grown together.
1. Tomatoes and Corn
Why They’re Bad Neighbors
Tomatoes and corn are both susceptible to a common pest: the corn earworm (also known as the tomato fruitworm). Planting them together can attract this pest to your garden in droves, leading to significant damage to both crops.
Issues:
- Pest Magnet: Both plants are a favorite of the corn earworm, increasing the likelihood of an infestation.
- Resource Competition: Corn is a heavy feeder, and growing it near tomatoes can lead to competition for nutrients, resulting in reduced yields for both.
2. Onions and Beans
Why They’re Bad Neighbors
Onions release a chemical that can inhibit the growth of beans and other legumes. Beans, in turn, fix nitrogen in the soil, which is beneficial for many plants but can be excessive for onions, which do not require high nitrogen levels.
Issues:
- Growth Inhibition: Onions can stunt the growth of beans, peas, and other legumes.
- Nutrient Imbalance: Beans may make the soil too nitrogen-rich for onions, causing poor bulb development.
3. Cabbage and Strawberries
Why They’re Bad Neighbors
Cabbage and other members of the Brassica family (such as broccoli, cauliflower, and Brussels sprouts) do not grow well near strawberries. The root systems of cabbage plants can release compounds that inhibit the growth of strawberries.
Issues:
- Growth Suppression: Cabbage plants can release chemicals that slow down the growth of strawberries.
- Nutrient Competition: Both plants are heavy feeders and can compete for nutrients, leading to poor yields.
4. Carrots and Dill
Why They’re Bad Neighbors
While both carrots and dill belong to the same plant family (Apiaceae), they don’t make good garden companions. Dill can stunt the growth of carrots, particularly if it matures before the carrots do.
Issues:
- Growth Interference: Dill can inhibit the growth of carrots by releasing chemicals into the soil.
- Cross-Pollination: Dill and carrots can cross-pollinate, resulting in poor-quality seeds and reduced flavor.
5. Cucumbers and Potatoes
Why They’re Bad Neighbors
Cucumbers and potatoes are both susceptible to several common diseases, such as blight. Planting them together can increase the risk of disease transmission and create a challenging environment for both plants to thrive.
Issues:
- Disease Spread: Both cucumbers and potatoes are prone to blight, and planting them together can lead to rapid disease spread.
- Nutrient Competition: Potatoes are heavy feeders, and planting them near cucumbers can lead to competition for essential nutrients.
6. Lettuce and Broccoli
Why They’re Bad Neighbors
Lettuce and broccoli don’t get along well in the garden. Broccoli can release allelopathic chemicals that inhibit the growth of lettuce, leading to smaller, less healthy plants.
Issues:
- Allelopathy: Broccoli’s roots release compounds that can stunt lettuce growth.
- Shade Issues: Broccoli grows tall and can overshadow lettuce, depriving it of the sunlight it needs to thrive.
7. Fennel and Almost Everything
Why It’s a Bad Neighbor
Fennel is one of those plants that doesn’t play well with others. It releases a substance that inhibits the growth of many common garden vegetables, including tomatoes, beans, and most leafy greens.
Issues:
- Growth Inhibition: Fennel releases allelopathic chemicals that can stunt the growth of nearby plants.
- Isolation Needed: Fennel is best planted alone or in a container away from other vegetables.
Not all plants make good neighbors in the garden. By avoiding these poor plant pairings, you can reduce the risk of pests, diseases, and growth problems, ensuring that your garden remains healthy and productive.
Consider planting these “bad neighbors” away from each other and focus on companion planting strategies that promote growth and protect against common gardening challenges.
