Not long after I began gardening, I ran into a familiar problem: I had far more ambition than space. I was young, full of energy, and I wanted to grow it all—tomatoes, peppers, lettuce, carrots, onions, beans—but my modest garden plot didn’t have room for such big dreams. As I stood there that day, staring at the vast empty space between my tomato plants, I had a question—What could I plant there that would grow harmoniously with my tomatoes?
Naturally, my first thought was companion planting— an approach is centered around growing plants that benefit one another, usually by deterring pests. Indeed, much has been written about companion planting, however the list of tomato companions is limited and anyway, I wasn't asking so much of my companion plants. All I really needed was compatibility. I was looking for vegetables with complementary growth patterns or nutrient needs—ones that could share space without fighting for it like Cinderella’s jealous stepsisters.
Over the following years, I did a lot of experimenting on what to grow with my tomatoes. I learned which vegetables can grow quite harmoniously and which ones don't make good bedfellows (see what I did there?) In this article, I'm going to be sharing everything I've learned when it comes to picking tomato partners and hopefully help some other gardeners make the most of that precious space in their own gardens.
Onions: Space-Saving Sidekicks
I remember that day vividly—thirty heirloom tomatoes tucked into raised beds stretching from our house to the sidewalk. Did I mention I was land hungry? I looked at the three empty feet between each plant and thought, What a waste! I quickly turned my attention to crops that didn’t need much space. The first that came to mind? The humble onion.
I won’t bury the lede: the onions grew splendidly. Their growth cycle pairs beautifully with tomatoes. Onions are daylength sensitive—they grow leaves until daylight hits a certain threshold, then shift focus to forming bulbs. After that switch, no matter how much sun or nutrients you give them, they won't grow more leaves. What’s done is done—and in this case, that’s okay.
Here in central Iowa, we grow long-day onions that begin bulbing around late May. Since our last frost is around May 10th, tomatoes get transplanted in mid-May—just as the onions are finishing their leaf growth. By the time tomatoes are large enough to throw shade, the onions are already sizing up nicely.
It’s a perfect pairing: onions shine in the early spring months, and by the time the tomatoes take center stage, they don’t mind the living in their shadow.
Carrots: Underground Allies
I got the idea to grow carrots from the book Carrots Love Tomatoes. I mean, with a title like that, how could I not give it a try? Although I've yet to come across any scientific data to support this pairing, I've found that in practice it works quite well. I suspect the reasons are similar as for onions. Carrots are reasonably tolerant of cold temperatures and they mature fairly quickly—usually in around 60-70 days. This means that, like onions, you can plant the crop and have it mature before the tomato plants are very large.
One other benefit I've noticed is that harvesting carrots opens the soil and leaves deep voids into which water can flow. And since carrot harvests usually coincide with the onset of fruit formation in tomatoes, that extra water penetration can help the tomatoes escape the effects of drought, thereby preventing issues like blossom end rot and cat-facing.
Cucumbers: Ground-Crawling Counterparts
Tomatoes and cucumbers might not be the most obvious pairing, but when grown thoughtfully, they can play nicely together—especially in a raised bed. The key is to choose compact, bush-type cucumber varieties like Arkansas Little Leaf or Bushy Cucumber. These shorter vines don’t sprawl aggressively and can be easily trained to explore the soil surface around upright tomato plants.
This setup works especially well in raised beds, where cucumbers can cascade gently over the edges while tomatoes are supported vertically. It’s a win-win for space efficiency and airflow.
Just be mindful of their shared need for consistent watering—both crops are sensitive to irregular moisture and may develop bitter fruit or blossom-end rot if left thirsty. Also, because both are susceptible to fungal diseases like powdery mildew, make sure to space them adequately and avoid overhead watering to keep foliage dry and healthy.
I guess it makes sense. Cucumbers and tomatoes go together so well in the kitchen—why not in the garden? If only we could grow a feta cheese plant, we'd be in business!
Leafy Greens: Low-Growing Companions
When it comes to filling in space beneath your tomato plants, leafy greens like spinach and looseleaf lettuce are some of the easiest and most cooperative companions you can grow. These cool-season crops thrive in the dappled shade cast by taller tomato plants, especially as summer heat intensifies.
Because leafy greens are shallow-rooted and relatively undemanding, they don’t compete heavily with tomatoes for nutrients or water. In fact, tucking a few rows of greens along the outer edges of your tomato beds is a clever way to make use of space that might otherwise go bare.
That said, not all lettuces are ideal neighbors. Avoid planting heading types like iceberg near your tomatoes. These varieties need consistent, unrestricted access to both water and nutrients to form tight, market-style heads. Interplanting them with heavy feeders like tomatoes can stunt their growth and leave you with disappointing results.
Stick to fast-growing, cut-and-come-again greens, and you’ll enjoy a steady harvest of tender leaves while your tomatoes ripen overhead.
Peppers: Perfect Bedfellows with Tomatoes
When I grow peppers and tomatoes together, I like to tuck a pair of pepper plants near the edges of the bed, between each pair of tomato plants. This setup keeps the peppers in full sun, prevents them from getting crowded out by the larger tomato vines, and—best of all—makes harvesting a breeze.
Peppers and tomatoes are both members of the nightshade family, so it’s no surprise that they enjoy similar growing conditions: warm weather, full sun, and rich, well-drained soil. Their nutrient needs align too, which makes fertilizing straightforward.
To keep both plants happy:
Avoid crowding—good airflow is key to preventing fungal diseases.
Don’t overwater—peppers prefer drier soil than tomatoes.
Stick to one pepper type per bed if you save seed (or better yet, cage them)—hot peppers can cross with sweets.
Whether you're growing bell peppers, jalapeños, or something more exotic, planting them alongside tomatoes is a time-tested way to make the most of your garden space.
Green Beans: Compact Companions That Pull Their Weight
Green beans are one of the most compatible crops you can grow alongside tomatoes—especially if you're trying to make the most of a small garden. Bush varieties are the ideal choice here: tidy, low-growing, and productive without competing for space or sunlight.
In raised beds, bush beans fit easily along the edges or in the gaps between tomato plants, provided there's still airflow and enough light. Unlike tomatoes, they don't need staking, pruning, or coddling—and their quick maturity means you can succession sow them for multiple harvests.
As legumes, beans offer a quiet benefit to the garden: they fix nitrogen in the soil through a symbiotic relationship with bacteria. While this doesn’t directly feed nearby tomatoes during the same season, it helps build long-term soil fertility—especially when beans are rotated into beds previously used for heavy feeders.
Honorable Mention: Fragrant Herbs Like Basil, Chives & Thyme
While they might not fill baskets the way tomatoes or beans do, fragrant herbs deserve a place near your tomatoes. Basil, in particular, is more than just a culinary match—it’s a growth-friendly companion with shallow roots and low nutrient needs. Tuck a few basil plants at the corners of your tomato bed, and you’ll have easy access for snipping, plus a burst of aroma every time you brush past.
Chives, thyme, and other low-growing, aromatic herbs offer similar benefits. They don’t compete aggressively for space or nutrients and can help cover bare soil, conserving moisture and gently deterring pests. Just give them good drainage and a bit of sun, and they’ll quietly do their part to support the stars of the garden.
A quick note of caution: not all herbs make good companions—avoid fennel and mature dill, both of which can inhibit tomato growth. We’ll cover these and other less compatible plants in the next section.
Plants to Avoid Growing Near Tomatoes
While many plants make great neighbors for tomatoes, a few are best kept at a distance. These species may compete for nutrients, attract similar pests, or harbor diseases that can affect your tomatoes.
1. Corn, like tomatoes, is a heavy feeder, and the two are likewise vulnerable to similar pests—especially the corn earworm, which is also known as the tomato fruitworm. Planting them together increases the risk of an infestation.
2. Potatoes are close cousins to tomatoes and growing them together can promote the spread of soil-borne diseases like early and late blight. Crop rotation is also difficult when these two are planted together.
3. Fennel, although delicious, is notorious for inhibiting the growth of many garden vegetables, including tomatoes. Keep it well away from your beds.
4. Brassicas including Cabbage, Kale, Broccoli, etc. compete heavily for water and nutrients. They also thrive in slightly different soil conditions than tomatoes, making them less compatible as companions.
5. Dill (at full maturity) can suppress tomato growth. If you enjoy using both in the kitchen, plant dill in a separate bed or container garden.
Final Thoughts: Grow Smarter, Not Just Bigger
As any seasoned gardener knows, growing a great tomato crop isn't just about the tomatoes—it's about how everything fits together. Choosing the right companions can help you make the most of your space, simplify your garden care routine, and even improve your harvests. Whether you're sneaking onions between rows, letting cucumbers sprawl along the edges, or tucking basil in wherever it fits, these pairings offer more than convenience—they create a garden that works in harmony.
Companion planting isn’t magic, but when done thoughtfully, it feels like it. So experiment, observe, and don’t be afraid to mix things up. With the right partners, your tomatoes won’t just grow—they’ll thrive.
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