Vegetable Plants Not to Plant Next to Each Other

Companion planting is the practice of planting certain vegetables next to one another to maximize positive effects of each plant. For example, basil is a good companion plant for tomatoes because it camouflages the tomato scent, thus protecting it from predatory insects. But just as some plants have a positive impact on each other, some plants negatively affect each other and should be planted in different parts of your garden.

Tomato is one of the most popular garden vegetables, but it is not always a good companion. Cauliflower, peas, corn and broccoli are just a few vegetables that get a negative effect from its tomato plant neighbors. Many times vegetables don't grow well together because they compete for the same nutrients. In other cases, such as tomatoes and corns, both attract worms that thrive in similar habitats. Fennel and potatoes have a negative effect on tomatoes.

Strawberries are a popular addition to many vegetable gardens, but they are not always a positive addition. Broccoli, cabbage, cauliflower and Brussels sprouts should not be planted with strawberries. The fruit plant uses great amounts of nitrogen and phosphorus from the soil, depleting the nutrients the other plants need. When plants compete for the same nutrients, one or the other -- sometimes both -- do not thrive.

Avoid planting root crops such as potatoes next to other root crops -- they compete for nutrients at the same depth. Other vegetables negatively affected by growing next to potatoes are zucchini, tomatoes, summer squash and pumpkins. Those plants require more watering, while potatoes require less watering. If over watered, plant tubers began to rot and attract bugs that are harmful to the other plants. Beans naturally adjust nitrogen levels in soil, so avoid planting near plants, such as broccoli, onions and kohlrabi that thrive when planted in soil with a higher nitrogen content.

Though gardeners have been practicing companion planting for centuries, there's no specific scientific data proving that the method makes your garden plants thrive. Gardening expert Louise Riotte writes that companion planting is something the scientific community is beginning to take a closer look at the gardening practice. But companion planting is more than just folklore. Organic gardeners who use companion planting stand firm that mutual benefit of certain plants, such as tomato and basil, keep pests at bay and increases garden production. Companion planting also uses scientific methods by relying on plants such as beans to fix nitrogen levels in soil.