Gardening can be a serene and rewarding hobby, but not all plants are best friends. Some plant combinations can lead to competition for nutrients, stunted growth, or even pest invasions.
To help you cultivate a thriving garden, we’ve compiled a list of plant pairings you should avoid.
1. Tomatoes & Cucumbers
Tomatoes and cucumbers might seem like a match made in salad heaven, but planting them side by side in your garden is a big no-no. While both are part of many summer gardens, they have different nutrient needs and can suffer from overlapping diseases.
Tomatoes are heavy feeders that require ample nutrients, especially calcium. Cucumbers, on the other hand, are susceptible to powdery mildew, a fungal disease that can easily spread to tomatoes.
Both plants can attract aphids and whiteflies, creating a pest haven. Keeping them apart helps ensure each plant gets the care it needs and reduces the risk of shared diseases and pests.
2. Carrots & Dill
Dill can inhibit carrot growth by releasing compounds that can stunt the development of carrot roots. This phenomenon, known as allelopathy, can make it difficult for carrots to thrive when dill is nearby. (ref)
Moreover, dill can attract beneficial insects like wasps and ladybugs that prey on garden pests, which is great for your garden overall but can be overwhelming for delicate carrot seedlings. It’s better to plant dill and carrots in separate areas to give both plants the best chance to flourish.
3. Beans & Garlic
Beans, whether pole or bush varieties, fix nitrogen in the soil, which benefits many plants but not garlic. Garlic, a heavy feeder, competes with beans for nutrients and can inhibit their growth due to its potent natural chemicals.
The strong scent of garlic can also repel beneficial insects that beans attract, such as pollinators. This can lead to lower bean yields. By planting beans and garlic in separate sections of your garden, you allow each to grow without hindrance and maintain a balanced ecosystem.
4. Cabbage & Strawberries
Cabbage and strawberries might sound like an odd couple, and for good reason. These two plants do not get along well in the garden. Cabbage is a member of the brassica family and can release chemicals that stunt the growth of strawberries.
Cabbage attracts pests like cabbage worms and aphids, which can easily spread to nearby strawberries. Strawberries, being low-growing plants, also compete with cabbage for space and nutrients. Planting them separately ensures that each can grow to its full potential without being adversely affected by the other.
5. Onions & Peas
Onions can stunt the growth of peas due to their aggressive root system and high nutrient demands (ref). Peas, which fix nitrogen in the soil, do not benefit from the presence of onions nearby.
The strong odor of onions can also deter pollinators that peas rely on for pod development. Keeping onions and peas in separate parts of your garden helps ensure that both can thrive without interfering with each other’s growth and productivity.
6. Potatoes & Sunflowers
Sunflowers release allelopathic chemicals that can inhibit the growth of potato plants and reduce their yield. Furthermore, sunflowers attract pests such as aphids and beetles that can easily move to potato plants, leading to infestations.
Both plants also compete for sunlight and nutrients, which can lead to stunted growth. Planting sunflowers away from your potato patch helps both plants reach their full potential.
7. Fennel & Almost Everything
Fennel is a notorious loner in the garden. This aromatic herb can release allelopathic chemicals that inhibit the growth of most other plants, making it a poor companion for nearly everything. Fennel can stunt the growth of tomatoes, beans, and many other common garden plants. (ref)
To avoid this issue, it’s best to plant fennel in its own section of the garden, away from other crops. By isolating fennel, you can ensure that its allelopathic properties do not negatively impact your garden’s productivity and health.
8. Corn & Tomatoes
Both plants are heavy feeders and compete for the same nutrients, leading to reduced yields for both. Corn also attracts pests like corn earworms and tomato hornworms, which can devastate both crops.
Additionally, corn’s tall stalks can overshadow tomato plants, depriving them of the sunlight they need for optimal growth. Planting corn and tomatoes in separate areas helps ensure that both plants get the nutrients and sunlight they require to thrive.
9. Asparagus & Garlic
Asparagus and garlic might be culinary companions, but in the garden, they don’t see eye to eye. Garlic can release chemicals that hinder the growth of asparagus, stunting its development. Additionally, both plants are heavy feeders, competing for the same soil nutrients, which can lead to underwhelming growth for both.
Asparagus, a perennial, also requires a stable environment free from root disruption, while garlic’s annual growing cycle can disturb the asparagus bed. Keeping them apart ensures that each plant can grow in optimal conditions without impeding the other’s progress.
10. Peppers & Beans
Peppers are prone to aphids, which beans can attract in large numbers. This can lead to a pest problem that significantly affects both crops.
Furthermore, beans, being nitrogen-fixing plants, can make the soil too rich in nitrogen for peppers, which prefer a balanced nutrient profile. By planting them separately, you reduce the risk of pest infestations and ensure that each plant gets the specific nutrients it needs.
11. Basil & Rue
Basil and rue are two aromatic herbs that should be planted far apart. Rue releases a chemical compound that can inhibit the growth of basil, leading to poor development and reduced yields.
Additionally, rue can attract certain pests, like caterpillars, that can also affect basil plants. By planting these herbs in different areas of your garden, you can ensure that both thrive without negative interactions.
Understanding which plant combinations to avoid is crucial for a thriving garden. By keeping incompatible plants apart, you can prevent nutrient competition, pest invasions, and stunted growth. Remember, a well-planned garden not only looks beautiful but also ensures each plant gets the care it needs to flourish.
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Davin is a jack-of-all-trades but has professional training and experience in various home and garden subjects. He leans on other experts when needed and edits and fact-checks all articles.