We have nasturtium growing in our backyard and while it provides our garden with many benefits, we wanted to know if it has any companion plants of its own. So, I did some research to find out. Here’s what I found.
The best companion plants for nasturtium are fruit trees, nightshade fruits, cucumbers, and brassicas. Nasturtium benefits other plants by attracting pollinators and providing ground cover, while other plants provide it with benefits such as partial shade and soil nitrogen. Avoid planting with other ground covers.
So, while these are some of the companion plants for nasturtium, what benefits do they bring, and what are some other companions? Let’s take a closer look.
Benefits of Companion Planting
Companion planting is selecting specific plants to place together to achieve benefits, such as increasing pollination or repelling pests. Sometimes these benefits are one-sided, while others are mutual.
A famous example is The Three Sisters—planting corn, beans, and squash together. The corn provides a trellis for the beans to climb, the squash provides a ground cover, and the beans fix nitrogen in the soil. Plus, all of them provide food!
Here’s a list of the benefits that gardens gain from companion planting:
- Boost Pollination
- Repel Pests
- Prevent Weeds
- Fix Nitrogen
- Amend the Soil
- Cover the Soil
- Reduce Evaporation
- Provide a Living Trellis
- Maximize Space
- Produce More Food
If you’d like to learn more about the benefits of companion planting, check out my other post: The Top 10 Benefits of Companion Planting.
Benefits of Nasturtium
Before we jump into the top 10 companion plants for nasturtium, let’s take a quick look at the benefits nasturtium brings:
- Ground Cover
- Attracts Pollinators
- Repels Pests
- Produces Food
Nasturtium is one of my favorite companion plants because it’s not common to have an amazing ground cover that’s also a fantastic pollinator attractor. It also attracts some pests such as aphids and blackflies away from other, more sensitive plants (such as fruit trees). In this way, you can think of nasturtium as a “trap” or “sacrifice” plant for pests.
A cool fact about nasturtium is that its long flowers don’t produce glucose like other flowering plants, but sucrose (which is way sweeter and attracts more pollinators!). It also evolved in tandem with the hummingbird’s long tongue (source).
Because nasturtium is fairly tough and fast growing, it can be used to generate biomass and compost for other plants.
For example, in our garden, I dug a hole in our heavy clay soil, placed a bunch of clippings (including nasturtium), and planted tomato seedlings on top. Once the tomato plant’s roots reached the hugelkultur deposit of clippings, they exploded with growth. Even though we have an extremely dry climate, after doing this deposit and using leaves as mulch we barely had to water our tomatoes!
Lastly, nasturtium’s leaves and flowers are edible and go great in salads (adding a peppery taste, like watercress).
Now, let’s jump into the top 10 companion plants for nasturtium.
1. Fruit Trees
Fruit trees assist nasturtium by attracting more pollinators, shading the soil, holding groundwater, breaking up compact soil, and providing mulch (from their branches and leaves). Nasturtium also grows great in the partial shade of fruit trees. As a result, these two are one of the BEST companion plant pairings out there.
Nasturtium also attracts beneficial predators and repels some pests from fruit trees, such as the codling moth.
While any fruit tree will benefit from this flowering perennial ground cover, nasturtium grows best in USDA zones 9-11 (source), so you’ll likely find that tropical fruit trees are a slightly better companion than more temperate fruit trees. However, nasturtium can be easily grown as an annual in colder climates (as well as in containers).
Other companions for fruit trees and nasturtium include wildflowers, alliums, and cover crops.
While nasturtium provides a ground cover for nightshade plants, nightshades benefit nasturtium by providing an understory layer (see the graphic above for a visual). This means breaking up clay soil, shading the soil, and retaining water. The fruiting varieties of nightshade also attract pollinators for nasturtium.
Nightshade plants include:
Keep in mind that even though nightshade plants go well with nasturtium, they often cause trouble for other plants, such as fruit trees. The problems usually occur from encouraging pests or diseases for these plants.
Overall, avoid planting nightshades with most fruit trees, legumes, walnut, brassicas, corn, fennel, and dill.
However, carrots, alliums, basil, and oregano are good companions for nightshade plants
In my research for nasturtium companion plants, I’ve found many instances of gardeners mentioning their cucumbers have improved flavor and growth by planting nasturtium with it.
Nasturtium also helps cucumbers by attracting common pests away from the cucumbers such as aphids, whiteflies, and cucumber beetles.
However, nasturtium can compete with cucumbers if they’re both allowed to grow along the ground. Because of this, it’s best to provide your cucumbers with a vertical trellis while the nasturtium stays as a ground cover.
When grown on a trellis, cucumbers benefit nasturtium by creating partial shade, attracting pollinators, and deterring some pests with their spiky leaves and fruit.
Other companions for cucumbers include corn, dill, legumes, and marigolds. Because of their large leaves and vining aspect, cucumbers are a great companion to use in Three Sisters gardens.
Brassicas are a huge friend and companion to nasturtium. While any brassicas will work well, I found these to be the best when planted with nasturtium.
- Brussels Sprouts
As with nightshade, nasturtium benefits from the brassica’s understory effects. However, brassicas are fairly vulnerable to pests, which is where nasturtium can help. For example, nasturtiums trap aphids and repel blackflies from damaging the brassicas (source).
Just make sure your brassicas have enough growth before allowing your nasturtium to grow with them. Otherwise, the nasturtium can cover and suppress these veggies!
Avoid planting brassicas with nightshades or mustard. However, you can use a “neutral” plant (such as nasturtium) as a barrier in-between these plants. This also works to separate any other plants that are foes.
You can also check out brassica’s companion plants.
5. Cover Crops
Many legumes such as clover, peas, and runner beans (along with some grasses) are also called cover crops as they are great pioneer plants for depleted soils.
Cover crops are used to improve soil health by slowing erosion, retaining water, preventing weeds, and controlling pests and diseases. They’ve even been shown to increase crop yields.
In the drought of 2012, corn and soybean farmers reported a 9.6-11.6% yield increase when they used cover crops, likely due in part to the cover crop’s ability to add 50-150 pounds of nitrogen per acre.Source
These cover crops fix nitrogen in the soil by promoting beneficial bacteria which take nitrogen from the air and store it in the soil as nitrates for other plants to use (source). While nasturtium isn’t the most sensitive plant, it tends to grow much better if the soil is already healthy and established.
As many cover crops produce a lot of biomass, they can also be used to mulch nasturtium plants for even more nitrogen and other nutrients (as well as reducing evaporation).
With cover crops such as clover, you can even grow them in-between your fruit trees and nasturtium and run livestock through the alleys. Your livestock gets free food, many pests are deterred, and your nasturtium gets an amazing fertilizer in the form of manure.
While vining legumes and grass cover crops can work with nasturtium, you might find them competing or becoming smothered by the nasturtium. For this reason, tree or bush legumes such as pigeon peas often work best.
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Carrots are biennial root vegetables commonly grown as annuals, and also grow in zones 3-10. They help other plants like nasturtium by breaking up compact soils and repelling some pests such as onion flies.
Keep in mind that carrots need rich, loose, and well-draining soil. It’s fairly common for carrot growers to accidentally get baby carrots because the ground is too hard or compact for the root to grow (this happened to us).
However, the ground will loosen naturally over time as the roots of plants penetrate it. Roots are also great at slowing and holding groundwater.
Pro-tip: You can cut off the carrot tops and replant them. They’ll quickly regrow new carrot roots!
Along with nasturtium, plant carrots with onions, tomatoes, lettuce, legumes, and leeks. Avoid planting carrots near radish, parsnip, and dill.
Like carrots, radishes help nasturtium by fixing compact soils and reducing weeds. They also help other plants by repelling pests such as cucumber beetles and other squash pests (source).
Radishes grow quickly, so they’re not usually threatened by nasturtium’s ground cover. However, it’s a good idea to keep an eye on the radishes until they’re more mature.
When using radishes to amend compact soils, aim for larger radish varieties like daikon. Also, if you’re using your nasturtium to make salads, radishes will make a great addition!
Plant radishes with other companions such as cucumbers, buckwheat, nightshades, lettuces, carrots, and herbs like mint, dill, and oregano.
Celery is particularly vulnerable to aphids, and since nasturtium attracts pests like aphids and whiteflies away, they make a great companion pairing. Additionally, as celery prefers plenty of water to grow, the ground cover and water retention from nasturtium go a long way.
Celery is a hardy biennial but is usually grown as an annual. It does best in USDA hardiness zones 4-10.
Because of this small overlap in climate between celery and nasturtium, if you’re not in a tropical climate (zones 9-11) you’ll likely need to grow these two plants as annuals.
For best results, provide celery with at least 6 hours of sun and some afternoon shade.
Marigolds are a well-known companion plant (especially for potatoes) as they help manage the soil-borne populations of nematodes. This is also true for nasturtiums.
These nematodes often afflict home gardens and have no available chemical pesticide. Luckily, marigolds, are natural repellents against nematodes because they produce a substance called alpha-terthienyl, which is deadly for the nematodes.
For this reason, marigolds have been used as a cover crop in India for many hundreds of years in areas where nematode populations are high.
Of course, since marigolds are flowering plants, their appearance and nectar also attract pollinators such as bees, butterflies, and hummingbirds, which benefit nasturtiums.
Just make sure that you plant a true marigold from the genus Tagetes, not Calendula, which sometimes goes by the same common name. The LSU College of Agriculture recommends the ‘Tangerine’ variety.
So, what exactly are wildflowers?
Wildflowers are defined as any flower that has not been genetically manipulated (source).
- Bee Balm
- Queen Anne’s Lace
- Purple Coneflower
- Meadow Cranesbill
- Black-Eyed Susan
Wildflowers are an amazing addition to your garden, especially if they’re within range of your nasturtium plants. Ideally, this is around 25 feet or closer, but no more than 50 feet away as it maximizes the chances pollinators will visit both the wildflowers as well as your nasturtium’s flowers.
These varieties of wildflowers are especially appealing to pollinators and provide a good mix of nectar and pollen they can use as sugar and protein.
Wildflowers also attract beneficial insect predators such as birds, ladybugs, and beneficial wasps, which naturally keep pest populations down.
Here are some other beneficial flowers for nasturtium:
- Calendula (pot marigold)
Any of the above flowers work great as a companion plant for just about any fruit, vegetable, or herb plant. However, this isn’t an exhaustive list, so feel free to explore other wildflower varieties!
To see more companion flowers, check out my other post: The Top 10 Companion Flowers for Gardens, Vegetables, & More.
What Not To Grow With Nasturtium
Avoid planting other ground covers like sweet potatoes and strawberries. Additionally, avoid vining plants such as squash, zucchini, and grapes—unless you provide a vertical trellis for them. The goal with companion planting is to observe and adjust any overlap in niches or competition (although, some competition is healthy at times!).