Tomatoes and peppers are some of the most rewarding plants to grow in a veggie garden (although, technically, they’re fruits).
Many gardeners can relate to the temptation to plant an extra two or three tomato plants, only to be completely overwhelmed by an abundant harvest later in the year. And, heaven forbid you plant an extra jalapeño or habanero.
Although there’s a lot of good advice on how to grow each individual crop, there’s some mixed information about whether or not you can grow them together.
As a general rule, you can grow tomatoes and peppers together in the same space. There are two potential risks for growing them together, although these are minimal:
- Increased risk of crop-specific pests
- Soil nutrient depletion
Consistent crop rotation, healthy soil management, and early response to pests will mitigate these risks.
So, why the mixed messages? Mostly because large-scale growers have the space to separate these crops, and in an ideal world, that’s exactly what gardeners should do. But, backyard gardeners have been successfully growing these two plants together for decades. So, ultimately, the decision comes down to available growing space.
Planting Tomatoes & Peppers Together: Pest Management
Peppers and tomatoes are both in the Solanaceae family, along with potatoes, tobacco, eggplant, false nightshade, deadly nightshade, and ground cherries.
The Solanaceae family hosts a wide variety of pests, including mosaic viruses, hornworms, armyworms, and nematodes, as well as being vulnerable to common pests like aphids and leaf miners (source).
This is the primary reason growers recommend separating tomatoes and peppers, along with all Solanaceae crops. However, tomatoes and peppers are more resilient than other Solanaceae crops, so it is more important to separate them from potatoes and tobacco.
There are two things that attract pests:
- A large population of target plants
- Stressed or sickly plants
Although some pests are universal (like aphids), many are specific to families. The more plants you grow in the same family, the more likely pests are to find your crops. This is why crop rotation plans emphasize separating plants from the same family, in the hopes that this will dissuade large infestations.
However, there is little difference between planting 10 tomato plants and 5 each of tomatoes and peppers. The end result is 10 plants in the same family. This is why many backyard growers can get away with planting multiple plants from the same family in the same space. The overall population is not on the same scale as a professional tomato or pepper farmer.
In fact, it is best to separate all plants within a family, even separating tomato plants from each other, to prevent pest infestations. But, again, this depends on available space.
In general, the more plants you grow within the Solanaceae family, the more you should focus on separating them to discourage pests.
Planting Tomatoes & Peppers Together: Soil Nutrition
Plants in the same family also tend to pull the same nutrients from the soil. This is another reason crop rotation schedules are an important part of soil management.
Plants within the Solanaceae family are considered heavy feeders. Tomatoes and peppers pull a large number of nutrients from the soil – especially during fruit formation.
If you plant too many heavy feeders in one area, you can deplete key nutrients, which may result in nutrient deficiencies during the season or in future crops.
You can prevent nutrient deficiencies by spacing heavy feeders throughout the garden and surrounding them with leafy greens, herbs, root crops, and legumes. These crops have shallow roots and pull less nutrition from the soil, which keeps the heavy feeders from fighting over water and nutrients.
Again, this is less about separating tomatoes and peppers, and more about keeping all plants in the Solanaceae separated from each other. If you only grow a few plants, this isn’t necessary. However, the more tomatoes and peppers you grow, the more likely you are to see deficiencies from growing them all in one place.
Plants in the Solanaceae family pull a lot of nitrogen, potassium, and calcium from the soil. Mix compost into the soil when you transplant, and use extra compost as mulch to improve nutrient density.
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Eggshells are recommended for improving calcium in the soil, but it takes a long time before the calcium breaks down enough to be available to plant roots. Instead of adding eggshells to the soil around your plants, add them to your compost pile or mix them into the soil at the end of the growing season where you plan on growing Solanaceae plants the following year.
Planting Tomatoes & Peppers Together: Seed Saving
Pest and soil management are important to current crops, but gardeners focused on seed saving have to make decisions based on future crops.
Occasionally, plants within a family can cross-pollinate, but this is not true for tomatoes and peppers. Rather, you must separate different tomato and pepper varieties from each other to maintain a pure genetic line.
For example, if you are growing Purple Cherokee slicing tomatoes and Black Cherry tomatoes, you have to keep them at least 25’ apart in order to prevent cross-pollination. The same rule applies to peppers.
The more space you put between varieties, the more likely you are to keep a pure line. However, this doesn’t have to be empty space; in fact, you can fill this space with other plants to reduce cross-pollination even more.
So, a gardener could plant a block of Purple Cherokee tomatoes, then a block of bell peppers, then a block of Black Cherry tomatoes, and then a block of jalapeños. Within each block, you could interplant root crops, leafy greens, herbs, flowers, and legumes.
This would help with pest management, soil nutrition management, and seed saving. Plants within the Solanaceae family are self-pollinating, but wind can blow pollen onto plants that are close by. The more obstacles you put in the way, like other plants or structures, the less likely they are to cross. Pollinators have a minuscule effect on cross-pollination within this family.
Planting Tomatoes & Peppers Together: Support Structures
One final consideration for growing these plants together is support structures.
There are two kinds of tomato plants: determinate (bush), and indeterminate (vining). Determinate plants are more compact and will not grow beyond a certain length/height. Meanwhile, indeterminate plants can grow longer throughout the season, which can be difficult to contain. Most heirloom varieties are indeterminate.
Pepper plants don’t grow as much as tomato plants, but they can become quite heavy when they are in production, so they may still require support. Peppers are denser and may become top-heavy, so a cage can give extra support and may prevent splitting or plants uprooting themselves.
It may be easier to plan and manage your garden if you separate determinate tomatoes from indeterminate tomatoes, and if you keep peppers separate from both. It has no effect on overall health, but it can keep the tangled mess of vining tomatoes away from the more structured determinate tomatoes and peppers.
This can also make it easier to build support structures. Indeterminate tomatoes can be pruned and tied to trellises, while determinate tomatoes and peppers perform better in cages. This is not as important when you are only growing a few of each plant, but in larger gardens, this separation can make it easier to tend to your garden.
For more information on planting and managing a vegetable garden, please read The Ultimate Guide to Watering Tomato Plants, and Pepper Plants Not Growing? These are the Most Likely Causes.