The garden, oh the garden, why oh bugs do you love my garden? I don’t know about you, but one of the hardest things about having a garden is watching a beautiful tomato begin to grow, begin to ripen, and right when it is ready to pick…a tomato hornworm appears from nowhere and devours it! This is compounded all the more if no pesticides are used. Today, I will be sharing the top 5 companion plants for tomatoes to help you defend your plants against common garden pests.
Note: This post contains affiliate links. We earn a small commission at no additional cost to you. Read our disclaimer for more details.
What is companion planting?
Companion planting is the intentional action of planting 2 or more plants close to each other. My favorite book on the topic is carrots love tomatoes which covers a great array of potential companion planting options for tomatoes and many other crops. Frequently, this is done for one of three primary purposes. To deter pests, attract pollinators, or improve the flavor of the focus crop. I love tomatoes when it comes to companion planting as there are many options and fun combinations to experiment with. You may have a different pest impacting your particular crop than we have here in South Carolina, which makes experimenting in your garden all the more important. Here are my top 5 companion plants for tomatoes.
Basil
First off, I find it perfect that basil and tomatoes do well together as the flavors of these two plants are incredible both individually and together. Basil is fantastic for tomatoes as it can enhance the flavor. I have found the flavor of the tomato to be sharper, the sweetness a little more pronounced, and the acidity well balanced when planted near basil. So have fun planting some basil next to your tomato and see if it works for you as well!
Yield is always a challenging parameter to quantify and separate from all the free radicals of gardening. Even so, I have noticed consistently that tomatoes planted near basil yield slightly more than the tomatoes without the basil. This could be due to differences in light, fertility of the soil, better moisture retention, or a host of other potential influencing factors. Even so, it is fascinating to continue to observe to see if an improvement in yields survives the test of time.
The scent of basil can also help naturally repel the whitefly. These sneaky pests spread viruses amongst tomato plants especially well. As when they suck the sap of one plant that is infected, it can then spread to any other plant it visits. The whitefly also causes damages by sucking the phloem (think of the bloodstream of a plant) and diverting nutrition away from the plant. Thankfully, whiteflies do not like the aroma of basil. And by planting basil on the windward side of your tomatoes, you should see a reduction in the number of whiteflies visiting your garden this year.
Borage
If you have grown tomatoes for a couple of seasons, chances are you have spotted one of the more devastating pests that eat a tomato plants – the tomato hornworm. These impressive and ugly worms can consume whole branches of leaves and clusters of fruit. And they have a nasty habit of snacking on the prized tomato right before it ripens. When it comes to dealing with pests, I far prefer a good defense rather than having to find a strong offense. And dealing with the tomato hornworms are no exception.
Thankfully, borage is a helpful tool to naturally deter the tomato hornworms. The fragrant aroma of the flowers acts like a hornworm repellent, similar to the concept of using bug spray to keep the mosquitos at bay from us. By planting them throughout your garden every 6 feet or so, you should be able to maintain a good perimeter protection for your plants.
Borage also attracts pollinators. The blue or white flowers bring them in with their sweet nectar and thus closer to your tomato plants. Not only is this great for your tomatoes, but it also brings greater diversity to your garden. Creating an ecosystem to protect our friends the pollinators. And as a bonus, borage flowers are also edible! In addition to being beautiful, they also offer a delightful touch of cucumber flavor to any dish you add it to.
Marigolds
Another great flower to plant near your tomatoes is marigolds. Not only are they beautiful and add visual layers to the garden, but they also pull their weight by deterring some pests as well. Root nematodes can have a tendency to plague tomato plants. Making a seemingly healthy tomato plant shrivel, wilt, and sometimes die. These can be challenging pests to try and deal with. But I have found that marigolds can come to the rescue and help deter them. By having their root systems near each other, a symbiotic relationship is formed where the marigolds can gain access to some of the nutrients pulled up by the stronger tomato plant. In return, the marigolds keep the root nematodes at bay with its strong scent.
Marigolds also attract pollinators by the dozens! I have noticed pollinators on the flowers almost anytime throughout the day, which is fantastic for boosting the pollination rate for your fruiting crops. And the more diversity in the pollinators, the greater the chance of having good pollination for your tomatoes. Since marigolds are a shorter plant, it presents an excellent opportunity to get the plants in close to the tomato plants to offer the greatest impact with sharing pollinators.
Some other insects they attract are predatory insects that feast upon some of the pests of the tomato plant. Everything from praying mantis’s to green lacewings and ladybugs love the protection the marigold offers. Having more beneficial insects helps to create a natural balance to the insect populations while adding biodiversity to the ecosystem around your tomatoes.
Carrots
Carrots love tomatoes! This pair grows so well together even into the heat of summer. When planted at the same time, the carrots leaf out and begin to shade the soil providing an all-natural mulch to help keep soil temperatures cooler while retaining moisture. In return, tomatoes provide some partial shade to help keep the intense sunlight off the carrots. This can help boost their sweetness by preventing the carrots from turning bitter from the heat. Carrots are also great for loosening the soil. Our favorite variety in our heavy clay are the Ox Heart carrots. Their wedge shape help break the clay apart, enabling oxygen and moisture to penetrate further into the soil.
The combination of the two different root structures also help to symbiotically share nutrition that they uniquely access more readily. Whether it is the bringing up of phosphorus from the deep carrot roots or the holding of nitrogen with the shallower broad roots of the tomato. Both of these mutually benefit each other.
Lastly, it is always wonderful to be able to grow multiple crops in the same growing area. It may not be the most efficient for time management. If you are only working with a small garden area, however, it makes it possible to sometimes double your yield per square foot with this simply trick. I like these two crops together in particular as the carrots hold long enough in storage to wait for you to process the more perishable tomatoes before they go bad. Each of these small components makes this pair to be one of my favorites in the garden.
Lemon balm or mint
Last but not least of our top 5 companion plants for tomatoes is mint or lemon balm. But before diving in too far, one important disclosure is to plant either of the crops in a pot or planter. If this is not done, the mint or lemon balm could very well take over your property within a short period of time. Trust me when I say, these crops can get out of control! I have one mint patch in particular that started as one mint plant and now covers over 16 square feet in a bit over one year!
Okay, enough about the potential negatives. Here’s the good stuff! Both lemon balm and mint do a great job to deter a host of pests that can effect tomato plants. Aphids, ants, and flea beetles all flee from mint and the strong aroma it offers. This is wonderful as the aroma of mint can spread considerably downwind of it’s location. Rather than having to have a mint plant with every tomato plant, it is possible to have a good coverage to prevent pests with one plant every 4 tomato plants or so. And the larger the pot, the greater the range of protection.
With companion planting, nothing is guaranteed as there are too many variables to control. This is one of the components that makes it such a delight to experiment with. To try different combinations to see what works in your environment. These 5 companion plants for tomatoes have worked great for us and I hope they do for you as well. If you are planting transplants next to your tomatoes, check out our other post on how to plant transplants!