What Can You Plant With Dahlias

Table of Contents

1. Introduction
2. Understanding What Dahlias Need
3. Why Use Companion Plants?
4. Best Annual Flowers to Plant With Dahlias
5. Perennial Partners for a Permanent Display
6. Herbs That Help Your Dahlias Thrive
7. Designing With Color and Texture
8. Practical Tips for Success
9. Companion Planting in Containers
10. Managing the Season Transition
11. Summary of Top Companions
12. Conclusion
13. FAQ

Introduction

There is nothing quite like the excitement of seeing the first dahlia buds finally start to crack open in mid-summer. These plants are the undisputed stars of the late-season garden, offering a variety of colors and shapes that few other flowers can match. At Longfield Gardens, we spend a lot of time in our trial garden seeing how different plants interact with one another to create the best possible display.

While dahlias are breathtaking on their own, they truly shine when paired with the right companions. Planting them alongside other flowers and herbs can help hide their leafy "legs," manage common garden pests, and ensure your garden is full of color from late spring until the first frost. This guide is for home gardeners who want to move beyond a simple row of tubers and create a lush, multi-layered garden bed. By choosing plants that share the same sun and soil needs, you can turn a single flower bed into a season-long masterpiece.

Understanding What Dahlias Need

Before choosing companions, it is helpful to look at what dahlias require to thrive. Dahlias are sun-loving plants that need at least six to eight hours of direct light every day. They also prefer soil that drains well so their tubers do not sit in water. Because dahlias grow quickly and produce massive blooms, they are considered "heavy feeders." This means they need plenty of nutrients from the soil to reach their full potential. For a broader overview of dahlia care, see All About Dahlias.

When you select companions, you want plants that can keep up with these needs without competing too aggressively for resources. The best partners are those that enjoy the same sunny spots and regular watering schedule. You also want to consider the mature size of your dahlias. Some dinnerplate varieties can reach five feet tall, while border dahlias may only grow to 18 inches. Matching the height of the companion to the height of the dahlia is the first step toward a balanced garden design.

Why Use Companion Plants?

Companion planting is more than just a design choice. It is a practical way to solve common garden challenges. In a dahlia garden, companions serve three main purposes: aesthetic filling, pest management, and season extension.

Filling the Gaps

Dahlias often have a "top-heavy" appearance. The flowers are stunning, but the bottom third of the plant can look a bit sparse or leafy. Low-growing companions act as a living mulch. They cover the bare soil, keep the roots cool, and provide a lush green backdrop that makes the dahlia colors pop.

Natural Pest Management

Some plants naturally repel insects that like to snack on dahlia foliage, such as aphids or slugs. Other plants act as "trap crops," drawing pests away from your prized blooms and toward something less critical. Incorporating these plants into your bed creates a more balanced ecosystem where nature does some of the work for you.

Extending the Season

Dahlias are late bloomers. They usually don't start their big show until July or August. If you plant only dahlias, your garden bed might look a bit empty in May and June. By mixing in early-season annuals and perennials, you can enjoy a beautiful yard while you wait for the dahlias to take center stage.

Key Takeaway: The best companion plants for dahlias are those that share a love for full sun and rich soil while offering benefits like pest control or aesthetic filling.

Best Annual Flowers to Plant With Dahlias

Annuals are often the easiest companions to work with because they have a similar lifecycle to dahlias. You can plant them at the same time and enjoy them for a single season.

Cosmos

Cosmos are a classic pairing for dahlias. Both plants belong to the same botanical family, and they share a delicate, airy appearance. While dahlias provide the structure and heavy blooms, cosmos add movement and a "wildflower" feel. Varieties like 'Sensation Mix' or 'Purity' work well because they do not overwhelm the dahlias. They also attract pollinators like bees and butterflies, which help your entire garden thrive.

Sweet Alyssum

If you want to hide the base of your dahlia stalks, sweet alyssum is one of the best choices. This low-growing annual forms a thick carpet of tiny, honey-scented flowers. It stays close to the ground, so it won't compete with the dahlia for sunlight. We often use white alyssum in our trial garden because it looks like a soft cloud beneath the vibrant pinks and oranges of the dahlias.

Snapdragons

Snapdragons are excellent for early-season color. They often bloom in late spring and early summer, right when dahlias are still just leafy green mounds. As the weather heats up in mid-summer, snapdragons sometimes take a break, which is exactly when the dahlias begin to bloom. This "passing of the torch" ensures there is never a dull moment in your flower bed.

Zinnias

For a cutting garden that provides endless bouquets, zinnias are a must-have. They enjoy the same hot, sunny conditions as dahlias and come in a similar rainbow of colors. Planting zinnias and dahlias together gives you a variety of flower shapes—from the flat, daisy-like zinnia to the intricate pompon dahlia—making your indoor arrangements much more interesting. If you are building a dedicated bouquet bed, browse our dahlia collection.

Cleome (Spider Flower)

Cleome is a tall, dramatic annual that can hold its own next to even the largest dinnerplate dahlias. It has an architectural look with spindly "spider" legs and large flower heads. Because it grows tall, it is best planted behind or between dahlia plants. Cleome is also quite drought-tolerant once established, making it a low-maintenance partner.

Perennial Partners for a Permanent Display

If you prefer a garden that comes back year after year, perennials are a great investment. Since dahlias are usually lifted in the fall in colder zones, you should plant perennials in a way that leaves enough room for you to dig up your dahlia tubers without disturbing the perennial roots.

Salvia

Salvias are fantastic for drawing in hummingbirds and beneficial insects. Many varieties, like 'Victoria Blue' or 'May Night,' offer spiky purple or blue flowers. This vertical shape provides a wonderful contrast to the rounded, heavy blooms of a dahlia. Additionally, some gardeners find that the scent of salvia foliage helps deter deer and other nibbling visitors.

Yarrow (Achillea)

Yarrow is a hardy perennial that produces flat-topped flower clusters. This "landing pad" shape is a favorite for ladybugs and lacewings, which are natural predators of aphids. Since aphids are one of the most common dahlia pests, having yarrow nearby is like having a tiny security team for your garden. Yarrow is also very heat-tolerant and won't mind the full sun required for dahlias.

Verbena bonariensis

This plant is often called "tall verbena," and it is a favorite in professional landscape design. It features long, wiry stems topped with small purple flower clusters. Because the stems are so thin, you can see right through them. This allows you to plant them in front of dahlias without blocking the view. They add a sense of height and whimsy to the garden without taking up much physical space.

Phlox

Garden phlox offers large, fragrant flower heads in mid to late summer. It fills in the middle layer of the garden beautifully. If you choose a mildew-resistant variety, it will stay green and lush throughout the season. The sweet scent of phlox also adds a sensory dimension to the garden that dahlias lack, as most dahlias are not known for their fragrance.

Ornamental Grasses

Grasses like Pennisetum (fountain grass) provide a soft, flowing texture that balances the stiff stalks of dahlias. In the autumn, as dahlia colors become more intense, the seed heads of the grasses begin to shimmer in the late afternoon sun. This combination creates a sophisticated, professional look that lasts until the first hard frost. If you are planning your garden layout, dahlia planting and care tips can help you match heights and spacing.

Herbs That Help Your Dahlias Thrive

Mixing herbs into your flower beds is a smart way to maximize space and protect your plants. Many herbs have strong scents that confuse pests or attract helpful insects.

Nasturtiums

Nasturtiums are often used as a "trap crop." Aphids are naturally drawn to nasturtiums, so they will often congregate on these plants instead of your dahlias. Nasturtiums are also edible and come in beautiful trailing or mounding varieties. Planting them at the edge of a dahlia bed allows them to spill over the sides, softening the edges of the garden.

Artemisia

If slugs are a problem in your area, consider planting a border of Artemisia. This silver-foliage plant has a scent and texture that many slugs and snails find unappealing. It acts as a beautiful, shimmering barrier that protects the tender new shoots of your dahlias in the spring.

Cilantro and Anise

When these herbs are allowed to "bolt" and go to flower, they produce umbrella-shaped blooms called umbels. These flowers are magnets for predatory wasps—don't worry, these aren't the kind that sting humans! These tiny wasps are experts at hunting down garden pests. The delicate, feathery foliage of these herbs also provides a nice textural contrast to the broad leaves of the dahlia.

What to Do Next:

• Identify the sunniest spot in your yard for your dahlia bed.
• Choose 2–3 companions from the lists above based on your color preference.
• Space your dahlia tubers at least 18–24 inches apart to leave room for companions.
• Plant low-growing "fillers" like alyssum at the very front of the bed.
• Water everything deeply once a week to ensure all plants stay hydrated.

Designing With Color and Texture

When you are deciding what to plant with dahlias, think about the visual "vibe" you want to create. You can go for a harmonious look or a high-contrast look.

The Harmonious Garden

For a peaceful, unified look, choose companions that are in the same color family as your dahlias. For example, if you are growing the famous 'Cafe au Lait' dahlia, which has creamy, blush-pink tones, pair it with white snapdragons, silver dusty miller, and pale pink cosmos. This creates a soft, romantic atmosphere that is perfect for a cottage garden. If you want this variety for your own garden, see Dahlia Dinnerplate Cafe Au Lait.

The Vibrant Contrast Garden

If you love high energy, look for colors that are opposites on the color wheel. Pair bright orange dahlias with deep purple salvia or blue ornamental grasses. This makes the colors of both plants appear more vivid. Texture also plays a role here. Pair the large, smooth petals of a decorative dahlia with the spiky texture of cleome or the fine, needle-like leaves of cosmos.

Using Foliage for Balance

Don't forget about green and silver! Foliage plants like dusty miller or artemisia act as a "neutral" space for the eye to rest. In a garden filled with bright dahlia blooms, silver foliage can help separate the colors so they don't look cluttered. It also makes the garden look full and healthy even on days when fewer flowers are blooming.

Practical Tips for Success

Growing multiple types of plants in one bed requires a little bit of planning. Here are a few ways to ensure everyone gets along.

Watch the Spacing

Dahlias need good air circulation to stay healthy and avoid issues like powdery mildew. When you plant companions, make sure they aren't completely smothered by the dahlia leaves as the season progresses. Give each plant its own "bubble" of space. If a companion plant starts to lean too heavily on a dahlia, don't be afraid to give it a light trim.

Feeding and Watering

Because you are growing "hungry" dahlias alongside other plants, you may need to provide a little extra fertilizer. We recommend using a balanced flower fertilizer throughout the growing season. When watering, try to water at the base of the plants rather than over the leaves. This keeps the foliage dry and the roots hydrated. For timing, shipping, and zone guidance, check Shipping Information.

Staking and Support

Tall dahlias usually need stakes to keep them from falling over under the weight of their blooms. It is best to put your stakes in the ground at the same time you plant your tubers. This prevents you from accidentally poking a stake through a companion plant's roots later in the summer. Once the dahlias are tied to their stakes, your companions will have more room to spread out at the base.

Companion Planting in Containers

You don't need a huge backyard to enjoy this gardening style. Many dahlias, especially dwarf and border varieties, grow perfectly in pots. When planting in containers, use the "Thriller, Filler, Spiller" method. If you want a fuller walkthrough of container growing, read Can You Grow Dahlias in a Container?.

• The Thriller: A beautiful dahlia variety serves as the tall, focal point of the pot.
• The Filler: Add a mid-sized plant like dusty miller or a small salvia to fill in the space around the dahlia's middle.
• The Spiller: Use a trailing plant like sweet alyssum or nasturtiums to spill over the edges of the container.

In a pot, plants are closer together than in the ground, so keep a close eye on watering. Containers dry out much faster than garden beds, especially in the heat of summer.

Key Takeaway: Success with dahlia companions comes down to matching the right height and making sure every plant has enough space to breathe.

Managing the Season Transition

One of the most rewarding parts of gardening is watching the landscape change. In the spring, your companions like snapdragons and alyssum will be the stars. As the summer heat arrives, these might fade slightly, but your dahlias will start to stretch toward the sky.

By the time September rolls around, your dahlias will be at their peak. Many of your companions, like ornamental grasses and salvias, will also be looking their best. This creates a spectacular autumn finale that lasts until the first frost hits. Once the frost blackens the dahlia foliage, it is time to cut them back and lift the tubers for winter storage (in colder zones), leaving your perennials to go dormant until next year. If you are planning around your local weather, our hardiness zone guide can help.

Summary of Top Companions

Conclusion

Gardening is a journey of discovery, and finding the perfect partners for your dahlias is part of the fun. Whether you choose the airy charm of cosmos, the protective nature of nasturtiums, or the steady beauty of perennial salvias, your dahlias will benefit from the company. At Longfield Gardens, we believe that every yard has the potential to be a masterpiece when you focus on the simple basics of sun, soil, and spacing. For more dahlia ideas, start with All About Dahlias.

As you plan your garden this year, remember that there is no single "right" way to design. Start with a few plants you love, watch how they grow together, and don't be afraid to try something new next season. With a little bit of planning, you can create a dahlia bed that is vibrant, healthy, and full of life from the first green shoot of spring to the final bloom of autumn.

Key Takeaway: Using companion plants creates a healthier garden ecosystem and a more beautiful, layered look that lasts all season long.

FAQ

What should I not plant with dahlias?

Avoid planting dahlias near aggressive, spreading groundcovers or very large shrubs that will compete for root space and nutrients. You should also avoid plants that require a lot of shade, as the conditions needed to keep a dahlia happy will be too bright for shade-loving species.

Do dahlias grow well with roses?

Yes, dahlias and roses can be great companions because they both love full sun and rich, well-drained soil. Since roses often have their biggest bloom in early summer and dahlias peak in late summer, planting them together ensures a continuous supply of flowers for your garden and vases.

Can I plant herbs in my dahlia bed?

Absolutely. Herbs like rosemary, sage, and thyme can be planted at the edges of a dahlia bed. Their strong scents can help deter some pests, and they enjoy the sunny conditions. Just ensure the herbs don't get completely shaded out by the tall dahlia foliage as the season progresses.

Will companion plants take away nutrients from my dahlias?

Dahlias are heavy feeders, so it is important to provide enough fertilizer for all the plants in the bed. If you use a balanced flower fertilizer and ensure your soil is rich in organic matter, there should be plenty of nutrients to go around for both the dahlias and their companions.