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Specific varieties:
- ‘Sensation’ series
- ‘Little Bunny’
- ‘Hameln’
- ‘Powis Castle’
- ‘Cafe au Lait’
- ‘Kelvin Floodlight’
Subcategories:
- dinnerplate varieties / dinnerplate dahlias
- pompons
- smaller marigolds
- ornamental grasses
- cutting garden
Broad plant categories:
- dahlias
- cosmos
- zinnias
- Sweet Alyssum
- snapdragons
- salvia
- agastache
- Verbena bonariensis
- yarrow
- Pennisetum
- nasturtiums
- Artemisia
- anise
- cilantro
- alliums
- peonies
- eucalyptus
- Dusty Miller
- Ammi majus
- roses
- lavender
- mint
- ivy
Educational topics:
- full sun
- well-drained soil
- drainage
- rich soil
- hardiness zones
- planting and spacing
- staking and supports
- container planting
- watering
- fertilizing
- deadheading
- cutting garden
- pest control
- succession planting
- color theory
-->Introduction
Dahlia season is one of the most exciting times for any home gardener. When these spectacular blooms finally open in mid-to-late summer, they bring a level of color and drama that few other plants can match. Whether you love the massive blooms of dinnerplate dahlias or the intricate patterns of pompons, dahlias are the true stars of the sunny border. At Longfield Gardens, we enjoy helping you find the perfect partners to make these garden celebrities shine even brighter.
Choosing the right companions for your dahlias is about more than just picking pretty colors. It is an opportunity to create a garden that looks full and vibrant from late spring through the first frost. The right neighbors can help support heavy dahlia stems, hide the "bare legs" of taller varieties, and even help manage common garden pests. We want to make sure your garden feels like a cohesive, thriving space where every plant has room to flourish.
This guide will help you select the best flowers, herbs, and grasses to plant alongside your dahlias. We will cover plants that share the same love for sun and well-drained soil, as well as those that provide a beautiful contrast in texture and form. By the end of this article, you will have a clear plan for a professional-looking garden bed that celebrates the beauty of the dahlia.
The key to a successful mixed garden is matching plants with similar needs while creating a diverse tapestry of heights and textures.
Understanding the Needs of Dahlias
Before choosing companion plants, it is helpful to remember what makes a dahlia happy. Most dahlias thrive in full sun, which means they need at least six to eight hours of direct sunlight each day. They also prefer soil that is rich in organic matter and drains well. In the gardening world, "drainage" simply means how fast water leaves the soil. Dahlias do not like to sit in soggy ground, so their companions should also enjoy these same conditions.
Dahlias are also known as heavy feeders. They use a lot of energy to produce those large, complex flowers. When you choose neighbors for them, you want plants that will not aggressively steal all the nutrients and water. We recommend choosing well-behaved perennials and annuals that play nicely with others.
Timing is another important factor. Dahlias are planted in the spring once the soil has warmed up, but they often do not start their big show until July or August. Finding plants that bloom in the early summer can help bridge the gap so your garden stays colorful all season long.
Key Takeaway: Successful companion planting starts by matching plants that share a love for full sun, rich soil, and excellent drainage.
Best Annual Flowers for Dahlia Companions
Annuals are fantastic companions because they grow quickly and can be easily tucked into the spaces between your dahlia tubers. Since many annuals have a long blooming season, they provide a steady backdrop for the changing stages of your dahlias.
Cosmos
Cosmos are perhaps the most classic partner for dahlias. They have delicate, feathery foliage that provides a wonderful texture contrast to the broad, heavy leaves of the dahlia. Because cosmos are light and airy, they do not block the sunlight from reaching the lower parts of your dahlia plants.
We suggest planting white or soft pink cosmos, like the 'Sensation' series, with bold-colored dahlias. The simple, daisy-like shape of the cosmos bloom makes the complex structure of a dahlia look even more impressive. Cosmos are also excellent for attracting pollinators, which is always a plus for a healthy garden.
Zinnias
If you want a garden that feels like a constant explosion of color, zinnias are the way to go. Like dahlias, zinnias love the heat of summer and come in almost every color imaginable. They have similar watering and light requirements, making them very easy to grow in the same bed.
Try pairing shorter, mounding zinnia varieties with tall dinnerplate dahlias. The zinnias will fill in the front of the border while the dahlias provide the height in the back. Because both flowers make excellent stems for cutting, this combination will give you an endless supply of bouquets for your home.
Sweet Alyssum
One common challenge with tall dahlias is that the bottom of the plant can look a bit sparse as the season progresses. This is where Sweet Alyssum shines. This low-growing, carpet-like flower creates a beautiful "living mulch" at the base of your dahlias.
Sweet Alyssum stays close to the ground and produces clusters of tiny, honey-scented flowers. It helps keep the soil cool and suppresses weeds without competing for the dahlia’s space. White alyssum provides a clean, bright edge that makes the vibrant colors of the dahlias pop.
Snapdragons
Snapdragons are perfect for providing early-season interest. They often start blooming well before the dahlias are ready to flower. By the time the dahlias are reaching their full height in mid-summer, the snapdragons provide a lovely vertical accent at a medium height. They come in a wide range of colors, allowing you to create sophisticated color gradients in your garden beds.
What to do next:
- Identify the sunniest spot in your garden for your dahlia bed.
- Sketch a simple plan with taller dahlias in the back and shorter annuals in the front.
- Check your soil to ensure it is loose and doesn't hold too much water.
- Select a color palette that makes you happy, whether it is monochromatic or a rainbow of hues.
Perennial Partners That Return Every Year
Perennials are the backbone of the garden. Once established, they come back year after year, providing a reliable structure for your seasonal dahlia plantings.
Salvia and Agastache
Both Salvia and Agastache (often called Hyssop) are excellent companions because they offer a completely different flower shape. While dahlias are often round and full, Salvia and Agastache produce tall, slender spikes of flowers. This contrast in form is very pleasing to the eye.
These plants are also magnets for hummingbirds and butterflies. Having these visitors in your garden adds a sense of life and movement. Most varieties of Salvia are quite hardy and can handle the same sunny, well-drained spots where dahlias thrive. Blue and purple varieties of Salvia look stunning next to orange or yellow dahlias.
Verbena bonariensis
This plant is a favorite among garden designers. It produces tall, wiry stems with clusters of tiny purple flowers at the top. Because the stems are so thin, you can see right through them. This allows you to plant Verbena bonariensis in front of or among your dahlias without hiding them. It adds a "cloud" of purple that seems to float throughout the garden, tying different sections together.
Yarrow (Achillea)
Yarrow is a tough, reliable perennial that features flat-topped flower clusters and fern-like foliage. The horizontal shape of the yarrow flowers provides a nice resting spot for the eye amidst the vertical energy of the dahlias. Yarrow is very drought-tolerant once established, so it will not mind if the dahlias are hogging a bit of the water.
Ornamental Grasses
While not flowers in the traditional sense, ornamental grasses like Pennisetum (Fountain Grass) are incredible companions. They add movement, sound, and a soft texture that balances the heavy, static look of dahlia blooms. A smaller variety like 'Little Bunny' or 'Hameln' stays compact and looks beautiful tucked around the base of a large dahlia plant.
Key Takeaway: Use perennials with spike-shaped flowers or fine-textured foliage to create a professional, layered look in your dahlia garden.
Using Herbs for Beauty and Pest Control
Many gardeners are surprised to learn that common herbs make some of the best companions for dahlias. Herbs are often very fragrant and can help deter some of the pests that might otherwise bother your prize flowers.
Nasturtiums
Nasturtiums are a dual-purpose companion. They are beautiful, with lily-pad-shaped leaves and bright, edible flowers in shades of orange, yellow, and red. They are also famous for being "trap crops." This means they often attract aphids and other small pests away from your dahlias.
If you notice aphids on your nasturtiums, you can simply remove the affected leaves and dispose of them, leaving your dahlias clean. Mounding varieties of nasturtiums stay tidy and look great spilling over the edge of a garden bed or container.
Artemisia
Artemisia, such as the 'Powis Castle' variety, is grown for its stunning silvery-gray foliage. It has a scent that many garden pests, including slugs and snails, find unappealing. Since slugs are one of the few things that can really slow down a young dahlia plant, planting a border of Artemisia can be a helpful, natural way to protect your garden. The silver leaves also look sophisticated when paired with white or pastel-colored dahlias like 'Cafe au Lait'.
Anise and Cilantro
When these herbs are allowed to go to flower, they produce delicate, umbrella-shaped clusters of tiny blooms. These flowers attract predatory insects, such as lacewings and tiny wasps, which eat the pests that commonly bother dahlias. Anise has a sweet, licorice-like scent that adds another layer of enjoyment to your garden walks.
Color Theory for Stunning Combinations
When you are deciding what flowers grow well with dahlias, thinking about color can help you achieve a high-end look. You do not need to be an artist to use simple color rules.
Complementary Colors
Complementary colors are opposites on the color wheel, such as purple and yellow or blue and orange. These pairings create high contrast and make both colors appear more vibrant. Try planting deep purple Salvia next to a bright yellow dahlia like 'Kelvin Floodlight'. The result is energetic and eye-catching.
Analogous Colors
Analogous colors are next to each other on the color wheel, such as red, orange, and yellow. This creates a warm, harmonious look that feels like a sunset. Pairing a peach-colored dahlia with orange zinnias and yellow marigolds creates a glowing, cohesive garden bed.
The Power of White
White flowers act as a "buffer" in the garden. If you have two colors that seem to clash, adding a white companion plant like Sweet Alyssum or White Cosmos can help them get along. White also makes the garden feel fresh and bright, especially during the hot "dog days" of summer.
Planning for Height and Spacing
One of the most important things we tell gardeners at Longfield Gardens is to pay attention to spacing. Dahlias need "elbow room." Good air circulation is vital for keeping the foliage healthy and preventing mildew.
When planting companions, follow these general rules for height:
- The Back Row: Use tall dahlias (4 feet or taller) or tall perennials like Verbena bonariensis and tall ornamental grasses.
- The Middle Row: Use medium-height dahlias, zinnias, cosmos, and Salvia.
- The Front Row: Use low-growing companions like Sweet Alyssum, Nasturtiums, and smaller marigolds.
Make sure you leave enough space between the dahlia tuber and its neighbor. A good rule of thumb is to keep smaller companions at least 12 inches away from the main stem of the dahlia. This ensures everyone gets enough light and nutrients.
What to do next:
- Check the mature height of each plant on the tag or our website before planting.
- Ensure the tallest plants are on the north side of the bed so they do not shade the shorter ones.
- Leave paths or small gaps so you can reach in to deadhead your dahlias without stepping on their companions.
- Install stakes or supports for your dahlias early in the season so you don't disturb the companions later.
Growing Dahlias and Companions in Containers
If you have a small patio or balcony, you can still enjoy beautiful dahlia combinations. Many dahlias grow perfectly well in large pots. When choosing companions for a container, you are looking for plants that can share a limited amount of soil.
A classic "thriller, filler, spiller" arrangement works wonders:
- Thriller (The star): A mid-sized dahlia variety.
- Filler (The middle): A compact zinnia or a small bunch of Salvia.
- Spiller (The edge): Trailing Nasturtiums or Sweet Alyssum that hangs over the side of the pot.
In containers, plants dry out faster than they do in the ground. Be sure to water consistently. We recommend checking the soil daily during the heat of summer. If the top inch of soil feels dry, it is time to give them a deep drink.
Managing the Early Season Bloom Gap
Since dahlias are often planted in late spring and take several weeks to begin blooming, the garden can look a bit "green" in June. You can solve this by planting early-summer stars that will be finishing their show just as the dahlias start theirs.
Alliums are a fantastic choice for this. These ornamental onions produce purple globes on tall stems in late spring. By the time the dahlia foliage is getting large, the allium flowers are fading, and their leaves can be hidden by the growing dahlias. Note that we do not ship allium bulbs to Idaho due to state agricultural restrictions, but for most other regions, they are a great addition.
Peonies and Snapdragons are also excellent for early color. They provide beauty and fragrance while the dahlias are still gathering their strength for the big summer finale.
Key Takeaway: Mix early and late-blooming plants to ensure your garden is a source of joy from the moment spring ends until the first frost of autumn.
Caring for Your Mixed Garden Bed
Maintaining a garden with many different types of flowers is very rewarding, but it does require a little bit of regular attention. The good news is that these tasks are simple and can be a relaxing part of your routine.
Watering Correctly
The best way to water most flowers is "deep and infrequent." Instead of a light sprinkle every day, give the garden a thorough soaking a couple of times a week. This encourages the roots of both the dahlias and their companions to grow deep into the soil. Try to water the base of the plants rather than the leaves to keep everything healthy.
Feeding Your Plants
Because you have many plants growing together, they will be hungry. A balanced, water-soluble fertilizer can be applied every few weeks throughout the growing season. Follow the instructions on the label to ensure you are giving them the right amount.
Deadheading
"Deadheading" is just a fancy word for cutting off faded flowers. For both dahlias and companions like zinnias and cosmos, removing the old blooms tells the plant to keep making new ones. This simple step can extend your blooming season by several weeks.
Creating a Cutting Garden with Companions
Many people grow dahlias specifically for bouquets. If this is your goal, your companion choices should include flowers that look great in a vase.
Consider adding:
- Eucalyptus or Dusty Miller: For beautiful, silvery foliage that acts as a "filler" in bouquets.
- Snapdragons: For height and a different line in the arrangement.
- Ammi majus (False Queen Anne's Lace): For a delicate, lacy look that softens the bold appearance of dahlias.
When you harvest your flowers, the dahlia will respond by branching out and producing even more blooms. It is a win-win for you and the plant.
Conclusion
Creating a garden where dahlias grow alongside perfect companions is one of the most rewarding projects a gardener can undertake. By choosing plants that share the same love for sun and well-drained soil, you create a healthy environment where every flower can shine. Whether you are looking for the pest-deterring properties of herbs, the airy texture of ornamental grasses, or the vibrant color of annuals, there is a companion for every dahlia.
- Start with the basics: sun, drainage, and space.
- Mix different flower shapes like spikes, globes, and daisies for visual interest.
- Use low-growing plants to hide the base of tall dahlias.
- Don't forget to include herbs for a fragrant and functional garden.
At Longfield Gardens, we want you to feel confident and excited about your garden. With a little planning and the right partners, your dahlias will be part of a stunning, season-long display that brings beauty to your home and neighborhood.
"A garden is most beautiful when it mimics the diversity of nature, bringing together different heights, textures, and colors in one happy community."
Order your favorites today and get ready for a summer filled with spectacular blooms!
FAQ
Do dahlias need a lot of space from their companion plants?
Yes, dahlias need good air circulation to stay healthy and prevent issues like powdery mildew. We recommend keeping smaller companion plants at least 12 inches away from the base of the dahlia. For larger perennials, ensure there is enough room for both plants to reach their full mature width without completely overlapping.
Can I plant roses and dahlias together?
You can plant them in the same garden, but they have slightly different needs. Roses are permanent shrubs, while dahlia tubers are often dug up in the fall in colder climates. If you plant them together, make sure the dahlias are far enough away that you can dig them up without disturbing the rose roots. Both love sun and rich soil, so they can be great aesthetic partners.
Which plants help keep slugs away from dahlias?
Slugs are attracted to the tender new growth of dahlias. Planting Artemisia (Wormwood) or Lavender nearby can help, as these plants have strong scents and textures that slugs generally avoid. You can also use a border of Sweet Alyssum, which provides a home for predatory insects that may help keep pest populations in check.
Are there any plants I should avoid planting with dahlias?
Avoid planting dahlias near "heavy drinkers" or aggressive spreaders like mint or certain types of ivy. You also want to avoid very large, thirsty trees or shrubs that will cast too much shade or steal all the moisture from the soil. Stick to well-behaved garden favorites that enjoy the same sunny, well-drained conditions as your dahlias.
