In the gardening world, the practice of companion planting is as much about avoiding bad neighbors as it is about pairing plants that benefit each other.
Just like people, some plants don’t get along due to various reasons such as differing water, light, and nutrient needs, or because they attract the same pests.
To ensure a thriving garden, it’s important to know which plants to keep apart.
Here’s a detailed look at 14 plants you should never grow side-by-side and the reasons why.
1. Tomatoes and Corn
Tomatoes and corn are attacked by the same pest—the corn earworm, making them poor companions. Growing them together can create a hotspot for infestations, compromising both crops.
2. Beans and Onions
Beans, part of the legume family, are known for their ability to fix nitrogen in the soil. However, they do not fare well when planted near onions or other members of the allium family, such as garlic and leeks.
Alliums can inhibit the growth of beans, likely due to their strong scents or underground chemical interactions.
3. Carrots and Dill
While dill can attract beneficial insects, it’s not a good companion for carrots. Dill can attract carrot root flies, leading to infestations.
Additionally, young dill plants can stunt carrot growth, while mature dill can cross-pollinate with carrots, affecting seed production.
4. Asparagus and Garlic
Garlic and other alliums can stunt the growth of asparagus. Compounds released by garlic and its relatives can inhibit asparagus’s growth, making it less productive and potentially harming the perennial crowns of asparagus.
5. Cucumbers and Aromatic Herbs
Cucumbers are sensitive to the aromatic oils released by certain herbs, such as sage. These strong scents can negatively affect cucumber growth and fruit development.
While some herbs like dill and marigolds are beneficial for cucumbers, it’s best to avoid planting them near sage and other potent herbs.
6. Broccoli and Tomatoes
Both broccoli and tomatoes are heavy feeders, competing fiercely for nutrients. This competition can stunt broccoli’s growth.
Moreover, the solanine produced by tomatoes can be toxic to broccoli, inhibiting its growth and development.
7. Potatoes and Sunflowers
Sunflowers can attract potato beetles, a common pest that targets potatoes.
Additionally, the allelopathic chemicals released by sunflowers can inhibit the growth of potatoes, making this pairing unfavorable for gardeners looking to maximize their potato yield.
8. Strawberries and Cabbage
Strawberries and members of the cabbage family (brassicas) such as kale, broccoli, and cauliflower, should not be planted together.
The brassicas can stunt the growth and fruit production of strawberries due to their large root systems and heavy nutrient demands.
9. Peppers and Fennel
Fennel is known to be allelopathic to most garden plants, meaning it releases compounds that inhibit the growth of nearby plants, including peppers.
Fennel’s strong growth-inhibiting properties make it a poor companion for almost all garden vegetables.
10. Lettuce and Parsley
While not as dramatically incompatible as others on this list, lettuce and parsley can compete for space and nutrients if planted too closely.
Both prefer similar growing conditions, but their close proximity can lead to overcrowding and poor growth outcomes.
11. Peas and Onions
Like beans, peas are negatively affected by the presence of onions and other alliums. The growth of peas can be inhibited by the compounds released by onions, leading to reduced yields.
12. Cauliflower and Strawberries
Cauliflower, another brassica, can have a similar effect on strawberries as cabbage. The heavy nutrient use and large root system of cauliflower can outcompete strawberries, leading to poor fruit development.
13. Radishes and Hyssop
Hyssop, an aromatic herb, can adversely affect the growth of radishes. The exact reason is not well-understood but may involve allelopathic interactions or competition for resources.
14. Kale and Tomatoes
Kale, a nutrient-intensive brassica, does not grow well near tomatoes. The solanine produced by tomatoes can inhibit kale growth, and both plants compete for the same nutrients, often leaving the kale weakened and less productive.
Understanding which plants to keep apart is crucial for maintaining a healthy, productive garden.
By avoiding these incompatible pairings, gardeners can minimize pest issues, reduce competition for nutrients, and ensure that each plant has the best possible conditions for growth.
Companion planting is an art and science, requiring attention to detail and knowledge of plant relationships to create a harmonious garden ecosystem.