Friends or Foes? Garden Companions to Avoid

Planting the wrong vegetables or herbs together can be a recipe for disaster in your garden. These incompatible pairings can lead to weak and stunted plants, attract unwanted pests, and even alter the taste of your produce.

By Ryan Dorn, SouthernSeeds.com

Gardening is often described as a peaceful pastime, a dance with nature where harmony reigns. But beneath the surface of this tranquil image lies a hidden world of plant rivalries, secret alliances, and even outright warfare. Yes, your garden is a battleground, and the stakes are high: a bountiful harvest or a season of disappointment.

The truth is, not all plants play well together. Some combinations, seemingly innocent at first glance, can lead to a domino effect of pest infestations, rampant diseases, and stunted growth. It's a botanical soap opera you don't want to star in.

So, before you unleash chaos in your garden beds, take a moment to learn from the wisdom of seasoned gardeners and the secrets of plant compatibility. In this post, we'll uncover some surprising plant pairings that, despite their individual merits, should never share the same soil. From the classic tomato and potato feud to the lesser-known animosity between fennel and cilantro, we'll reveal the plant combinations that could sabotage your gardening success. Consider this your guide to preventing garden drama and ensuring a harmonious harvest.

A Comprehensive Guide to Incompatible Plant Pairings

Below, you'll find a comprehensive list of plant pairings to avoid. While it may seem extensive, we wanted to create a valuable resource you can reference throughout your gardening journey. We've covered a wide range of common vegetables and culinary herbs, ensuring you have the information you need to make informed decisions and cultivate a thriving garden.

Asparagus

Asparagus should not be planted near members of the allium family, such as garlic, onions, and shallots, as these can stunt its growth. Additionally, avoid planting asparagus near potatoes, as they compete for similar resources and can increase the risk of disease spread.

Basil

Basil should not be planted near rue or sage. Rue can inhibit basil's growth, and sage can compete for similar resources, leading to less vigorous plants.

Beans

Beans are notoriously finicky about their companions. While bush beans and beets can coexist peacefully, avoid planting climbing beans near beets, as the beans will overshadow them and compete for sunlight. Additionally, beets prefer slightly acidic soil, while beans thrive in neutral to slightly alkaline soil. Members of the allium family, such as chives, fennel, garlic, and onions, should be kept away from beans, especially broad beans, as they release chemicals that can inhibit bean growth. Sunflowers, with their towering stature, are also poor companions for climbing beans, as they compete for vertical space and sunlight.

Beets

Beets can be grown alongside a variety of plants without issue. However, they should be kept away from pole beans, as the beans' vining growth can overshadow and stunt the beets. Additionally, avoid planting beets near mustard greens, as these can attract pests that damage beets.

Berries

Berries, while a delicious and nutritious addition to any garden, can be sensitive to certain companions. Avoid planting berries near nightshades (tomatoes, peppers, eggplants), as these can harbor diseases like verticillium wilt and blight that can spread to your berry patch. Brassicas (cabbage, broccoli, cauliflower) are also not ideal companions for berries, as they attract pests like cabbage worms and aphids that can damage berry plants. Melons and cucumbers should be kept at a distance, as they can compete for resources and create a humid environment that may encourage fungal diseases in berries. Lastly, while rarer to see, keep berries well away from black walnut trees, which release a chemical called juglone that is toxic to many plants, including berries.

Broccoli

Broccoli, a member of the Brassica family, prefers its own company in the garden. Avoid planting it near other brassicas like cauliflower, cabbage, or kale, as they can compete for similar resources and attract the same pests and diseases. Dill is another plant to avoid, as it can inhibit broccoli growth. Additionally, strawberries should be kept away from broccoli, as they can attract pests that may also damage broccoli plants. While not a direct conflict, planting broccoli near tall plants like corn or sunflowers can lead to shading, which can hinder broccoli's growth.

Brussels Sprouts

Brussels sprouts, like their Brassica relatives, prefer to keep their distance from certain plants in the garden. Avoid planting them near other brassicas, such as broccoli, cauliflower, cabbage, and kale, as they share susceptibility to similar pests and diseases, and can compete for resources. Additionally, keep Brussels sprouts away from strawberries. Strawberries can attract pests that may also feed on Brussels sprouts, and they can compete for similar nutrients in the soil.

Cabbages

Cabbages should not be planted near strawberries or other brassicas like broccoli or cauliflower. Strawberries and brassicas compete for similar resources, and close proximity can increase the risk of pest and disease transmission.

Carrots

Carrots can be a bit picky about their companions. While they enjoy the company of many plants, it's best to avoid planting them near dill, parsnips, or potatoes. Dill can inhibit the growth of carrots and attract pests that feed on their foliage. Parsnips, being close relatives to carrots, can attract the same pests and diseases, increasing the likelihood of problems for both crops. Additionally, potatoes can harbor pests and diseases that can also infect carrots, so it's wise to keep them separated in the garden.

Cauliflower

Cauliflower, like its fellow brassicas, prefers to keep its distance from certain plants in the garden. Avoid planting it near other brassicas, such as broccoli, cabbage, brussels sprouts, and kale, as they share susceptibility to similar pests and diseases, and can compete for resources. Additionally, keep cauliflower away from strawberries and grapes. Strawberries can attract pests that may also feed on cauliflower, and while rare to see near each other, grapes can compete for resources that can hinder cauliflower's growth.

Celery

Celery, while a versatile and delicious addition to any garden, has a few foes it would prefer to avoid. Primarily, it should be kept away from corn, as this towering crop is a notoriously hungry feeder and will quickly deplete the soil of nutrients that celery needs to thrive. Additionally, corn's tall stalks can shade out celery, depriving it of essential sunlight. Celery also doesn't fare well when planted near potatoes. Both plants have shallow root systems that can compete for space and resources, and potatoes can harbor pests and diseases that can spread to celery, such as blight and leafhoppers. Lastly, avoid planting celery near members of the Aster family, like sunflowers and marigolds.

Chives

Chives, like other members of the allium family, release a chemical called juglone, which can inhibit the growth of some plants, including peas and beans. While a small amount of juglone might not be detrimental, planting chives in close proximity to these legumes can lead to stunted growth and reduced yields.

Cilantro (Coriander)

Cilantro and coriander are generally easygoing companions, but it's best to avoid planting them near fennel. Fennel releases compounds that can inhibit the growth of cilantro and coriander, leading to stunted plants and reduced flavor.

Corn

Corn, due to its size and voracious appetite for nutrients, should not be planted near celery or other heavy feeders like potatoes or tomatoes. These plants will compete for resources, leading to stunted growth and reduced yields for both corn and its companions. Additionally, avoid planting corn near sunflowers. Both plants are tall and can shade each other out, reducing sunlight exposure and hindering their growth.

Cucumber

Cucumbers, with their sprawling vines and thirst for sunshine, are not always the most amicable garden companions. They should be kept away from aromatic herbs like sage, as these can inhibit their growth. Additionally, potatoes should not be planted near cucumbers, as they can compete for resources and increase the risk of disease spread. 

Dill

Dill, while a beneficial herb for attracting pollinators and repelling certain pests, should not be planted near carrots. Dill can release compounds that inhibit carrot growth, leading to stunted or misshapen roots. Additionally, dill can attract carrot flies, which can damage both dill and carrot plants. It's best to keep these two plants separated in the garden.

Eggplants

Eggplants, being members of the nightshade family, should not be planted near other nightshades like tomatoes and potatoes. This is because they share susceptibility to similar pests and diseases, such as blight and verticillium wilt. Additionally, avoid planting eggplants near fennel, as fennel can inhibit their growth.

Fennel

Fennel is a bit of a lone wolf in the garden, and it's best to give it some space from most other plants. It releases compounds that can inhibit the growth of many vegetables and herbs, including beans, tomatoes, peppers, and cilantro. It's also not a good companion for kohlrabi or caraway. To prevent fennel from negatively impacting the growth of other plants, it's best to plant it in its own dedicated space or in a container.

Garlic

Garlic, with its pungent aroma and pest-repelling properties, is a valuable asset in the garden. However, it can inhibit the growth of certain plants, particularly legumes like peas and beans. Additionally, garlic should not be planted near asparagus or members of the Brassica family, such as cabbage, broccoli, and cauliflower, as it can stunt their growth.

Kale

Kale, a hardy and nutritious leafy green, is generally a good neighbor in the garden. However, it's best to avoid planting it near strawberries or pole beans. Strawberries can attract pests that may also feed on kale, such as aphids and spider mites. Pole beans, with their vining growth habit, can overshadow kale and compete for sunlight, hindering its growth.

Lavender

Lavender, with its fragrant blooms and drought tolerance, is a popular addition to gardens. However, it's best to avoid planting it near overly thirsty plants like melons or cucumbers. These plants have high water requirements that can create a humid environment that lavender dislikes. Additionally, lavender prefers slightly alkaline soil, while melons and cucumbers thrive in slightly acidic soil, making them incompatible companions.

Leeks

Leeks, like other alliums, don't play well with beans and peas. The chemical compounds in leeks can inhibit the growth of these legumes, leading to stunted plants and reduced yields. It's best to keep a good distance between these two types of plants to ensure both can thrive.

Lettuce

Lettuce, while a refreshing and versatile salad staple, can be a bit sensitive when it comes to its neighbors in the garden. It's best to avoid planting lettuce near members of the brassica family, such as broccoli, cabbage, and cauliflower. These plants release compounds that can inhibit lettuce seed germination and stunt the growth of young seedlings. Additionally, fennel should be kept far away from lettuce, as it secretes a chemical that can significantly stunt lettuce growth. Parsley is another herb to avoid planting near lettuce, as it can cause lettuce to bolt prematurely, leading to bitter-tasting leaves.

Melons

Melons, while delicious and refreshing, can be a bit finicky when it comes to their neighbors. Avoid planting them near potatoes, as potatoes can harbor pests and diseases that can spread to melons. Additionally, it's best to avoid planting melons too close to other cucurbits, like cucumbers and squash. While they can technically be grown together, close proximity can increase the risk of pest and disease pressure.

Mints 

Mints, while refreshing and versatile, are vigorous growers and can easily become invasive in the garden. Its spreading roots can quickly choke out neighboring plants, competing for space and resources. Therefore, it's best to plant mint in containers or in areas where you can control its spread. If you choose to plant mint in the ground, consider using a physical barrier, such as a buried container or edging, to prevent it from taking over your garden.

Mustards

Mustards, while generally easy to grow and beneficial for pest control, should not be planted near beets. Mustards can attract pests like flea beetles, which can also damage beets. Additionally, mustards can inhibit the growth of other members of the Brassica family, such as cabbage, broccoli, and cauliflower.

Okra

Okra, a Southern staple known for its edible pods, is a relatively low-maintenance plant that thrives in warm climates. However, it's best to avoid planting okra near potatoes. Potatoes can harbor pests and diseases that can also infect okra, such as nematodes and verticillium wilt. Additionally, potatoes are heavy feeders and may compete with okra for nutrients, leading to less vigorous growth for both plants.
 

Onions

Onions, while a staple in many dishes and a natural pest repellent, can be surprisingly picky about their garden companions. Avoid planting onions near beans and peas, as the sulfur compounds released by onions can stunt the growth of these legumes. Additionally, keep onions away from sage, as this herb can also hinder their development.

While onions generally get along well with other members of the allium family (like garlic and chives), it's best to give them some space. Planting them too close together can increase the risk of pest and disease spread, as they share susceptibility to similar problems.

Oregano

Oregano is generally a beneficial companion plant, enhancing the growth and flavor of many vegetables, particularly those in the nightshade family like tomatoes and peppers. However, it's best to avoid planting oregano near cucumbers. While they don't directly harm each other, oregano can sometimes become too vigorous and outcompete cucumbers for space and resources.

Parsley

Parsley is a versatile herb that can be planted near many vegetables and herbs without issue. However, it's best to avoid planting parsley near lettuce. Both plants have similar growth habits and can compete for resources, leading to weaker plants and reduced yields. Additionally, lettuce can attract pests that may also damage parsley. To ensure both plants thrive, give them some space in the garden or consider planting them in separate containers.

Parsnips

Parsnips, with their long growing season and specific needs, are best kept away from certain garden companions. As members of the carrot family, parsnips should not be planted near carrots or dill, as they can attract the same pests and diseases, including carrot rust flies and leafhoppers. Additionally, avoid planting parsnips near celery, as these two plants can compete for resources and hinder each other's growth.

Peas

Peas are generally friendly and beneficial companions in the garden, fixing nitrogen in the soil and attracting pollinators. However, they should not be planted near members of the allium family, such as onions, garlic, and shallots. These plants release compounds that can inhibit the growth of peas, leading to stunted plants and reduced yields. Additionally, avoid planting peas near gladiolus, as these flowers can attract pests that also damage peas.

Peppers

Peppers, while versatile and flavorful, can be a bit picky about their companions. Avoid planting them near fennel, as fennel releases compounds that can inhibit their growth. Additionally, keep peppers away from members of the Brassica family, such as cabbage, broccoli, and cauliflower. These plants have different growing requirements and can attract pests that may also target peppers. While apricot trees are not directly harmful to peppers, they can attract pests that may damage pepper plants, so it's best to plant them at a distance.

Potatoes

Potatoes, being members of the nightshade family, should not be planted near other nightshades like tomatoes, peppers, or eggplants. This proximity increases the risk of spreading diseases like blight and verticillium wilt. Additionally, avoid planting potatoes near members of the Cucurbit family, such as cucumbers, squash, and pumpkins, as these can attract pests that also damage potatoes. Sunflowers, while often thought to be beneficial companions, can actually stunt the growth of potatoes and should be planted elsewhere.

Pumpkins

Pumpkins, being members of the Cucurbit family, should not be planted near other cucurbits like squash, cucumbers, or melons. This close proximity can increase the risk of pest and disease spread, particularly squash vine borers and powdery mildew. Additionally, avoid planting pumpkins near potatoes, as these can also harbor pests and diseases that affect cucurbits. Keep in mind that pumpkins can cross-pollinate with other members of the squash family, so if you're saving seeds, it's best to isolate different varieties. However, if you're simply growing pumpkins for their fruit, cross-pollination won't affect the current harvest.

Radish

Radishes are generally easygoing companions in the garden and can be planted near many vegetables and herbs. However, it's best to avoid planting them near hyssop. Hyssop is believed to inhibit the growth of radishes, leading to smaller, less flavorful roots.

Rosemary

Rosemary, with its strong aroma and specific growing preferences, can be a bit picky about its neighbors. Avoid planting it near potatoes, as they have different watering needs and rosemary can compete with potatoes for nutrients. Additionally, keep rosemary away from carrots, as the two plants have incompatible root systems and can hinder each other's growth.

Sage

Sage, with its aromatic foliage and culinary versatility, may seem like a friendly addition to any garden. However, it can be a bit of a bully to certain plants. Avoid planting sage near cucumbers, as it can inhibit their growth and reduce their yield. Brassicas, such as broccoli, cauliflower, and cabbage, should also be kept away from sage, as they have different watering needs and may not thrive in the same conditions.

Savory

Savory, a member of the mint family, is generally a friendly and beneficial companion in the garden. It can be planted near most vegetables and herbs without issue. However, it's best to avoid planting savory near beans. Savory can inhibit the growth of beans, leading to stunted plants and reduced yields.

Spinach

Spinach, a cool-season green known for its nutritional value, can be a bit particular about its garden neighbors. Avoid planting it near strawberries, as they can compete for resources and hinder each other's growth. Additionally, keep spinach away from fennel, as fennel releases compounds that can inhibit the growth of leafy greens. Finally, while not a direct conflict, avoid planting spinach near taller vegetables like corn or pole beans that could shade it out and reduce its access to sunlight.

Summer Squash

Summer squash, like other members of the Cucurbitaceae family, should not be planted near other cucurbits such as pumpkins, cucumbers, or melons. This close proximity can increase the risk of pest and disease spread, particularly squash vine borers and powdery mildew. Additionally, avoid planting summer squash near potatoes, as these can also harbor pests and diseases that affect cucurbits. Keep in mind that summer squash can cross-pollinate with other members of the squash and pumpkin families so if you're saving seeds, it's best to isolate different varieties. However, if you're simply growing summer squash for their fruit, cross-pollination won't affect the current harvest.

Tarragon

Tarragon, a flavorful herb with licorice notes, is a delightful addition to many culinary creations. However, its pungent aroma and specific growing preferences can make it a challenging companion for some plants. Avoid planting tarragon near any member of the Brassica family, such as cabbage, broccoli, and cauliflower. Tarragon's strong scent and compounds can inhibit the growth of these vegetables.

Additionally, it's best to avoid planting tarragon near rosemary. While both herbs thrive in sunny, well-draining conditions, their root systems can compete for space and resources, leading to less vigorous growth for both plants.

Thyme

Thyme is a versatile and fragrant herb that can enhance the flavor of many dishes and attract beneficial pollinators to your garden. However, due to its preference for dry, well-draining soil, it's best to avoid planting thyme near moisture-loving plants like mint or basil. These plants can create a humid environment that thyme dislikes, leading to potential fungal issues. Additionally, thyme should be kept away from brassicas, such as cabbage, broccoli, and cauliflower, as these plants have different soil pH preferences and nutrient requirements.

Tomatoes

Tomatoes, while a beloved staple in gardens across the globe, have a few foes they'd rather avoid. Most notably, keep them away from fellow nightshades like potatoes and eggplants, as they share susceptibility to devastating diseases like blight and verticillium wilt. Corn is another plant to avoid, as it's a heavy feeder and can outcompete tomatoes for nutrients. Additionally, fennel should be kept at a distance, as it releases compounds that can inhibit tomato growth.

Winter Squash

Winter squash, like its summer counterpart, should not be planted near other cucurbits such as pumpkins, cucumbers, or melons. This close proximity can increase the risk of pest and disease spread, particularly squash vine borers and powdery mildew. Additionally, avoid planting winter squash near potatoes, as these can also harbor pests and diseases that affect cucurbits. Keep in mind that winter squash can cross-pollinate with other members of the Cucurbita genus, so if you're saving seeds, it's best to isolate different varieties. 

Wrapping Things Up!

Understanding the complex relationships between plants is key to creating a thriving garden. By being mindful of which plants to keep apart, you can avoid unnecessary conflicts and create a harmonious environment where all your plants can flourish. Remember, every garden is unique, and experimentation is part of the fun. Observe how your plants interact with each other and adjust your planting strategies as needed.

If you have any questions or need further guidance on plant compatibility, don't hesitate to reach out to us at Southern Seeds. We're always happy to help you create a garden that's both beautiful and productive. Happy gardening!