Table of Contents
- Introduction
- Why Use Companion Plants with Dahlias?
- Top Flowers for Natural Pest Protection
- Filling the Gaps: Underplanting for a Full Look
- Designing with Height and Texture
- Season Extension: Companions for Early and Late Color
- Growing Dahlias with Edibles
- Tips for Success with Companion Planting
- Conclusion
- FAQ
Introduction
Choosing the perfect companions for your dahlias is one of the most rewarding parts of garden planning. There is a special kind of excitement that comes from watching a border transform into a tapestry of colors, textures, and heights. At Longfield Gardens, we enjoy helping you discover how different plants can work together to create a more vibrant and healthy backyard oasis.
Whether you are looking to protect your blooms from pests or simply want to fill in the gaps between stems, the right companions make all the difference. This guide explores the best flowers, herbs, and foliage plants to grow alongside your dahlias for a professional, layered look. We will cover how to select partners that share the same sun and water needs while enhancing the overall beauty of your landscape, and our companion plants for dahlias guide expands on these ideas.
By the end of this article, you will have a clear plan for creating a balanced garden that thrives from early summer through the first frost. Pairing dahlias with thoughtful companions is the simplest way to turn a beautiful flower bed into a stunning garden masterpiece, and our Dahlia Collections make it easy to shop the look.
Why Use Companion Plants with Dahlias?
Companion planting is the practice of growing different plants near one another for mutual benefit. In a dahlia garden, this strategy serves several practical purposes. It can help with pest management, improve soil health, and maximize the use of your garden space. Most importantly, it creates a visual depth that makes your garden feel full and lush.
Dahlias are the stars of the late summer garden, but they can sometimes look a bit sparse at the base. Their stems are sturdy and tall, but the lower foliage isn't always the main attraction. Adding lower-growing companions "tucks in" the dahlias, covering bare soil and keeping the roots cool. We often trial these combinations in our own gardens to ensure the plants play well together without competing for resources.
Another benefit is season extension. Dahlias take a little time to get going in the spring and early summer. By planting early-blooming companions, you can enjoy a colorful yard while your dahlia tubers are still waking up. As the season shifts into autumn, different companions can take over to highlight the rich, warm tones of your late-season dahlia blooms.
Top Flowers for Natural Pest Protection
One of the most effective ways to support your dahlias is to use plants that naturally manage garden visitors. Some plants act as "trap crops," drawing pests away from your prized flowers. Others attract beneficial insects that do the work of protecting your garden for you.
Nasturtiums as a Helpful Distraction
Nasturtiums are a classic choice for any flower bed. These cheerful annuals produce vibrant blooms in shades of orange, yellow, and red. They are particularly useful because they act as a trap crop for aphids. Aphids are often attracted to the succulent stems of dahlias, but they find nasturtiums even more appealing.
By planting nasturtiums nearby, you encourage aphids to gather there instead of on your dahlias. This makes it much easier to manage the health of your main flowers. Nasturtiums also have edible leaves and flowers, adding a peppery zing to your summer salads. They thrive in the same full sun that dahlias love, making them an easy addition to the border.
Marigolds for Soil and Surface Health
Marigolds are famous for their ability to deter pests both above and below the ground. Their roots release substances that can help manage certain types of nematodes in the soil. On the surface, their scent is known to discourage many common garden pests.
Beyond their protective qualities, marigolds are simply beautiful. The golden and copper tones of varieties like 'Queen Sophia' or 'French Vanilla' complement the warm palette of many white dahlias. They are low-maintenance and stay relatively compact, so they won't compete with your dahlias for sunlight.
Salvia and Beneficial Insects
Salvia is a powerhouse in the garden. Its spiky blooms provide a wonderful vertical contrast to the rounded, heavy heads of dahlia flowers. More importantly, salvia is a magnet for hummingbirds, bees, and butterflies. These visitors are not just beautiful to watch; they are essential for a healthy ecosystem.
Attracting predatory insects like ladybugs and lacewings is a natural way to keep pest populations in check. Salvia comes in a wide range of blues, purples, and reds. Deep purple salvia looks particularly striking when planted next to bright yellow or white dahlias.
Key Takeaway: Using protective companion plants creates a natural balance in your garden. This reduces the need for extra maintenance and keeps your dahlias looking healthy and vibrant all season long.
What to Do Next
- Identify any areas in your garden where pests have been a concern in the past.
- Select one or two "protective" plants like nasturtiums or marigolds to plant at the edges of your dahlia beds.
- Space these companions at least 12 inches away from the dahlia stalks to ensure good air circulation.
Filling the Gaps: Underplanting for a Full Look
Dahlias often grow quite tall, sometimes reaching four or five feet. This growth habit can leave the lower part of the plant looking a bit "leggy." Underplanting is the solution to this common garden design challenge. By choosing low-growing, spreading plants, you can create a living mulch that beautifies the ground level.
Sweet Alyssum for a Fragrant Carpet
Sweet alyssum is one of our favorite choices for filling in the front of a border. It grows as a low, dense mat of tiny, honey-scented flowers. It is incredibly easy to grow from seed or starts and will quickly fill in the bare patches around your dahlia tubers.
Because sweet alyssum is a "spiller" plant, it will soften the edges of your garden beds. It comes in white, pink, and purple. The white variety is especially effective at making the bright colors of your dahlias pop. It also helps to keep the soil moist and cool, which dahlias appreciate during the heat of July and August.
Dusty Miller for Silver Contrast
If you want to add a touch of sophistication to your garden, look no further than dusty miller. This plant is grown primarily for its soft, silvery-gray foliage. The lacy texture of the leaves provides a beautiful contrast to the broad, green leaves of the dahlia.
Silver is a "neutral" color in the garden, meaning it looks good with everything. Whether you are growing deep burgundy Thomas Edison dahlias—
— or soft pink Café au Lait varieties, dusty miller provides a clean, bright backdrop that makes the colors look even more intense. It is drought-tolerant once established and stays tidy throughout the season.
Verbena for Airy Movement
Verbena is another fantastic underplanting option. It produces clusters of small flowers on slender, wiry stems. This gives the plant an airy, transparent quality. It doesn't block the view of the plants behind it, but it adds a layer of color and movement at the base of the dahlias.
Trailing varieties are perfect for the front of a bed or for spilling over the sides of large containers. Verbena is also very attractive to pollinators, ensuring your garden is always buzzing with life. It is a tough plant that handles the sun well and continues to bloom until the first frost.
Designing with Height and Texture
A truly beautiful garden has layers. When you think about what is a good companion plant for dahlias, consider the plants that will stand behind them or beside them. Using plants with different heights and textures creates a sense of depth that draws the eye into the landscape.
Zinnias for Color Harmony
Zinnias and dahlias are a match made in heaven. They both love the heat, require full sun, and come in almost every color of the rainbow. Zinnias are generally a bit shorter than the tallest dinnerplate dahlias, making them excellent "mid-border" plants.
The daisy-like shape of a zinnia bloom provides a nice visual break from the complex, geometric petals of a dahlia. If you are planting a cut flower garden, zinnias are a must-have. They have a long vase life and the more you cut them, the more they bloom. This keeps your garden looking fresh and full all summer long.
Canna Lilies for a Dramatic Backdrop
If you want to create a tropical or high-drama look, try planting canna lilies behind your dahlias. Cannas have massive, paddle-like leaves that come in green, bronze, or even variegated patterns. They provide a solid wall of foliage that acts as a stage for your dahlia blooms.
The tall, architectural stems of cannas can reach five or six feet, ensuring they are seen even behind the largest dahlias. This combination is especially effective in large garden beds where you want to create a focal point. Both plants are "heavy feeders," meaning they appreciate rich soil and regular moisture, so they are easy to care for together.
Ornamental Grasses for Soft Texture
Ornamental grasses, like fountain grass or switchgrass, add a different element to the garden: sound and movement. While dahlias are bold and structural, grasses are soft and breezy. The fine texture of the grass blades contrasts beautifully with the large flowers and leaves of the dahlia.
In the late summer and fall, many grasses produce feathery seed heads that catch the light. This adds a magical quality to the garden as the sun sets. Grasses also provide winter interest after the dahlias have been lifted or cut back for the season.
Key Takeaway: Mixing bold dahlia blooms with airy textures and dramatic backdrops creates a professional, layered look. This approach makes your garden feel like a deliberate, well-designed space.
What to Do Next
- Look at your dahlia bed from a distance to see where it needs more height or fullness.
- Choose a backdrop plant, like canna lilies, for the very back of the bed.
- Add mid-height companions, like zinnias or cosmos, between your dahlia plants.
- Include at least one ornamental grass to add movement and sound to the space.
Season Extension: Companions for Early and Late Color
Dahlias are the undisputed kings of the late summer garden, but they don't start their show until the days get long and the soil gets warm. To keep your garden beautiful from spring through fall, you need companions that bloom at different times. Our Bloom Time guide can help.
Snapdragons for Early Season Interest
Snapdragons are excellent early-season companions. They prefer the cooler temperatures of spring and early summer, which is exactly when your dahlias are just beginning to grow. By the time the dahlias are ready to take over the spotlight in July, the snapdragons have often finished their first big flush of blooms.
This "hand-off" ensures that there is never a dull moment in your garden. Snapdragons come in various heights, from dwarf varieties for the front of the bed to tall stalks that can reach three feet. Their vertical flower spikes are a great preview of the vertical interest the dahlias will eventually provide.
Asters for a Grand Finale
As the season winds down and the nights get cooler, asters come into their own. These fall-blooming perennials produce masses of small, daisy-like flowers in shades of purple, blue, and white. They bloom at the same time that dahlias are putting on their biggest, most impressive display.
The cool tones of asters provide a stunning contrast to the warm oranges, reds, and golds of many fall dahlias. They also provide a vital source of nectar for bees and butterflies preparing for winter. Planting asters around your dahlias ensures that your garden remains a vibrant sanctuary until the very first frost arrives.
Growing Dahlias with Edibles
You don't have to choose between a flower garden and a vegetable garden. Many edibles grow beautifully alongside dahlias and even benefit from the partnership. This is a great way to make the most of a sunny spot in your yard.
Cherry Tomatoes and Dahlias
It might surprise you to learn that cherry tomatoes and dahlias make great neighbors. They both love full sun, rich soil, and consistent watering. Because both plants can grow quite tall, they can be staked together or grown against the same fence.
The bright red or yellow fruits of the tomatoes add a playful look to the flower bed. As a bonus, the tall dahlia plants can provide a little bit of shade for the tomato roots, helping to keep them cool during a heatwave. Just make sure to give both plants plenty of space so they don't shade each other out.
Herbs as Fragrant Companions
Many herbs are not only delicious but also serve as excellent companions. Cilantro and anise, for example, produce delicate, umbrella-shaped flowers that attract predatory wasps. These wasps are harmless to humans but are very effective at controlling garden pests.
Lavender is another fantastic choice. Its silver-green foliage and purple spikes look beautiful tucked around the base of dahlia plants. The scent of lavender is also thought to deter some unwanted insects. These herbs are low-maintenance and will thrive in the same sunny conditions as your dahlias.
Tips for Success with Companion Planting
While choosing the right plants is important, how you plant them matters just as much. To ensure all your plants thrive, follow a few simple rules of thumb. At Longfield Gardens, we believe that gardening should be simple and enjoyable, and getting the basics right is the key to success. For planting basics, see How to Plant Dahlias.
Right Plant, Right Place
Dahlias need at least six to eight hours of direct sunlight every day. When choosing companions, make sure they have the same requirements. A sun-loving dahlia will not be happy if its companion is a hosta that needs deep shade. Always check the light and water needs on the plant label before putting them in the ground. If you are unsure, check the Hardiness Zone Map.
Space to Breathe
One of the most common mistakes in companion planting is crowding. Dahlias need good air circulation to stay healthy and avoid issues like powdery mildew. When you plant companions, make sure they aren't physically touching the dahlia stems.
Leave a little "breathing room" between the base of your dahlias and their partners. This also makes it easier to get in and water the dahlias at the root level, which is the best way to keep them hydrated without getting the foliage wet.
Feeding and Watering
Dahlias are "heavy feeders," meaning they use a lot of nutrients to produce those massive blooms. When you plant them with other hungry plants, like zinnias or tomatoes, you may need to supplement your soil with a balanced fertilizer or compost.
Watering is also key. We recommend watering deeply once or twice a week rather than giving them a light sprinkle every day. This encourages the roots to grow deep into the soil, making the plants more resilient during dry spells.
Key Takeaway: Success comes from matching plants with similar needs and giving them enough space to grow. A well-spaced garden is a healthy garden.
What to Do Next
- Group your plants by their water and light needs before you start digging.
- Use a garden trowel to mark out the spacing for each plant, ensuring at least 12-18 inches of space for large dahlias.
- Add a layer of compost to the soil before planting to provide plenty of nutrients for all your "heavy feeders."
Conclusion
Creating a garden full of dahlias and their companions is a journey that brings color and life to your outdoor space. By choosing the right partners, you can protect your plants from pests, fill your borders with lush textures, and enjoy blooms from early spring through the end of autumn. At Longfield Gardens, we are here to support you in every step of your gardening adventure, and our All About Dahlias guide is a great next step.
The most important thing to remember is that there are no "wrong" choices if the plants share the same basic needs. Experiment with different colors and heights to see what brings you the most joy. Gardening is about discovery and the satisfaction of seeing your hard work turn into a beautiful reality.
- Use trap crops like nasturtiums to naturally manage aphids.
- Underplant with sweet alyssum or dusty miller to cover bare soil.
- Add zinnias and cosmos for a continuous supply of cut flowers.
- Ensure all companions share the dahlia's love for full sun and rich soil.
"A well-planned garden isn't just about the flowers; it's about the harmony between every plant in the bed."
We encourage you to explore our wide selection of dahlia tubers and companion plants to start planning your best garden yet. Happy planting! Before you order, review our Shipping Information.
FAQ
What is the best plant to grow with dahlias to stop pests?
Nasturtiums are one of the best choices because they act as a "trap crop" for aphids, drawing them away from your dahlias. Marigolds are also excellent for deterring soil-borne pests and attracting beneficial insects that keep your garden healthy.
Can I grow dahlias and zinnias together?
Yes, zinnias and dahlias make fantastic companions because they share the same sun and water requirements. They both bloom throughout the heat of the summer and come in a wide variety of colors that can be easily coordinated for a beautiful look.
What should I plant at the base of my dahlias?
Low-growing plants like sweet alyssum, verbena, or dusty miller are perfect for underplanting. They cover the bare stems at the bottom of the dahlia plants and help keep the soil cool and moist without competing for space.
Do dahlias need a lot of space when planted with other flowers?
Dahlias do need good air circulation, so it is important not to crowd them. We recommend leaving about 12 to 18 inches of space between the dahlia stalk and any companion plants to ensure they stay healthy and disease-free.