Why You Should Not Plant Cucumbers Near Tomatoes | Top 3 Reasons

Planting cucumbers near tomatoes does have some advantages, but there are numerous reasons why it’s best not to put these two plants right next to one another. One of the main reasons is that diseases such as phytophthora blight and mosaic virus can affect both of these plants. The disease can spread quickly between species.

This article will explore the top 3 reasons why you should not plant cucumbers near tomatoes at home.

3 Reasons Not to Plant Cucumbers Near Tomatoes

The main reasons not to plant cucumbers near your tomato plants include the following:

1. Diseases Can Spread Faster

Diseases can affect both cucumber and tomato plants, which means it is super-easy for these diseases to spread between the two. Once one of these plants gets the disease, it usually spreads very quickly to the other one, which means it will kill both your cucumbers and tomatoes very fast.

Two of the diseases that affect both cucumbers and tomatoes are Phytophthora blight and cucumber mosaic virus. Both plants can be infected and suffer quickly from these diseases.

2. They are Both Vining Plants

Both cucumbers and tomatoes are vining plants, and because of this, the sunlight that each plant type needs can be directly affected. The vines are invasive and grow rapidly, eventually becoming entangled in one another.

Cucumbers and tomatoes can prevent the sun from reaching the plants, which means they won’t get the light they need to grow and thrive. If you don’t want massive vines taking over your garden, it’s best not to plant cucumbers and tomatoes right next to one another.

3. They Share Nutrients and Other Resources

Both cucumber and tomato plants are heavy feeders with ravenous appetites, and if they’re planted next to each other they can start to compete. The soil may not have enough nutrients to keep both plant types alive.

Both plants need consistent amounts of nitrogen, phosphorus, potassium, calcium, magnesium and iron. Deficiencies can develop leading to yellowing leaves, poor growth and poor fruit development.

How Far Should Cucumbers Be Planted from Tomatoes?

Cucumbers usually need at least eight inches to grow because they have roots that spread about four inches on either side. It is best to plant cucumbers and tomatoes a minimum of 16 inches apart so that the roots of each plant have enough space to grow and remain alive.

You can plant them further apart than that, but keep in mind that 16 inches is the minimum that most experts recommend because you’ll need eight inches just for a cucumber plant to have enough room to grow.

What Can You Not Plant Around Tomatoes?

Besides cucumbers, here are a few other plants that shouldn’t be growing alongside your tomatoes:

  1. Anything in the brassica family: cabbage, kale, Brussels sprouts, broccoli, etc.
  2. Dill, walnut, or fennel; mostly because they will actually inhibit the growth of your tomato plants, preventing the tomatoes from turning out plump and juicy
  3. Other plants that share diseases with tomatoes, such as eggplant, corn, peppers, and potatoes
I like to grow basil and strawberries with my tomatoes.

What Should You Not Plant Near Cucumbers?

You don’t want other heavy feeders or fruits and veggies that share the same diseases planted next to your cucumbers. You don’t need other foods competing for resources or spreading diseases to the cucumbers, so here are other foods to keep away from them:

1. Any Type of Aromatic Herb

Aromatic herbs include peppermint and other mints, sage, and basil. Other herbs are acceptable, however, including oregano, catnip, chives, tansy, and dill. Oregano—which does have a nice scent—is an exception to this rule.

2. Potatoes

Since potatoes are heavy feeders just like cucumbers are, these two plants should never be planted next to one another. It’s best to plant potatoes in a different section of your garden from your cucumbers. There is just too much competition between the two plants!

3. Any Type of Melon

The problem with melons is that many of the same insects that love to attack cucumbers will also attack the melons, which is why melons and cucumbers should also be kept far apart. Insects would love munching on those sweet melons and then finding the pickling source nearby!

Best Companion Plants for Tomatoes

Just as there are plants to avoid placing around your tomatoes, there are also plants that go well with them. Here are a few of them:

1. Herbs

Certain herbs do great alongside tomatoes, including basil, parsley, garlic, sage, cilantro, and oregano. Some of these, such as oregano, can even reduce the number of weeds you find around your tomato plants. It’s also nice to have an herb garden along with the foods you’re growing.

2. Flowers

Certain flowers can help prevent certain pests from attacking your tomatoes. These include marigolds, sweet alyssum, wildflower blends, cosmos, and calendula plants. They also add a lot of beauty to your garden because many of them are so colorful.

3. Vegetables

Certain veggies make great companion plants for tomatoes, so they thrive when planted together. These include carrots, onions, celery, squash, beans, peas, lettuce, and radishes. This not only helps prevent certain pests and diseases, but it also makes for a much better-looking and attractive garden!


When you plant a garden, always learn which plants go great together and which ones don’t. When planting cucumbers and tomatoes, they need to be planted far apart, if in the same garden area at all. There are also foods that go well next to tomatoes or cucumbers and those that don’t.