Companion planting is one of those gardening topics where anecdotal experience comes before the scientific confirmation. A Minnesota Master Gardener study found no measurable yield benefits from common pairings like marigolds with tomatoes, but the study was small and only measured yields, not pest pressure or plant health.
I’ve grown tomatoes at HeathGlen Organic Farm for over 20 years, and I do plant basil, parsley, and marigolds near my tomatoes. Whether it helps the tomatoes or just makes the garden more beautiful and useful, the combinations work for me.
Here’s what’s considered beneficial, compatible, and incompatible based on decades of gardener experience.
Quick Summary: Companion planting pairs plants that may benefit each other through pest confusion, root chemicals, or resource sharing. Beneficial companions for tomatoes include basil, parsley, marigolds, and borage. Avoid planting tomatoes near brassicas (cabbage family), potatoes, fennel, or corn. Evidence is mostly anecdotal, but the combinations are low-risk and potentially helpful. Read time: 6 min | Experience level: Beginner
Jump to: Key Considerations | Best & Worst Combinations | Why It Works | FAQ
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Does Companion Planting Actually Work?
Many gardeners report benefits of companion planting; research is limited
A research study conducted by Minnesota Master Gardeners several years ago found no benefits of growing several plant combinations, including French marigolds with tomatoes. However, the number of growers who completed the study was small and the only information reported was about yields, not beneficial insects.
As the interest in organic growing and strategies like Integrated Pest Management (IPM) grows, so does attention to the potential benefits of companion planting.
Anecdotal information on the benefits of companion planting with tomatoes is plentiful.
What Are the Keys to Successful Companion Planting?
Here are some key considerations based on expert gardeners experiences:
- Marigolds are often listed as a good companion for tomatoes. You do need to know a few specifics for it to work however. In the book Carrots Love Tomatoes: Secrets of Companion Planting for Successful Gardening
author Louise Riotte notes that French marigolds need to be grown for at least a full season before they will control nematodes in the soil and thus be beneficial.
- Growing the plants close to one another can maximize the benefits. This could be a particular benefit in urban areas where the space considerations are limited.
- Avoid growing plants that might compete with each other. For example, one reason why tomatoes and asparagus are great companions is that they grow at different levels, in the soil, so they don’t compete with each other for water and nutrients,
- Another way to avoid competition is harvest time. Asparagus for example, will be harvested early in the year with tomatoes coming mid to late Summer.
What Plants Benefit Tomatoes?
Some plant combinations have a history of being beneficial, some are considered “compatible”, and there are some combinations considered harmful. Here is a current list of plant pairings for each of these categories:
Some of the pairings with tomatoes most often cited as helping improve the health and/or flavor of tomatoes include:
- bee balm,
- mint,
- basil,
- parsley,
- celery,
- and borage.
On the other hand, here are some combinations in which tomatoes help other plants:
- gooseberries
- peppers
- roses (potential protection against black spot).
What Plants Are Compatible with Tomatoes?
Among the vegetables and herbs generally considered to be compatible (but not necessarily beneficial) with tomatoes include:
- oregano,
- carrots,
- onions,
- radishes (discouraging two-spotted spider mites),
- garlic (protection against spider mites),
- amaranth,
- chives,
- stinging nettle,
- lavender,
- thyme, and
- lemon balm.
Flowers that are compatible with tomatoes include:
- marigolds
- geraniums,
- petunias,
- nasturtiums,
- pot marigolds (also known as calendula), and
- foxglove.
What Plants Should You Avoid Near Tomatoes?
A few combinations need be avoided:
- Most things in the brassica (cabbage) family
- Tomatoes and potatoes don’t grow well together.
- Some believe that fennel can inhibit tomato growth, and
- It is not recommended to grow tomatoes close to corn because of the similarity of pests that feed on each.
- Other plants that have been identified by some as poor companions with tomatoes are peas, beets, and rosemary.
Why Does Companion Planting Work?
One belief around companion planting is that the mix of smells confuses insects.
Another theory on companion planting is that chemicals in the leaves and/or roots of some plants have a positive impact on others (such as the possible effect on black spot noted earlier).
A third belief is that mixed plantings generally “mimic” nature by offering a diversity of plants that attract some insects and organisms while repelling others.
So, if you choose your companion plants from the lists above you will certainly get beauty, regardless of whether the growth benefits are proven
Comprehensive Guide to Companion Planting in General
This post focused on companion planting with tomatoes, and I have another post that focuses on companion planting with blueberries. If you want a more comprehensive look at companion planting in general, check out this guide from Homestead and Chill. They provide great information with charts and details on the subject!
FAQ
Research is limited and inconclusive. A Minnesota Master Gardener study found no yield benefits from marigolds with tomatoes, but only measured yields, not pest reduction. Most evidence is anecdotal, but the practice is low-risk.
Basil is most commonly cited. It’s said to improve tomato flavor and repel pests. Whether or not it helps the tomatoes, you’ll use both in the kitchen, so planting them together makes practical sense.
Both are nightshades and share pests and diseases. Planting them together increases the risk of spreading problems like blight between crops.
French marigolds may suppress nematodes in soil, but only after growing for a full season. They won’t provide immediate benefits. They do add color and attract beneficial insects.
Brassicas (cabbage, broccoli, cauliflower), potatoes, corn, and fennel. Brassicas and tomatoes compete for nutrients. Potatoes share diseases. Corn attracts the same pests. Fennel may inhibit tomato growth.
Yes, though space is limited. Basil and parsley work well in the same large container as a tomato plant. Marigolds can go in nearby pots.
For a detailed guide and journal for growing tomatoes, check out my Tomato Workbook on Amazon for $11.99.
Thank you for sharing this. The info was exactly what I was looking for. My small backyard is getting crowded & have a spot for my newly purchased tomatoe plant next to an established small rose plant. I will make them neighbors & see how it goes.
I’m a home gardener with a tiny in ground garden. I’ve been growing my tomatoes with basil and marigolds for years. Last year, I added purple majesty potatoes figuring they’d be ready for harvest before the tomatoes got big – WRONG. So I kept trimming back the potato Vines away from the tomatoes. I noticed that my tomato crop was far larger than usual so apparently my tomatoes loved those potatoes.
Thank you for sharing that Rachel! I don’t grow potatoes so that is helpful information that I’m sure others will appreciate.