8 Plants You Should Never Grow With Potatoes In The Garden

Growing potatoes in the garden is relatively easy and very satisfying. They can be planted early in spring, and a second crop can be planted in late summer. Potatoes grow well in the garden alongside certain companion plants, like herbs that attract beneficial insects, and vegetables with shallow roots that don't compete with them, like onions, shallots, and radishes. There are various plants that don't make good companions for potatoes, however, so it's good to be aware of them: these include nightshades, fennel, cucumbers, melons, carrots, and sunflowers, among others. 

Being members of the nightshade family, potatoes (Solanum tuberosum) attract certain insect pests, including aphids, cutworms, Colorado potato beetles, and hornworms. Some of these pests may be able to overwinter in soil. For this reason, gardeners should also rotate their potato planting to different sections of the garden every year, avoiding the same location at least three years in a row.

Potatoes are also known to deplete nitrogen in the soil due to being heavy feeders, which is another reason to practice crop rotation in the vegetable garden. Allow the soil's nutrients to replenish by planting crops near potatoes that add nitrogen to the soil, such as beans or peas. This helps prevent soil nutrition from becoming depleted too quickly. But it's still important to avoid planting other heavy-feeding plants near them, including beets, and deep-rooted brassicas like turnips and broccoli rabe.

Peppers, tomatoes, eggplant, and okra are all in the nightshade (Solanaceae) family, as are potatoes. These plants tend to compete for soil nutrients. Planting them close together means that the plants will compete for resources and won't thrive. As a result, they may become more vulnerable to bacterial or fungal diseases. Another reason to avoid planting nightshades together is that these plants are susceptible to similar insect pests, like Colorado potato beetles, and planting them in proximity to one another makes it easier for these pests to colonize and move between the plants more quickly.

Cucumbers are mostly water, so the plants need plenty of it to grow as their fruits mature. Potato plants also require a consistent amount of water to flourish. Planting cucumbers near potatoes means they will tend to compete for available water, so these two vegetable plants should not be planted near one another. However, one solution to this dilemma is to plant cucumbers in containers. Place the containers next to a fence or trellis to support the vines. This solution saves space too.

Some growing experts claim that brassicas (also called cruciferous veggies) should not be grown with potatoes because they prefer slightly acidic soil. Potatoes, on the other hand, prefer a slightly acidic to neutral soil, so there may be a pH imbalance. However, other gardeners think that shallow-rooted brassicas like cabbage or cauliflower don't compete for soil resources with potatoes and so can be grown successfully near them. To avoid any competition over soil nutrients, it may be best to keep these vegetables separate. This may help avoid flea beetle infestations too since the pest likes both crops.

Fennel, the crunchy, fragrant green vegetable that tastes slightly like anise, can be a somewhat tricky vegetable to grow. Even garlic, which normally grows happily beside most popular vegetables, is a poor companion plant to fennel and will fail to thrive in its proximity. Fennel contains compounds such as anethole that can inhibit the development of many other vegetables, including potato tubers. So sadly, these two root vegetables should not planted next to each other.

Like potatoes, melons also require large amounts of water to reach a robust size and develop good flavor. But competing for available water is not the only reason not to plant these crops together. These two plants also require a fair bit of space, and melon vines can easily and quickly overtake potato plants, entangling them in their fast-growing vines. Also, potatoes tend to attract various kinds of aphids, and these liquid-sucking insects can cause a lot of damage to melon vines, especially watermelons. 

Carrots are cool season root vegetables, commonly grown for an autumn harvest, as potatoes are, but growing these two earthy veggies next to each other isn't a good plan. Root vegetables (including turnips, carrots, and parsnips) grown too close together will compete for soil nutrients, and though potatoes are technically tubers, they also feed heavily on soil nutrients. For bigger, more robust carrots and potatoes, don't plant these two root vegetable favorites together. 

Like cucumbers, squash are also members of the cucurbit family, requiring abundant water to thrive in the garden. So these plants will tend to compete for water with potatoes, much like melons do. Another important reason not to grow potatoes and squash next to one another is that squash vines grow quickly, and their large leaves can cover potato plants. This prevents them from getting enough sun and obscures potential infestations of potato beetles, which need to be picked off frequently to avoid damage.

While it's great to have some red raspberries growing in your garden, these spreading perennial berries are not good companions for potato plants. Raspberries are susceptible to a number of diseases that can spread back and forth between them and other nightshades. Among the worst of the diseases areblight and verticillium wilt, both of which can cause enough damage that the current year's harvest can be destroyed. So while potatoes are excellent crops to grow, be careful what you plant with them.