Table of Contents
- Introduction
- Why Dahlias Benefit from Companion Plants
- Best Annuals to Grow with Dahlias
- Perennials for a Permanent Dahlia Border
- Using Herbs as Functional Companions
- Design Strategies: Choosing the Right Colors and Textures
- Practical Tips for Planting and Spacing
- What Not to Plant with Dahlias
- Creating a Cutting Garden with Dahlias
- Conclusion
- FAQ
Introduction
There is a unique kind of excitement that comes with planting dahlia tubers in the spring. We look forward to those first sprouts with the knowledge that by late summer, the garden will be a riot of color and texture. Dahlias are the undisputed stars of the late-season landscape, offering everything from petite pom-poms to massive dinnerplate dahlias blooms. While they are stunning on their own, the right companions can turn a simple flower bed into a breathtaking, professional-looking display.
At Longfield Gardens, we believe every garden should be a source of joy rather than a list of chores. Choosing the right neighbors for your dahlias is one of the easiest ways to ensure your garden looks full and vibrant from early summer until the first frost. If you are not sure of your growing zone, check our Hardiness Zone Map. This guide is for any home gardener looking to enhance their flower beds with plants that support, protect, and highlight the beauty of dahlias.
In the following sections, we will explore the best annuals, perennials, and herbs to grow alongside these spectacular flowers. For a broader overview, see our All About Dahlias guide. You will learn how to choose plants that share the same sun and soil needs while creating a balanced aesthetic. By selecting the right companions, you can enjoy a healthier garden and a longer season of continuous color.
Why Dahlias Benefit from Companion Plants
Dahlias are incredibly versatile, but they do have a few specific characteristics that make them great candidates for companion planting. Most dahlias are "heavy feeders," meaning they need plenty of nutrients and water to produce those famous blooms. They also love the sun and require well-drained soil to keep their tubers healthy.
Integrating other plants around your dahlias serves several practical purposes beyond just looking pretty. First, dahlias can sometimes have "bare legs." As the plants grow tall, the bottom foot or two of the stems can look a bit sparse. Low-growing companions can act as a living mulch, covering the soil and hiding those woody lower stems.
Second, dahlias are late bloomers. Depending on when you plant them and your local weather, they typically start their peak show in mid-to-late summer. Planting earlier-blooming companions ensures your garden is full of life while the dahlias are still putting on size. Finally, certain plants can actually help manage common garden visitors, like aphids or slugs, by attracting beneficial insects or acting as a natural deterrent.
Key Takeaway: Companion planting is about balance. The best neighbors for dahlias provide visual interest, fill seasonal gaps, and help maintain a healthy environment without competing for the same resources.
Best Annuals to Grow with Dahlias
Annuals are perhaps the easiest companions to pair with dahlias because they share the same life cycle. They grow fast, bloom hard, and usually prefer the same sunny spots. Because annuals only live for one season, you can experiment with different combinations every year.
Sweet Alyssum
Sweet alyssum is a fantastic "spiller" and groundcover. It stays low to the ground and produces a carpet of tiny, honey-scented flowers in white, purple, or pink. Because it stays small, it won’t compete with your dahlias for sunlight. It is perfect for tucking into the front of the border to soften the edges of the bed and hide the base of the dahlia plants.
Cosmos
If you want an airy, whimsical look, cosmos are a perfect choice. They have feathery, fern-like foliage that provides a beautiful texture contrast to the broad, heavy leaves of a dahlia. Varieties like 'Sensation Mix' offer shades of pink and white that look lovely next to softer dahlia colors like Cafe au Lait. Cosmos are also great for attracting pollinators, which is always a win for the garden.
Zinnias
Zinnias and dahlias are like cousins in the garden. Both are "cut-and-come-again" flowers, meaning the more you harvest them for bouquets, the more they bloom. Zinnias come in almost every color imaginable. To keep the garden looking intentional, try matching the color of your zinnias to the centers or highlights of your Break Out dahlias.
Snapdragons
Snapdragons are excellent for early-season color. They often start blooming in late spring or early summer, just as your dahlias are starting to gain height. By the time the heat of mid-summer arrives and the snapdragons begin to fade, your dahlias will be ready to take over the spotlight.
Nasturtiums
Nasturtiums are both beautiful and functional. These trailing plants produce cheerful blooms in warm tones of orange, red, and yellow. Many gardeners use them as a "trap crop." Aphids are often attracted to nasturtiums first, which can help keep them away from your prized dahlias. Plus, the round, lily-pad-shaped leaves provide a unique visual break in the garden.
What to do next:
- Choose 2–3 annuals that match the sun requirements of your dahlias.
- Check the mature height of the annuals to ensure they won't shade out your dahlia sprouts.
- Plant low-growing annuals like alyssum at the very front of the bed.
- Consider the color palette—do you want a monochromatic look or a high-contrast mix?
Perennials for a Permanent Dahlia Border
If you have a dedicated spot for your dahlias, planting perennials nearby can provide a permanent structure to the garden. The key is to choose perennials that are "well-behaved" and won't spread aggressively into the space where your dahlia tubers need to grow.
Salvia
Perennial salvias, such as the deep purple 'May Night' or the vibrant 'Caradonna', produce upright spikes of flowers. These vertical lines provide a striking contrast to the round, heavy shapes of dahlia blooms. Salvia is also a magnet for hummingbirds and butterflies, which adds movement and life to your backyard.
Verbena bonariensis
This is a favorite among garden designers. Verbena bonariensis grows on tall, wiry stems that are almost invisible, making the clusters of tiny purple flowers look like they are floating in the air. Because the foliage is so sparse, it doesn't block the light, allowing it to mingle beautifully between taller dahlia varieties.
Yarrow (Achillea)
Yarrow produces flat-topped flower clusters that offer a completely different geometry than dahlias. It is extremely hardy and thrives in the same well-drained soil that dahlias love. Varieties in soft yellow or terracotta can enhance the "sunset" tones found in many decorative dahlias.
Phlox
Garden phlox offers large, fragrant flower heads in mid-to-late summer. Since they bloom at roughly the same time as dahlias, they can be used to create a massive wall of color. Just be sure to leave enough space between the plants to ensure good airflow, which helps keep all your plants healthy during humid summer months.
Ornamental Grasses
Grasses like Pennisetum (fountain grass) or Stipa (feather grass) add a soft, rustling sound and a delicate texture to the garden. They catch the light beautifully in the late afternoon. As the dahlias provide the bold color, the grasses provide the "filler" that makes the garden feel natural and established.
Key Takeaway: When choosing perennials, look for plants that offer different flower shapes—spikes, flat heads, or airy clusters—to create a visually interesting landscape.
Using Herbs as Functional Companions
Herbs are often overlooked in the flower garden, but they make excellent companions for dahlias. If you want more ideas for scent-rich combinations, see our How to Design a Fragrant Garden. Many herbs have strong scents that can help mask the scent of plants from certain pests, and their delicate flowers are wonderful for attracting beneficial insects like lacewings and predatory wasps.
Anise and Cilantro
When left to go to seed, anise and cilantro produce umbrella-shaped flower heads (umbels). These flowers are highly attractive to tiny beneficial wasps that help keep aphid populations in check. They are lightweight and won't compete with dahlias for space or nutrients.
Artemisia
Silver-foliaged plants like Artemisia (such as 'Powis Castle' or 'Silver Mound') are fantastic for creating a visual break between bright dahlia colors. Beyond their beauty, the scent of Artemisia is known to be less than appealing to slugs. Planting a border of these silver plants can act as a helpful deterrent for these common garden visitors.
Dill and Fennel
Much like cilantro, dill and fennel produce beautiful yellow or green flower heads that look stunning in a "cottage garden" style arrangement. Their feathery foliage adds a soft touch to the sturdy appearance of dahlia stems.
What to do next:
- Incorporate herbs into the edges of your dahlia beds.
- Allow some of your culinary herbs to "bolt" or go to flower to benefit local pollinators.
- Use silver-leaved herbs to highlight the vibrant colors of your favorite dahlia varieties.
Design Strategies: Choosing the Right Colors and Textures
Creating a beautiful garden is about more than just picking plants that grow in the same conditions. It is also about how those plants look together. Dahlias come in such a wide range of colors—from the creamy white of 'Snow Country' to the moody, dark purple of Thomas Edison—that the design possibilities are endless.
The Warm Palette
If you love a garden that feels like a summer sunset, focus on dahlias in shades of orange, yellow, and red. Pair these with bronze-leaved plants or annuals like 'Profusion' zinnias and orange nasturtiums. This creates a high-energy, vibrant look that stands out even from across the yard.
The Romantic Palette
For a softer, more classic look, choose dahlias in shades of blush, lavender, and white. Varieties like 'Cafe au Lait' or 'Break Out' are famous for their romantic, oversized blooms. Pair these with silver-leaved plants like Dusty Miller, white sweet alyssum, and pale purple salvia. This combination feels cool and refreshing during the heat of August.
Playing with Texture
Texture is often the secret ingredient in a professional-looking garden. Dahlias have very solid, substantial leaves and flowers. To make them "pop," you need to surround them with something fine and delicate. This is where ornamental grasses, cosmos, and the wiry stems of Verbena bonariensis really shine. The contrast between the "heavy" dahlias and the "light" companions creates a sense of depth.
Succession Planting for a Long Season
One of the best ways to use companions is to plan for the "before" and "after." Dahlias take time to wake up in the spring. You can plant spring-flowering bulbs like tulips or a colorful allium collection in the same bed. By the time the bulbs are finished blooming and their foliage is fading, the dahlias will be growing tall enough to hide the dying bulb leaves. This keeps your garden bed looking tidy and productive all year long.
Key Takeaway: Think of your garden in layers. Use low-growing plants for the front, airy "see-through" plants in the middle, and tall dahlias or grasses in the back to create a full, lush appearance.
Practical Tips for Planting and Spacing
While it is tempting to pack as many plants as possible into a beautiful border, dahlias need their personal space. Good airflow is one of the most important factors in keeping dahlias healthy throughout the season.
Respect the Spacing
Most dahlia tubers should be planted about 18 to 24 inches apart, depending on the variety’s mature size. For a fuller look at spacing, see our How Far Apart Should I Plant Dahlia Tubers?. When adding companion plants, make sure you aren't planting them directly on top of the dahlia tubers. Leave a small radius around the dahlia's main stem to allow for watering and to ensure the dahlia doesn't have to fight for nutrients.
Water and Feed Correctly
Dahlias are thirsty and hungry plants. When you have a mixed bed with many companions, the competition for water can increase. A deep soaking once or twice a week is usually better than a light daily sprinkle. This encourages the roots of all your plants to grow deep into the soil. If your soil is sandy, you may need to water more frequently than if you have heavy clay soil.
Support the Tall Varieties
Many dahlias, especially the dinnerplate and decorative types, can grow 4 or 5 feet tall. They will need staking to prevent them from toppling over during a summer storm. By planting sturdy companions like bushy salvias or small shrubs nearby, you can provide a bit of natural wind protection, though a sturdy stake is still the most reliable method for the heaviest blooms.
What to do next:
- Mark the spot where you plant your dahlia tubers so you don't accidentally dig them up when planting annuals.
- Monitor the soil moisture—if the companions look wilted, your dahlias probably need a drink too.
- Apply a balanced fertilizer to the whole bed in early summer to support the heavy feeding needs of the dahlias.
What Not to Plant with Dahlias
While many plants make great neighbors, there are a few types of plants that are better off in a different part of the garden. Successful gardening often comes down to matching the plant to the right place.
Water-Loving "Bog" Plants
Plants that require soggy, constantly wet soil (like certain irises or marsh marigolds) are a poor match for dahlias. Dahlia tubers are sensitive to standing water and can rot if the soil doesn't drain well. Always stick with companions that prefer "well-drained" conditions.
Aggressive Groundcovers
Avoid planting aggressive, mat-forming groundcovers like ivy or certain types of sedum directly around the base of your dahlias. These can create a thick carpet that makes it difficult for dahlia sprouts to break through the soil in the spring. They can also make it harder for you to dig up your tubers in the fall if you live in a cold climate.
Heavy Shade Lovers
Dahlias need at least 6 to 8 hours of direct sunlight to bloom their best. If you plant them near large, dense shrubs or under the canopy of a tree, they will likely grow tall and spindly with very few flowers. Ensure all your companions in a dahlia bed are sun-lovers as well.
Desert Cacti and Succulents
While some succulents like well-drained soil, they often prefer much drier conditions than a dahlia requires. If you water your dahlias enough to keep them happy, a desert cactus in the same spot might suffer from too much moisture.
Creating a Cutting Garden with Dahlias
Many people grow dahlias specifically for flower arrangements. If this is your goal, your companion planting strategy might focus more on "fillers" for your vases. A dedicated cutting garden doesn't have to look like a farm; it can be a beautiful part of your landscape. See our How to Design a Cutting Garden for more planning ideas.
For a great cutting garden, plant dahlias alongside other "filler" flowers like:
- Ammi majus (False Queen Anne’s Lace): Provides a delicate, lacy white look.
- Eucalyptus: Offers beautiful silvery-blue foliage that lasts a long time in a vase.
- Bupleurum: A unique green filler that adds a fresh, modern touch to bouquets.
- Gladiolus: Like dahlias, these grow from bulbs (corms) and offer tall, dramatic spikes that look incredible in tall arrangements.
By planting these together, you can walk out to your garden and harvest an entire bouquet in one go. We love the way 'Cafe au Lait' dahlias look when paired with the dark, moody foliage of a 'Black Knight' scabiosa or the airy stems of frosted explosion grass.
Key Takeaway: A cutting garden is most successful when you have a mix of "thrillers" (dahlias), "fillers" (cosmos or ammi), and "spillers" or foliage (eucalyptus or grasses).
Conclusion
Gardening is a journey of discovery, and finding the perfect partners for your dahlias is part of the fun. If you want even more pairing ideas, see our What Can You Plant With Dahlias? guide. Whether you choose the airy grace of cosmos, the functional protection of nasturtiums, or the steady structure of perennial salvia, companion planting helps you create a more resilient and beautiful space. By focusing on plants that share the same love for sun and well-drained soil, you set your garden up for success from the very first day.
At Longfield Gardens, our goal is to help you feel confident in your garden, and our 100% Guarantee backs every order. While every yard has its own unique soil and weather, these simple pairings are a great place to start. Remember to give your plants enough space to breathe, water them deeply, and enjoy the incredible transformation of your garden as it moves into the peak of summer.
- Start with a mix of heights to hide bare stems and add depth.
- Incorporate herbs to attract beneficial insects and deter pests naturally.
- Plan for color—choose a palette that makes you feel happy every time you look out the window.
- Respect spacing to ensure all your plants have the airflow they need to thrive.
The most important step is simply to get outside and start planting. With a little planning and the right neighbors, your dahlias will shine brighter than ever this season.
FAQ
Can I plant dahlias in the same bed as my roses?
Yes, you can plant dahlias near roses, provided both get enough sun and the roses aren't so large that they shade out the dahlias. Both plants are heavy feeders and appreciate rich, well-drained soil. Just ensure there is enough space between them so you can easily prune your roses and dig up your dahlia tubers if necessary.
Will companion plants steal all the nutrients from my dahlias?
Dahlias are very hungry plants, so it is important to provide enough fertilizer for everyone. If you plant low-growing annuals like alyssum, they won't compete much. However, if you plant large, aggressive perennials, you should increase your feeding and watering schedule to make sure your dahlias still get what they need to produce large blooms.
What are the best plants to hide the "bare legs" of tall dahlias?
Low-to-medium height plants are best for this. Sweet alyssum, dusty miller, and shorter varieties of zinnias or marigolds work perfectly. These plants create a lush "skirt" around the base of the dahlia, hiding the stems and keeping the soil cooler and more moist.
Do I need to worry about companion plants when digging up tubers in the fall?
If you live in a cold climate where you must lift your dahlia tubers for winter, keep this in mind when planting. It is easier if your companions are annuals that you can simply pull out at the end of the season. If you use perennials, plant them at least 18 inches away from the dahlia's center so you don't damage the perennial's roots when you dig up the tubers.