17 Plants and Vegetables You Should Not Plant Together

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Although many plants only require plenty of water and sunlight to grow, some of them are not very good friends. In other words, you should never plant them together if you want them to be healthy and thrive. The reasons vary from one plant shading the other to contagious diseases and even allelopathy, defined as one plant’s ability to chemically damage other plants. This is why you need to find out more about these plants and vegetables you should not plant together.

1. Tomatoes and Corn

Tomatoes and corn do not make for a good pair because the tall corn will cast a deep shade over tomatoes. In addition to this, both plants can suffer from the same fungi and the corn earworm, also known as the tomato fruit worm. Alternatively, you can pair tomatoes with chives and basil, while corn can be planted with pumpkins or beans.

2. Potatoes and Tomatoes

The potato plant is quite unfriendly to most other plants. Although they belong to the same family, they do not make for a good pair. Potatoes become prone to phytophthora when planted with tomatoes, which is also known as the potato blight. When you rotate your crops yearly, do not swap tomatoes with potatoes, either. Potatoes should not be mixed with melons, cucumbers, turnips, squash, and many more.

3. Cauliflower and Cabbage

You should not plant cauliflower and cabbage together. They are a nutritious addition to your edible garden, but they will suffer from a fungal disease that will make their roots swollen. This leads quickly to plant death because the swollen roots won’t be able to absorb water anymore.

4. Lonely Asparagus

Asparagus should not be planted with any other vegetable or fruit. This lonely veggie loves its space; otherwise, the growth is severely stunted. You should keep asparagus away from all of your other crops, including garlic and onions.

5. Alfalfa and Other Seeds

Alfalfa is, interestingly, not suitable for plantation at all. This is because it has a unique type of allelopathy that renders seed germination. This process occurs not only with other crops but also with its own seeds.

6. Melons, Squash, and Cucumbers

Keep these three edibles far away from each other because they are susceptible to the same pests and diseases. In other words, if one of them gets affected, all of your crops will be compromised. Also, squash loves its space, so avoid cramming it together.

7. Sunflowers and Other Plants

Sunflowers release chemicals through their roots that will affect any nearby plants. As a result, you should plant sunflower about 12 inches away from the rest of your plants. At the same time, you need to collect the seeds as soon as they get mature, before dropping on the ground, because they also release the same chemicals.

8. Marigolds and Beans

Marigolds populate many edible gardens because they are known for their pest-repelling properties. However, marigolds should not be planted together with beans, including peas, pole beans, or bush beans.

9. Radishes with Broccoli, Cauliflower, and Others

Radishes are quite friendly with other crops. In fact, it is recommended to plant them with cucumbers, carrots, beans, spinach, lettuce, peas, squash, and many more. Despite this, they do not make a good pair with broccoli, cabbage, potatoes, grapes, cauliflower, turnips, or kohlrabi.

10. Broccoli and Cauliflower

Cabbage, cauliflower, and broccoli might seem quite similar, which is true. This also means that they are susceptible to the same pests and diseases. It’s best to keep them far away from each other. Additionally, you cannot pair them with tomatoes, squash, strawberries, and even peppers.

11. Zucchini and Potatoes

Potatoes are extremely hungry for nutrients, so planting them next to each other means that potatoes will quickly deplete the nutrients in the soil, starving your zucchini. Both plants grow quickly, but you should plant zucchini with corn, beans, and even melons. Potatoes, in exchange, make great companions for thyme, beans, horseradish, and basil.

12. Onions and Garlic

As you’ve probably noticed from the previous section, it is not a good idea to plant together members from the same family. This also applies to the allium family, or onions and garlic, leeks, and shallots, among others. Otherwise, they will slow each other’s growth, and they are more prone to diseases and pests.

13. Cucumbers and Herbs

Cucumbers should be one of the first plants you add to your vegetable garden, especially as a beginner. Unfortunately, they do not thrive when planted together with tomatoes, potatoes, cauliflower, and all types of herbs, including lavender, cilantro, rosemary, and others.

14. Lettuce and Onions

Lettuce is quite a versatile and friendly plant that you can add next to most of your other plants. The main exceptions are kale, onions (of all types), and cauliflower. This is because lettuce requires the same nutrients as the onion family, while garlic and different types of onions produce chemicals that slow down its growth.

15. Carrots and Parsnips

As you might have guessed, carrots and parsnips are quite similar, so they are susceptible to the same pests and diseases. For instance, if your crops get infested with the carrot root fly, you are likely to lose your entire crop. Carrots are suitable companions for chive, rosemary, and sage, aromatic herbs that will repel insects. Parsnips, on the other hand, can be paired with peppers, tomatoes, and allium family.

16. Kale and Basil

Kale and basil are not very good friends, although you can plant your kale next to rosemary, sage, and others garden herbs. It is a delicious superfood, but make sure you protect it by pairing it with the correct plants.

17. Rosemary and Cucumbers

Rosemary can be planted together with numerous plants, especially cruciferous ones (kale, broccoli, and other similar ones). However, rosemary releases chemicals that are harmful to cucumbers, slowing down their growth.


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