Choosing Companion Plants for Zinnias | Do’s and Don’ts

The practice of companion planting has been around for a very long time. But with more and more newcomers entering the world of home gardening, I’ve encountered many who don’t quite know where to start.

On the one hand, you can discover beneficial plant combinations just by experimenting. This is also a great way to learn what grows best in your garden and specific climate. 

For gardeners looking to plant as efficiently as possible, however, it’s better to stick with tried and true pairings. Zinnias are incredibly popular in companion planting and offer a great jumping-off point for beginners.

Below you’ll find some of my favorite companion plants for zinnias as well as a bit more info about this gardening practice and the benefits it can provide.

What Exactly Is Companion Planting?

We can often make our gardens more efficient by growing two or more plants that benefit each other. This practice is known as companion planting. Some potential benefits of companion planting include pest control, improved space utilization, and pollinator diversity.

I always point to the Three Sisters method as a prime example of companion planting in action. According to the Old Farmer’s Almanac, this agricultural technique was originally developed by several American Indian tribes. 

The Three Sisters method features corn, pole beans, and squash. Their roles are as follows:

• Corn grows tall and provides a supportive structure for the pole beans to climb.
• Pole beans help anchor the corn stalks against strong winds. The beans also perform something called ‘nitrogen fixation’, which takes nitrogen from the air and transfers it to the soil where other plant roots can absorb it.
• Squash shades the soil with its large leaves to prevent weed growth and moisture loss. Since the squash plants stay very close to the ground, they don’t compete with the corn or beans for sunlight or space.

You don’t need to be a gardening pro to realize how effective the above combination of plants can be. After all, there’s a reason this technique is still commonly used today.

Companion planting in your own garden might not be as harmonious as the Three Sisters method. However, it’s still worth exploring the ways you can use different plant combinations to your advantage!

Benefits of Companion Planting

There are countless potential benefits to effective companion planting and there’s no way for me to cover them all here. But you should still take a moment to learn about the most common benefits offered by Zinnias and their companions before moving on to the plant list in the next section.

Pest Control: One of the greatest benefits of companion planting is natural pest control. There are a few mechanisms that can be at play depending on the type of plants used.

Some plant species deter common pests because they produce strong fragrances or chemical substances. Growing such plants adjacent to fruit and vegetable crops is a common way to deter pests.

Many flowering plants attract predatory insects like wasps and hoverflies that prey on caterpillars and other crop-damaging pests. Purposefully growing plants that draw in these predators is a great way to limit local pest populations.

Companion plants may also be sacrificed in favor of more valuable plants (typically food crops). This is done by planting things that common pests really like in hopes that the insects will choose to feed on the ‘sacrifice’ rather than the nearby fruits or vegetables.

Saves Space: There are several plant combinations that actually increase the amount of usable space in the garden. A great example would be the beans climbing the corn stalks in the Three Sisters method.

I usually see this benefit utilized in food gardens. However, it’s also a great strategy for any gardener wanting to cram as many ornamental plants into their landscape as possible.

Attracts Pollinators: More pollinators are almost always a good thing for the garden. Not only do most of us enjoy seeing the busy bees, butterflies, and birds at work but pollination is also essential for many food crops.

Planting tons of attractive flowers signals to the local pollinators that your garden is open for business and sure to satisfy. The Chicago Botanic Garden recommends planting tall zinnias in shades like red or bright pink for the greatest draw.

Best Companion Plants for Zinnias

When it comes to companion planting with zinnias, the zinnias are rarely the star of the show. This is especially true when you combine flowers with edible crops like vegetables and herbs. The zinnias’ main purpose is to protect the food crops and ensure a good harvest.

But zinnias can also play a vital role in the ornamental garden — they’re one of my all-time favorite annuals. So I’ve included several of the best flowering companions for those scenarios as well.

Vegetables and Herbs

• Basil: Zinnias and basil work very well together because they both enjoy plenty of sunshine and moderately moist soil. This is a great combination for any cottage-inspired garden design. As for more tangible benefits, basil, and zinnias both offer natural pest control. Basil has a strong odor that some insects dislike. And each plant’s flowers are known to attract beneficial predatory insects to the garden. Consider planting both zinnia and basil near other edible crops for a host of benefits.

• Tomatoes: Tomatoes and basil are frequently planted together, so it only makes sense that zinnias would make good partners as well. Again, the zinnias will attract predatory insects and may even act as a trap crop for the tomatoes. (Any pests that opt to feed on the zinnias are less likely to go after your beloved Romas!) The zinnias will also draw in additional pollinators that will help the tomato plants produce more fruit.

• Brassicas: There are many vegetables that fall into the brassica family but it’s easiest to cover them all at once. Rest assured that you’ll enjoy the same benefits whether you’re growing cabbage, broccoli, cauliflower, kale, or another variety altogether. Interplanting zinnias among your brassicas is an effective way to deter pests (something vegetables in this family are infamous for attracting). A dense blanket of zinnias will also help keep the soil around the brassicas cool and prevent moisture loss.

• Cucumber: I like to place zinnias near my cucumbers because both plants thrive in identical growing conditions. Plus, the zinnia flowers catch the attention of local pollinators who, in turn, visit the cucumber blossoms. Another potential benefit of this combo is that zinnias sometimes attract ladybugs, lacewings, and other predators that specifically target pests that feed on cucumbers.

• Peppers: Like tomatoes, pepper plants benefit from the zinnias’ ability to attract pollinators and predatory insects. Surrounding your peppers with dwarf zinnias can also help retain moisture and keep the soil temperature low without interfering with sun exposure.

• Asparagus: Asparagus is easy to grow but needs several years to establish itself before the first harvest. I’ve found that growing zinnia in the same bed helps deter pests that would otherwise attack the asparagus. Zinnias are particularly great for this purpose because their root systems won’t disturb the asparagus crowns.

Annuals and Tender Perennials

• Dahlias: Many varieties of dahlias and zinnias are almost indistinguishable without an expert eye. This is no coincidence since both species belong to the aster family. The familial relationship also means that dahlias and zinnias enjoy similar environments. And they naturally go together since they share so many physical characteristics in common.

• Marigolds: Marigolds are another member of the aster family and can sometimes be mistaken for a type of zinnia (and vice-versa). You’ll often see marigolds planted among vegetable gardens in the same manner as zinnias to control pests and fill empty spaces.

Combining marigolds with zinnias is an easy and low-maintenance way to add extra variety to any flower bed.

• Dusty Miller: Also known as silver ragwort, this is an ornamental plant most commonly grown for its unique foliage. It also produces yellow flowers that look like very small daisies. In all honesty, the main reason I recommend dusty miller as a Zinnia companion is that the two just look good together. Plant dusty miller in front of your zinnia patch as bedding or combine both annuals in an outdoor container.

Hardy Perennials and Shrubs

• Salvia: Ornamental salvias are typically larger than zinnias and attract a wide variety of pollinators to the garden. I like to plant salvia behind annual beds containing zinnias and other flowers for a low-maintenance backdrop.
• Coneflowers: Coneflowers, including black-eyed Susan, are hardy perennials that grow well alongside zinnia and other fellow members of the aster family. These flowers are highly recommended for attracting native pollinators. If you leave the seed heads out through winter, they also provide a valuable food source for songbirds.

• Ornamental Grass: Ornamental grasses like purple fountain grass make excellent backdrops for annual beds of all kinds. There are many varieties that tolerate the same full sun and moist soil that zinnias crave.
• Clematis: You also can’t go wrong using zinnias to fill the space in front of a clematis vine. While clematis happily climbs up fences and trellises, they tend to have leggy bases. The zinnias will disguise the barren stems while keeping the soil around the clematis nice and cool.

Bad Companion Plants for Zinnias

For the best results, avoid plants that prefer dry conditions like lavender and rosemary. While these plants might flourish for a short time next to zinnias, you’ll eventually encounter moisture problems. Either the zinnias will be too dry or the companions will succumb to overwatering and fungal diseases.

Citations

• Old Farmer’s Almanac Three Sisters growing method
• Chicago Botanic Garden Zinnia benefits from the garden