Table of Contents
- Introduction
- Choosing the Best Companions for Your Dahlias
- Annual Flowers for Vibrant Color Combinations
- Perennials for Lasting Beauty
- Using Flowers for Natural Pest Control
- Creating a Sensory Experience: Fragrance and Texture
- Planning for Successional Blooms
- Designing with Dahlias: Height and Spacing
- Tips for Caring for a Mixed Garden Bed
- Companion Planting in Containers
- Plants to Avoid Near Dahlias
- Conclusion
- FAQ
Introduction
There is nothing quite like the excitement of seeing your first dahlia buds begin to swell in mid-summer. As these spectacular flowers start to open, they transform the garden into a sea of color that lasts until the first frost. At Longfield Gardens, we know that while dahlias are certainly the stars of the show, every star performs better with a great supporting cast.
Choosing the right companion plants for your dahlias is about more than just finding pretty colors that look good together. It is about creating a healthy, balanced ecosystem where plants help each other grow. This guide is for home gardeners who want to maximize their space, deter pests naturally, and enjoy a garden that looks full and vibrant from spring through autumn.
By matching dahlias with plants that share their love for sun and well-drained soil, you can create a professional-looking landscape right in your own backyard. Selecting the right flower companions ensures your garden stays healthy and beautiful throughout the entire growing season.
Choosing the Best Companions for Your Dahlias
Dahlias are incredibly versatile, but they do have specific needs. They are heavy feeders and love plenty of sunlight. When you are deciding what flowers can you plant with dahlias, the most important rule is to match the "roommates" to the environment.
We find that the most successful dahlia beds include a mix of annuals and perennials that do not compete too aggressively for nutrients. You want neighbors that are "well-behaved"—plants that stay in their own space and do not try to choke out the dahlia tubers.
Why Use Companion Plants?
Companion planting is an age-old gardening technique that serves several purposes. In a dahlia garden, companions can:
- Provide structural support: Taller, sturdier plants can help shield dahlias from wind.
- Deter pests: Certain flowers release scents that confuse or repel insects like aphids and beetles.
- Attract pollinators: Flowers like salvia and zinnias bring in bees and butterflies that help the whole garden thrive.
- Hide "ugly legs": As dahlia plants grow tall, the bottom stems can sometimes look a bit bare. Low-growing flowers act as a beautiful "skirt" to hide these stems.
- Extend the season: Dahlias usually start blooming in mid-to-late July. Planting early-season flowers nearby ensures your garden is colorful in May and June.
Key Takeaway: The best companion plants for dahlias are those that share the same sun and soil requirements without being invasive or overly competitive for water and food.
Annual Flowers for Vibrant Color Combinations
Annuals are often the easiest choice for dahlia companions because they have a similar lifecycle. Many annuals bloom at the same time as dahlias, allowing you to create stunning color palettes.
Zinnias
Zinnias and dahlias are a match made in gardening heaven. They both love full sun, rich soil, and regular watering. Because they come in almost every color of the rainbow, you can perfectly match your zinnias to your favorite dahlia varieties. Zinnias also attract hoverflies and ladybugs. These beneficial insects are natural predators of aphids, which often try to snack on dahlia leaves.
Cosmos
Cosmos are perhaps the most classic partner for dahlias. They have fine, feathery foliage that provides a soft, hazy backdrop for the broad leaves of the dahlia. Cosmos 'Purity' offers clean white flowers that make the bold colors of dinnerplate dahlias pop. These plants are also very attractive to pollinators, ensuring your garden is buzzing with life.
Cleome (Spider Flower)
Cleome is a tall annual that works well at the back of the border behind your dahlias. They provide a unique architectural shape with their "spider-like" blooms. Because they can reach four or five feet in height, they won't be hidden by even the tallest dahlia varieties.
Snapdragons
Snapdragons are excellent for adding vertical interest. They often bloom earlier than dahlias, providing color in the early summer while your dahlias are still putting on green growth. By the time the dahlias take over the spotlight, the snapdragons provide a sturdy, colorful base.
What to do next:
- Choose a color theme, such as "sunset tones" (oranges, reds, yellows) or "cool pastels" (whites, pinks, purples).
- Plant taller annuals like cleome at the back of the bed.
- Place mid-sized plants like zinnias and cosmos between your dahlia stakes.
- Use shorter flowers to fill in the front edge.
Perennials for Lasting Beauty
Perennials provide a permanent framework for your garden. Perennials create a garden that feels established and lush.
Salvia
Many types of salvia, especially the perennial varieties like 'May Night', are wonderful partners for dahlias. The upright spikes of purple or blue flowers contrast beautifully with the rounded shapes of dahlia blooms. Salvia is also a magnet for hummingbirds, which are a joy to watch in the garden.
Phlox
Garden phlox offers large clusters of scented flowers in mid-to-late summer. They enjoy the same rich, moist soil that dahlias crave. Planting phlox near your dahlias adds a layer of fragrance that dahlias themselves lack.
Ornamental Grasses
Grasses like Pennisetum (fountain grass) add movement and a soft texture that complements the heavy, solid look of dahlia plants. As the wind blows, the grasses sway, bringing the whole garden to life. They also look spectacular in the autumn as the dahlias reach their peak.
Achillea (Yarrow)
Yarrow features flat-topped flower clusters that provide a different geometric shape to the garden landscape. They are very hardy and can handle the summer heat just as well as dahlias. Yarrow also attracts predatory wasps that help keep garden pests in check.
Using Flowers for Natural Pest Control
One of the smartest ways to use companion plants is to let them do the "dirty work" of pest control for you. Some flowers are naturally gifted at keeping common dahlia enemies away.
Marigolds
Marigolds are famous for their ability to deter pests. They produce a scent that many garden insects find off-pitting. More importantly, certain types of marigolds release substances from their roots that help repel nematodes in the soil. They are low-growing and easy to tuck into the corners of your dahlia beds.
Nasturtiums
Nasturtiums are often used as a "trap crop." Aphids are naturally drawn to nasturtiums. By planting them a short distance away from your dahlias, you can lure the aphids away from your prized flowers. The leaves and flowers of nasturtiums are also edible, adding a peppery kick to summer salads.
Sweet Alyssum
This low-growing annual creates a carpet of tiny, honey-scented white flowers. We love using sweet alyssum as a living mulch. It covers the soil, keeping the roots of your dahlias cool and moist. It also attracts tiny beneficial wasps that eat the eggs of many common garden pests.
Artemisia
Plants in the artemisia family, such as 'Powis Castle', have silvery-gray foliage that looks stunning against dark-leaved dahlias. They also have a strong herbal scent that can help deter slugs and snails, which are notorious for nibbling on young dahlia shoots.
Creating a Sensory Experience: Fragrance and Texture
Dahlias are famous for their visual impact, but they generally lack scent. To create a truly immersive garden, you can plant perennials with fragrant flowers nearby to fill the air with perfume.
Nicotiana (Flowering Tobacco)
Nicotiana is a wonderful choice for scent, especially in the evening. As the sun goes down and the air cools, the perfume of nicotiana becomes much stronger. This makes your garden a pleasant place to sit after a long day. The star-shaped flowers look lovely tucked between larger dahlia plants.
Gardenias
In warmer climates (or in containers in the North), gardenias can be a luxurious companion. Their creamy white flowers and intense fragrance provide a sophisticated contrast to the bright, cheerful colors of dahlias. They both appreciate slightly acidic, well-drained soil.
Dusty Miller
For texture, it is hard to beat Dusty Miller. Its lacy, silver leaves are soft to the touch and provide a "neutral" backdrop that makes the colors of your dahlias seem even more vivid. It is a tough little plant that stays compact, making it a perfect edging flower.
Planning for Successional Blooms
A common challenge for dahlia growers is the "green gap"—the period in early summer when the plants are growing fast but haven't started blooming yet. You can solve this by planting early-season flowers in the same bed.
Peonies and Lilies
Peonies bloom in late spring and early summer. By the time their flowers fade, your dahlias are just beginning to take off. The bushy foliage of the peonies remains beautiful all season and provides a green backdrop for the dahlia flowers later on. Similarly, Oriental and Asiatic lilies provide a vertical burst of color in June and July just before the dahlias hit their stride.
Alliums
Planting allium bulbs in the fall will give you spectacular "globe" flowers in late spring. These tall, architectural plants die back just as the dahlias need more space. This is a great way to get double use out of the same patch of garden soil.
Key Takeaway: Successional planting ensures that as one flower finishes its show, another is ready to take its place. This keeps your garden looking intentionally designed throughout the year.
Designing with Dahlias: Height and Spacing
When you are deciding what flowers can you plant with dahlias, you must consider the final size of each plant. Dahlias vary wildly in size, from low-growing "border" dahlias to six-foot tall dinnerplate dahlias.
Layering Your Plants
Think of your garden bed like a class photo. You want the tallest plants in the back and the shortest ones in the front.
- Back Row: Tall dahlias, Canna lilies, Cleome, and tall Sunflowers.
- Middle Row: Medium dahlias, Zinnias, Salvia, and Phlox.
- Front Row: Border dahlias, Marigolds, Sweet Alyssum, and Nasturtiums.
The Importance of Airflow
While it is tempting to pack plants tightly for a full look, dahlias need good airflow to stay healthy. Crowded plants are more susceptible to powdery mildew. When planting companions, make sure there is enough space for air to circulate around the base of your dahlias. Getting the spacing right is one of those simple gardening rules that makes a huge difference in the long run.
Tips for Caring for a Mixed Garden Bed
Maintaining a garden with many different types of flowers requires a bit of planning. At Longfield Gardens, we recommend 8 Tips for Growing Better Dahlias to keep everyone happy.
Water Correctly, Not Constantly
Dahlias like consistent moisture, but they hate "wet feet." Most of their companions, like zinnias and salvia, feel the same way. The best approach is to water deeply once or twice a week, rather than giving them a light sprinkle every day. This encourages roots to grow deep into the soil.
Feed the Heavy Eaters
Dahlias are hungry plants. When you plant them with other flowers, there are even more mouths to feed. Use a balanced fertilizer throughout the growing season to ensure all your plants have the nutrients they need to produce those big, beautiful blooms.
Deadheading for More Blooms
To keep your garden looking fresh, make a habit of removing faded flowers. This process, called deadheading, tells the plant to stop making seeds and start making more flowers. This applies to your dahlias as well as companions like cosmos, zinnias, and marigolds. For a full guide, see How to Grow and Care for Dahlias.
Companion Planting in Containers
If you have a small patio or balcony, you can still enjoy dahlias in containers. Many smaller dahlia varieties, such as the "gallery" or "melody" series, grow perfectly in pots.
The Thriller, Filler, Spiller Method
This is a simple rule for creating beautiful containers:
- The Thriller: This is your centerpiece. Use a vibrant dahlia variety here.
- The Filler: These are mid-sized plants that surround the dahlia. Good choices include heliotrope or small zinnias.
- The Spiller: These plants hang over the edge of the pot. Trailing lobelia, bacopa, or nasturtiums work beautifully.
Using this method ensures your container looks full and professionally designed. Just remember that containers dry out faster than garden beds, so check the soil moisture daily during the heat of summer.
Plants to Avoid Near Dahlias
While many flowers are great neighbors, some just don't get along with dahlias. It is best to avoid:
- Aggressive Groundcovers: Plants like mint or certain types of ivy can quickly wrap around dahlia tubers and steal all the nutrients.
- Bog Plants: Flowers that love soaking wet soil, like Cannas (though they can be neighbors, they often want more water than a dahlia can handle in heavy soil) or Marsh Marigolds, are not a good fit because the dahlia tubers might rot.
- Desert Plants: Cacti and succulents need very little water and very different soil. If you give the dahlia what it needs, the succulent will likely suffer, and vice versa.
Conclusion
Dahlias are truly the crown jewels of the late-summer garden. By thoughtfully choosing what flowers can you plant with dahlias, you can create a garden that is not only beautiful but also resilient and healthy. Whether you choose zinnias for color, marigolds for pest control, or grasses for texture, your dahlias will appreciate the company.
Remember that gardening is a journey of discovery. Don't be afraid to try a new combination next season. At Longfield Gardens, we are here to help you every step of the way with high-quality bulbs and practical advice, backed by our 100% Quality Guarantee. We want your garden to be a place of joy and relaxation.
- Match plants with similar sun and water needs.
- Use a mix of heights to create depth and hide bare stems.
- Include "trap crops" like nasturtiums to manage pests naturally.
- Don't forget to leave room for airflow to prevent disease.
If you are still deciding on a palette, our Spring-Planted Bulbs By Color page can help.
"The most successful gardens aren't just collections of plants; they are communities where each flower helps its neighbor thrive."
We look forward to seeing your garden grow! If you ever have questions about your bulbs or need help planning your next flower bed, Contact Us and our team is always ready to support your gardening journey.
FAQ
Can I plant dahlias and roses together?
Yes, dahlias and roses can be excellent companions. They both love full sun and rich, well-drained soil. Because roses often have their biggest bloom in early summer and dahlias peak in late summer and fall, planting them together ensures your garden has a constant supply of flowers for months on end.
Will marigolds really protect my dahlias from pests?
Marigolds are very helpful for repelling certain pests like nematodes and aphids through their scent and root secretions. While they aren't a "magic shield" that prevents every bug, they are a fantastic part of an integrated pest management strategy that reduces the need for chemicals in your garden.
What is the best flower to hide the bottom of tall dahlia plants?
Sweet alyssum and Dusty Miller are two of the best choices for hiding "ugly legs" on tall dahlias. They stay low to the ground and create a dense, attractive carpet of foliage and flowers. This not only looks better but also helps keep the soil moist and cool for the dahlia roots.
Can I plant dahlias with vegetables?
Absolutely! Dahlias are a wonderful addition to a vegetable garden. They attract pollinators that are essential for crops like squash and cucumbers. Planting them near your veggies also provides you with easy access to cut flowers while you are harvesting your backyard produce.