Companion planting has long been practiced by gardeners looking to maximize crop yields, reduce pests naturally, and create a more balanced and biodiverse growing space. Among the many plants known for their companion benefits, nasturtiums stand out for their unique ability to support neighboring crops. With their vibrant flowers and sprawling foliage, nasturtiums do more than just beautify a garden—they function as hardworking allies to vegetables, herbs, and even fruiting plants.
In this guide, we’ll explore how nasturtium companion planting works, the science behind its benefits, how to integrate nasturtiums into your garden layout, and which plants benefit most from their presence. We'll also look at common mistakes to avoid and offer practical tips for maintaining healthy nasturtiums throughout the growing season.
What Are Nasturtiums?
Nasturtiums (Tropaeolum majus and Tropaeolum minus) are flowering plants native to South America. Known for their vivid red, orange, and yellow blossoms and rounded green leaves, they are both ornamental and edible. The leaves, flowers, and even the seed pods can be consumed, offering a peppery, slightly spicy flavor.
There are two main growth types: trailing and bush varieties. Trailing nasturtiums can sprawl over garden beds or climb trellises, while bush types stay compact and are ideal for borders or containers.
Why Use Nasturtiums in Companion Planting?
Nasturtiums offer a wide range of benefits to the plants around them:
1. Pest Control
Nasturtiums are known as a "trap crop"—they attract pests such as aphids, whiteflies, squash bugs, and cabbage loopers away from more valuable vegetables like tomatoes, squash, and brassicas. This makes them a natural and chemical-free method of integrated pest management.
2. Pollinator Attraction
With their bright, open flowers, nasturtiums are excellent at attracting pollinators such as bees, butterflies, and hoverflies. This increases the pollination rate of nearby crops and can improve yield.
3. Soil Protection
Their dense foliage helps shade the soil, reducing evaporation and suppressing weeds. This benefit is especially useful in hot climates or arid conditions where soil moisture is a concern.
4. Edibility
Every part of the nasturtium is edible. This means you're not just growing a flower to protect your vegetables—you're also gaining a salad ingredient or garnish.
Best Vegetables to Companion Plant with Nasturtiums
Nasturtiums are flexible and can be paired with a variety of garden crops. Below are some of the most beneficial pairings:
1. Tomatoes
Tomatoes are a favorite target of aphids and whiteflies—two pests that nasturtiums naturally attract away. Planting nasturtiums at the base of tomato plants can significantly reduce infestations and improve airflow at the soil line.
2. Cucumbers
Cucumber beetles are notorious for damaging cucumber plants. Nasturtiums can serve as a decoy, drawing these pests away from your cucumbers and potentially interrupting their life cycle.
3. Squash and Zucchini
Similar to cucumbers, nasturtiums help deter squash bugs and aphids. The trailing varieties can also sprawl through the squash patch, acting as a living mulch that conserves soil moisture.
4. Cabbage Family (Brassicas)
This includes broccoli, cabbage, kale, and cauliflower. Nasturtiums are very effective at distracting cabbage loopers, which lay eggs on the leaves of brassicas. They also deter flea beetles and other chewing insects.
5. Radishes and Carrots
Nasturtiums planted near root vegetables like carrots and radishes can help ward off pests like root maggots and carrot flies. They may also help break up the soil surface slightly with their shallow roots.
6. Beans and Peas
While not their strongest pairing, nasturtiums can still offer some pest protection to legumes, especially from aphids. The flowers also attract beneficial predatory insects like ladybugs, which consume aphids.
How to Incorporate Nasturtiums into Your Garden Layout
You don’t need to plant an entire bed of nasturtiums to reap their benefits. Strategic placement is key:
1. Border Planting
Use bush nasturtiums as a colorful and functional border along the edges of raised beds or garden rows. They’ll act as a first line of defense against pests.
2. Intercropping
Plant nasturtiums directly between rows of vegetables such as tomatoes, peppers, or lettuce. This not only saves space but also enhances pest protection.
3. Vertical Companions
For trellised crops like pole beans, peas, or cucumbers, trailing nasturtiums can be trained to climb the base or allowed to cascade over containers.
4. Container Gardens
Nasturtiums thrive in pots, especially trailing types. You can place these near your main garden or on patios and balconies for mobile protection.
Tips for Growing Healthy Nasturtiums
Nasturtiums are relatively low maintenance, but the following practices can help maximize their benefits:
1. Choose the Right Variety
Bush types are best for tight spaces, while trailing types are more useful for ground cover or trellising.
2. Don’t Over-Fertilize
Nasturtiums thrive in poor soil. Excess nutrients, especially nitrogen, can lead to excessive foliage growth at the expense of flowers—reducing their effectiveness at attracting pollinators.
3. Watering
While drought-tolerant, nasturtiums benefit from consistent but moderate watering. Avoid waterlogged conditions that lead to root rot.
4. Sunlight
These plants prefer full sun but can tolerate partial shade. Too much shade, however, may reduce flower production.
5. Deadheading
Removing spent flowers encourages continuous blooming and helps the plant channel energy into new growth.
What Not to Plant with Nasturtiums
Though generally friendly, nasturtiums may not benefit every crop:
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Potatoes: Both attract aphids and might compound the pest problem.
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Fennel: This plant secretes compounds that inhibit the growth of many neighbors, including nasturtiums.
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Brussels Sprouts: While related to cabbage, Brussels sprouts can sometimes attract pests nasturtiums also like, increasing risk without offering a clear benefit.
Enhancing Pest Control with Nasturtiums
To use nasturtiums more effectively as a trap crop:
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Monitor Pest Load: Check the undersides of nasturtium leaves often. If they are heavily infested, remove the affected leaves or entire plant before pests spread.
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Use as Decoys: In early spring, plant nasturtiums ahead of other crops. Pests will flock to the early growth, giving your vegetables time to mature without interference.
Companion Planting Beyond Pest Control
Nasturtiums can be part of a larger ecological system in your garden:
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Attracting Predators: Nasturtiums attract hoverflies, parasitic wasps, and ladybugs—natural predators of common garden pests.
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Supporting Soil Health: As they die back, nasturtiums can be chopped and dropped to return nutrients to the soil, functioning as a mild green manure.
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Boosting Aesthetic Appeal: Companion planting isn't just about function. Nasturtiums add a vivid splash of color, enhancing the visual appeal of your vegetable beds.
Companion Flowers That Pair Well with Nasturtiums
For those seeking to combine flowers with veggies, consider these companions:
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Marigolds: Also great for pest control and soil health.
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Calendula: Offers similar benefits and attracts pollinators.
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Chamomile: Can improve plant health and attract hoverflies.
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Alyssum: A dense groundcover that supports beneficial insects.
Final Thoughts
Nasturtium companion planting is a time-tested and organic method to improve garden resilience. From their natural ability to trap pests to their role in attracting pollinators, nasturtiums provide multifaceted support in a diverse garden. They offer beauty, utility, and flavor—all wrapped into one vibrant package.
By choosing the right partners, monitoring your garden for pest pressure, and integrating nasturtiums into your design, you’ll foster a more harmonious and productive growing environment. Whether you're an urban gardener working with containers or managing a large backyard vegetable patch, nasturtiums can play a valuable role in achieving your gardening goals.