Best Companion Plants for Dahlias | The Perfect Cut Garden

Few things are cheerier than a big patch of fresh dahlias. But these cut flowers look even better when grown alongside the right co-stars. 

Planting other flowers in your dahlia bed will add visual appeal and attract more pollinators. Meanwhile, growing certain herbs could help protect your dahlias from annoying pests.

No matter your goal, choosing companion plants for dahlias is about more than just what looks good. In this article, you’ll learn which plants I like to grow with my dahlias and the various benefits these partnerships can create. 

What Is Companion Planting?

Companion planting is an age-old method of combining different plant species in a single bed to benefit the garden at large. 

Perhaps the most famous example of companion planting is the Three Sisters method. The ‘sisters’ in question are corn, squash, and beans.

When planted together, the corn provides a tall structure for the beans to climb while the squash spreads along the ground and keeps the soil cool and moist. The beans benefit both partners by stabilizing the corn stalks and fixing nitrogen into the soil.

Many gardeners would consider the Three Sisters method to be a perfect example of companion planting with vegetables. There are also plenty of ways you can utilize this strategy in your ornamental beds and landscaping.

Benefits of Companion Planting with Dahlias

The main goal of companion planting is to create some sort of beneficial relationship between the plants in your garden. Here are the biggest benefits that can be achieved by companion planting with dahlias:

Pest Control

Pest control is an extremely common motivation behind companion planting. Some plant species release chemicals that naturally deter insects and other wildlife. Growing these varieties near plants that frequently fall victim to pest damage is a great way to keep your garden safe.

Dahlias are very attractive to garden pests and can be frustrating to grow if you don’t have an effective defense strategy. While dahlias certainly won’t keep pests out of our garden, you can use other plant species to keep unwanted visitors at bay.

All-Season Color

Dahlias typically bloom from mid-summer to the first frost. No matter how much you enjoy the flowers when they finally appear, a bed made up entirely of dahlias has little to offer during the first half of the growing season.

Planting flowers that bloom earlier in the year alongside your dahlias will add visual variety and longevity to your garden beds. It will also attract new pollinators to the area that would otherwise look elsewhere for their springtime meals.

More Pollinators

Speaking of pollinators, you need to grow a large number of flowering plants if you want to attract beneficial insects, hummingbirds, and more to your garden. Dahlias themselves are favorites of many pollinators but it never hurts to add more variety.

More Pollinators

Better Design

A deceptively obvious benefit of companion planting with dahlias and other ornamentals is that it makes your garden look better. Incorporating many different plant species ensures your landscape has a wide range of colors, textures, sizes, and growth habits!

Best Companion Plants for Dahlias

You can grow any number of plants next to each other but that doesn’t make them good partners. In my experience, the best companion plants for dahlias tend to be those that bloom earlier in the year or that keep pests away.

Companion planting can also simply be a way to add diversity to your flower bed. In addition to choosing flowers you like the look of, be sure to take into consideration each plant’s ideal growing environment. I find that dahlias grow best in moderate temperatures, moist soil, and full sun. Suitable partners will need to thrive in the same conditions.

Remember that many dahlias get quite tall — some even need support to keep from toppling over. Growing a number of shorter flowering plants will give your garden a lush appearance and disguise the dahlias’ leggy stems.

Now that I’ve gone over what qualities plants need to qualify as good growing partners for dahlias, let’s get into the plants themselves:

Vegetables and Herbs

Onion and Garlic: Alliums like onions, garlic, shallots, and chives are some of the only vegetable crops worth planting next to dahlias. You can easily plant allium bulbs alongside your Dahlia tubers.

Dahlias are particularly prone to aphids. Members of the allium family release a chemical compound that prevents nearby aphids from ‘sniffing out’ the vulnerable dahlias.

Cilantro: This edible herb grows wonderfully in the same soil and sun conditions as dahlias. Cilantro is also routinely used for natural pest control, although it’s debated whether this effect is due to the cilantro itself or the beneficial insects that it draws in with its flowers.

Mint: Mint-based oils are commonly used in natural bug repellents. Growing this herb in your garden could have a similar effect on aphids and other unwanted visitors.

The biggest thing to keep in mind before planting mint is its tendency to spread. Mint is very hard to contain in most garden beds, so you’re best off keeping it in a container or using sturdy landscape borders. Perfect if you plan to grow your dahlias in containers too.

Anise: Anise is an attractive, flowering shrub that draws in a variety of beneficial insects with its strong aroma, including predatory wasps. Predatory wasps prey on aphids and other pests that target dahlias. You can also save the dried seeds for use in the kitchen.

Flowering Annuals and Perennials

Cosmos: These annual flowers tolerate a variety of soil conditions and won’t compete with your dahlias for moisture and other resources. Plus, both flowers make excellent cut bouquets.

Since cosmos and dahlias tend to have similar growth habits, it’s a good idea to grow different colors of each. This will add visual texture and variety to your cut flower bed.

Aster: Belonging to the same family as dahlias, asters will attract all types of pollinators to your garden. I suggest planting shorter asters around your dahlias for a tasteful blend of varying heights and colors.

Coneflower: Dahlias and Coneflowers have practically identical needs, making them excellent companions in the garden. 

Pollinators visit coneflowers frequently during the summer and their seed heads provide a food source for smaller birds in wintertime. Since coneflowers are hardy perennials, they’ll keep the garden populated even when dahlias are out of season.

Globe Thistle: While the word ‘thistle’ often brings to mind nasty weeds, the globe thistle is a gorgeous ornamental perennial. The puffball-shaped flowers offer great contrast against many types of dahlias.

As the name implies, this plant has thorny foliage that deters rabbits, deer, and other grazers. Butterflies and other pollinators, however, love the purple blossoms.

Dianthus: A garden filled with dahlias and dianthus is apt to look like something out of a storybook. You can plant a thick bed of dianthus in front of your taller dahlias or intermix the two.

Geranium: Like dahlias, garden geraniums (Pelargonium x hortorum) enjoy damp soil and full or partial sun. You can grow both flowers as perennials in USDA Zones 9 and warmer. In cooler climates, geraniums are commonly planted as annuals.

Geraniums can tolerate less sun than dahlias, so there’s no need to worry about the latter outgrowing the former and shading them out. Some pests will also be more attracted to geraniums, leading them to leave your precious dahlias alone.

dahlias with geraniums

Black-Eyed Susan: Black-eyed Susan is a North American native often grown for the pollinators it attracts. This perennial has a similar growth habit to most dahlias and will blend right into an existing flower bed.

Nasturtium: Nasturtiums are edible plants that produce vibrant flowers in shades of yellow, orange, and red. Despite these assets, nasturtiums are most commonly used in companion planting because aphids LOVE them. Growing nasturtium nearby will distract aphids that would otherwise feed on your dahlias. 

There are both vining and bushy nasturtiums on the market. For the best results, I recommend planting bushy varieties near dahlias. 

Sweet Alyssum: This is one of the only plants I recommend using as a ground cover around dahlias. Sweet Alyssum is beautiful and low-maintenance. It’s also drought-tolerant, so it’s unlikely to steal moisture away from your dahlia tubers.

Planting a dense layer of sweet alyssum at the base of your dahlias will keep the soil cool and moist throughout the summer months. There’s also no denying that these dainty white blossoms look great next to more colorful companions!

Petunia: Petunias are another potential groundcover plant suitable for growing with dahlias. I recommend arranging your petunia plants as a border that carries along the front of the bed. The petunias will gradually spread along the ground and their tubular flowers will contrast nicely against the dahlias.

dahlias with petunias

Marigold: Marigolds’ ability to fend off garden pests may be overstated but these flowers are still beautiful and easy to grow. I find that marigolds make excellent filler around larger dahlia specimens. 

Peony: Peonies and dahlias have similar care needs and can easily be grown next to each other. This pairing is great because peonies usually bloom before the dahlia season is in full swing.

Shrubs

Rose: This somewhat unusual combination is actually quite stunning when done correctly! More structured rose bushes contrast nicely against clusters of dahlias. And you can easily switch up the design from year to year with new tubers.

My advice is to choose dahlias and roses that share some characteristics in common — i.e., height, color palette, etc. These plants already have very different growth habits and you don’t want too much contrast in one bed.

Butterfly Bush: The unkempt nature of your average butterfly bush is complementary to dahlias and other members of the aster family. You’ll see plenty of interesting pollinators in the garden — not just butterflies — and extra flowers can be used in bouquets. 

Daylily: While not really a shrub, the daylily is a great candidate for adding structure in and around your dahlia beds. There are so many unique colors and patterns to choose from, including bright shades that rival those of dahlias. Daylilies typically remain much shorter than dahlias, so plant them in the front for the best effect.

Bad Companion Plants for Dahlias

Though dahlias attract many beneficial insects to the garden, they also draw in countless pests. This means that most vegetable and fruit crops shouldn’t be planted in the same general area as dahlias.

Avoid planting aggressive vines too close to your dahlias. There’s a good chance the vines will try to climb the dahlia stems, which can seriously damage the flowers.

Grasses also make bad companions in most cases. Spreading grasses will compete with the dahlias for water and other resources. Over time, the grass may choke out the tubers completely. I only recommend planting clump-forming grasses near dahlias for this reason.

For more companion planting ideas for flowers, here’s a link to Companion Plants for Coneflowers that you may enjoy.

Citations

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.