Can You Grow Potatoes and Tomatoes Together?

Thinking of growing potatoes and tomatoes together as companion plants? Before beginning a vegetable garden, it is important to plan what you want to grow and where you want to grow it. That’s because the plants you place side by side can influence each other’s growth, either positively or negatively. You don’t want to start your season off on the wrong foot by putting two plants that hinder each other’s growth next to each other. 

These are two of the most popular plants to grow, especially for beginners. This is likely due to their popularity in the kitchen. But it’s also because they are relatively easy plants to care for, with the right knowledge. 

You may be tempted to grow these plants in the same space, but how will they impact each other’s growth? Let’s find out. 

What is Companion Planting? 

Companion planting is a term commonly used in gardening and agricultural circles. While in practice, companion planting has been around for centuries, the term rose in popularity within the gardening industry around the 1970s. 

The organic gardening movement prompted gardeners to think about how to optimize plant groupings and spacing to maximize yield. The idea behind the practice was that certain plants could improve each other’s growth when planted together, either due to the growing conditions created or the pest benefits provided. 

Today, companion planting is common practice in home gardens. This encompasses grouping plants of similar conditions together, allowing them to share soil, water, and light without competition.

But it also focuses on plant pairings that, due to their growth habits or compositions, actually improve each other’s growth by altering the soil, deterring pests, providing shade, and a range of other benefits. 

The Benefits of Companion Planting 

There are many purported benefits to companion planting, each applying to different groupings of plants. 

The first, and most obvious benefit, is physical. If you have a vegetable that needs a little more shade than others, like leafy greens, you can plant a tall, trellised plant, like beans, to provide some afternoon shade.

This allows you to improve the growth of both the plants (the beans get more sun and the greens avoid scalding). This is accomplished simply by placing them together and planting them in the right orientation. 

Companion planting is most often favored for its effectiveness against pests. Some plants have the ability to suppress or repel certain pests due to the chemicals in their roots. Others release a strong smell that some pests don’t like.

By planting these plants near vegetables the pests do like, you’ll create a protective barrier that keeps harmful pests out. And you’ll do it without the use of pesticides.

Trap Crops 

Trap crops perform a similar task, but rather than repelling the pests, draw them towards the companion plant. This keeps the pests focused on the trap crop and away from the plants you want to harvest. Nasturtium is one of the most common trap crops. It’s loved by aphids, keeping them away from the other vegetables in your garden. 

Another companion planting benefit can be found in the soil. Plants impact the nutrient levels in the soil, either because they take up certain nutrients more and leave others, or because they return nutrients to the soil (in the case of nitrogen-fixers). Good companion plants don’t compete or harm each other. They work well together with regards to nutrients, maintaining good soil health. 

These benefits also have an antithesis – some plants are not good companions and will inhibit each other’s growth. Either they attract the same pests or diseases that increase the risk of spread, or they emit chemicals that prevent the growth of the other. Bad companions also compete for nutrients or have incompatible growing conditions. These conditions end up resulting in the one plant dying while the other fights to survive. 

Does Companion Planting Really Work? 

The jury is still out on whether some of the companion planting benefits are proven or anecdotal. There is certainly plenty of pseudo-science surrounding the practice, so it’s difficult to know whether the theories are true or not. 

While some benefits may not be proven under vigorous research conditions, particularly the claims about vegetables emitting certain chemicals that improve growth, there are some benefits that just make sense.

Any of the physical benefits of companion planting, such as providing shade or wind protection for shorter plants. This doesn’t need to be tested – the proof is visible. 

Others have been tested in small studies and have proven effective. The use of marigolds to deter some pests has been tested, as well as the nitrogen-fixing properties of legumes. The ability of plants to attract pollinators to serve other plants is another proven benefit. It’s known to increase pollination and, as a result, yields. 

The effects of trap crops are also visible. Gardeners have seen swarms of pests flocking to trap crops to avoid their other plants. One or two strays may find their way off the plant. However, effective trap crops are effective due to their ability to attract pests so strongly that they aren’t interested in other plants. 

Companion planting certainly won’t cure all your gardening ills. But it does have a long list of benefits that can be seen in home gardeners across the world.

The unproven claims of some companion planting benefits shouldn’t taint the practice as a whole, which can help prevent a number of gardening problems and improve conditions for your plants in the long run. 

Can You Plant Tomatoes and Potatoes Together? 

With the basics of companion planting covered, let’s get down to the plants in question – potatoes and tomatoes. 

Tomatoes and potatoes do not look related, and their growth habits are certainly completely different. Sweet potatoes are perrenial veggies, and quite popular to plant at certain types of year.

While they may not look exactly alike, these plants are actually very closely related. In fact, if you’ve ever taken a look at the label when buying a tomato or potato, you’ll notice this relation in their scientific names – Solanum lycopersicum and Solanum tuberosum. 

These plants are both parts of the Solanaceae family, also known as the Nightshades. This family includes a range of edible plants, including eggplants and bell peppers. 

Because they are so closely related, they compete for the same nutrients in your garden. This means that tomatoes and potatoes should not be planted next to each other. This is a common potato planting mistake that many new gardeners make.

Pests and Diseases

You may assume that plants in the same family grow well together. However, companion planting tomatoes with potatoes next to each other increases the chances of one thing you don’t want in your garden – disease.

Both plants are susceptible to incredibly common diseases that will decimate your crop: early blight and late blight. Placing these plants next to each other greatly increases your chances of one plant encountering blight. This inturn, will spread it to the other plant, ruining them both. 

They also share similar pests, making your chances of an infestation far more likely. Beyond that, these plants appreciate the same nutrients, as do other nightshade plants, competing for what’s available in the soil and stifling each other’s growth. 

While that is the most important reason to avoid planting tomatoes and potatoes together, there are other practical considerations that make these plants bad companions. The growth habits of these two vegetables are completely different. When harvesting potatoes, you need to pull the tubers out of the ground. Tomatoes have incredibly deep root systems that will undoubtedly be disturbed by your potato harvesting if they are close together. 

Final Thoughts 

Ultimately, it’s best to keep these two plants far away from each other. It’s not a good idea to companion plant a potato next to tomatoes. It’s recommended that you don’t use the same soil as one another the following season.

This limits your chances of blight and other pests and prevents the depletion of shared nutrients in the soil. Keep tomatoes and potatoes on opposite sides of the garden, or grow in containers. This way, you can enjoy both vegetables without hassle.