The Best and Worst Tomato Companion Plants for Balcony Gardens

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Tomatoes are a popular balcony crop because they’re super easy to grow in pots. To maximize your yields and keep your plants healthy, make sure you add in some tomato companion plants too.

In this article, we’ll look at the best companion plants for tomatoes that work on balconies. Specifically, these help with nutrients, attracting pollinators, and deterring pests.

We’ll also cover what not to plant with tomatoes on balconies.

Tomato Companion Plants

1. Lettuce

Lettuces make good companion plants for tomatoes because they fit nicely beneath the trailing plant. Also, ground crops like lettuce help keep the soil cool and moist, which tomatoes like.

Any planter will do fine, but consider buying one with a trellis already fitted (like this). It’ll make training your tomatoes much easier.

2. Amethyst Zinnia

Amethyst zinnias (or any type of zinnias) are useful tomato companion plants. They deter pests, such as tomato worms, and attract hoverflies and predatory wasps. You don’t need to plant them in the same soil for this to work, as a nearby pot will do the job.

3. Carrots

Planting carrots in the same soil as your tomato plants helps to keep it loose, which the tomato roots prefer. Start the tomatoes off in the soil, and then add carrot seeds once they’re established. Providing you use a big enough pot (such as this), you shouldn’t disturb the tomato roots when you harvest the carrots.

4. Borage

Borage works well as a tomato companion plant because it deters tomato hornworms. You can either keep it in the same soil for cover – like lettuce – or plant it in a nearby pot.

5. Alliums

Alliums are the onion family, including garlic, leeks and onions. Gardening lore states they make good companion plants for tomatoes because their strong smell deters plenty of pests.

However, garlic is probably the only one you want to plant in the same soil because it’s small. If you grow onions or leeks in a tomato pot, you risk them impeding the tomato plant’s roots.

6. Nasturtiums

Nasturtiums draw pests, such as aphids and slugs, away from tomato plants. As such, you want them nearby but not too close – a few feet away should do. Nasturtiums are trailing plants and work best in either railing planters (like this) or ground pots. While they look great as hanging plants, pests won’t be able to reach them.

Another useful benefit of nasturtiums as tomato companion plants is that the flowers and leaves are edible. They work amazingly in a fresh salad with tomatoes and lettuce or arugula.

7. Basil

Basil is perhaps the most traditional accompaniment to tomatoes. Luckily, the plants enjoy growing near each other too. Basil helps repel pests, including fruit flies, and some gardeners believe it can improve the taste of tomatoes during their growth.

You can either plant it in the same soil, following the advice given above for lettuce and borage, or you can keep it in a nearby pot. You won’t get the potential flavor benefits if the plants aren’t sharing soil.

What Not to Plant with Tomatoes

There are plenty of companion plants for tomatoes but just as many enemies. Some of the most relevant for balcony gardening include:

1. Nightshades

Tomatoes are a member of the nightshade family, as are peppers, potatoes and eggplant. They’re all vulnerable to the same pests and diseases, so keeping them near each other in a small space is a recipe for disaster.

If you plan to grow any of these on your balcony, keep them as far away from your tomatoes as possible.

2. Corn

Both corn and tomatoes are preferred foods of Helicoverpa zea, known as both the corn earworm and the tomato fruit worm. As such, avoid growing both on your balcony.

3. Brassicas

Brassicas are the cabbage family, which includes broccoli, cauliflower, kale and more. They can stunt the growth of tomato plants, but only when kept in the same soil. It’s therefore a fairly easy problem to avoid if you’re growing crops in pots.

4. Fennel

Fennel is pretty much a no-go for balcony gardening because it releases a chemical that inhibits growth. Luckily, there aren’t many circumstances in which growing fennel is worthwhile, unless you like the look of it.

Final Thoughts on Companion Plants for Tomatoes

As you can see, there are plenty of tomato companion plants that work well on balconies. Better yet, you can use the advice for lettuces for loads of plants, including spinach, arugula, and more. However you’re growing tomatoes on your balcony, companion plants can make the project worthwhile.