7 Plants Never to Grow Next to Zinnias – For Spectacularly Vibrant, Long-Lasting and Joyful Blooms
Zinnias are pretty easy going, but there are some plants they just don't get along with
If you love a summer yard filled with colorful, easy-going blooms, zinnias have to be at the top of your planting list. These low-maintenance, cut-and-come-again flowers can bring beds and borders to life, but only if you avoid growing certain plants alongside them.
These popular annuals can be easily overwhelmed by hungry feeders, unruly ground huggers and voracious climbing plants. Stealing essential nutrients from the soil and shading out the sun, it’s well worth knowing how to grow zinnias with the right kind of companions, so you can ensure a successful and bold floral display.
We spoke to horticultural and garden experts to save you the heartbreak of a failed summer show and find out exactly which plant pairings to avoid – as well as ideas on the flower lookalikes to opt for instead.
1. Impatiens
Bright, breezy and easy to grow, impatiens – specifically Impatiens walleriana is one of the most popular summer annuals to go out and buy. Perfect for adding color to beds, you could be tempted to pair it with the equally vibrant zinnia but you would be disappointed.
‘This classic annual flower looks like it would be a great companion for zinnias, but the two need very different growing conditions,’ says Costa Farms Horticulturalist Justin Hancock.
‘Zinnias want a spot in all-day sun to thrive and bloom well; impatiens want protection from the blazing summer sun. Instead, look for SunPatiens hybrids. These plants get a bit bigger, but otherwise have a similar look. And they appreciate the same amount of sun as zinnias.’
Walmart have a wide selection of SunPatiens hybrids to choose from. We particularly like the dreamy Compact Blush Pink SunPatiens, from Walmart.
Shop Zinnia Growing Kit
2. Lavender
Successful planting combinations usually come down to one simple rule: plants thrive alongside neighbours that enjoy the same growing conditions. That’s why understanding where a plant naturally grows – from dry Mediterranean hillsides to fertile meadow borders – can make all the difference when planning a flower bed.
While soil pH and drainage can be adjusted with compost, grit, and organic matter, the simplest and most sustainable approach is still to choose plants suited to the conditions you already have.
Zinnias, for example, are relatively thirsty and hungry plants, appreciating regular moisture throughout summer. So although they look beautiful woven through relaxed cottage garden planting schemes, it’s worth checking that nearby plants won’t struggle with those conditions.
‘Lavender naturally prefers dry, lean soil, while zinnias enjoy richer, more consistently moist soil,’ says Carrie Spoonemore, Co-founder of Park Seed's app From Seed to Spoon.
If you love the romantic contrast of zinnias and lavender together, there are ways to make the pairing work more successfully. Look for lavender varieties that tolerate slightly wetter conditions, such as Lavandula angustifolia ‘Havana’, or swap lavender entirely for plants that deliver a similar soft haze of color without demanding dry soil, such as catmint.
One of the best alternatives is Nepeta subsessilis, or short-stalked catmint – a relaxed, clump-forming perennial with lavender-toned flower spikes that is far better adapted to moist soil and can even cope with part shade.
Catmint plants are available at Nature Hills.
3. Mint
Zinnias need sun, moist soil and good ventilation to thrive, and do not cope well with thuggish behaviour. Fast growing ground cover plants such as mint, Mentha spicata can quickly overwhelm these tender blooms.
‘Common mint grows aggressively and can compete for nutrients and space, especially in shared containers or tight beds,’ says Carrie Spoonemore.
More sympathetic, leafy beauties to grow, include common nasturtiums with their rounded, peppery green leaves, basil and parsley. All preferring in a moist, sunny spot, they are generally well behaved and won’t steal goodness from the soil or grow too quickly.
Justin Hancock is a Costa Farms horticulturist with over 25 years in the industry. A plant enthusiast and educator, he has a degree in horticultural science and has worked in garden centers and botanical gardens, as a garden designer, and in garden publishing (including at Better Homes and Gardens). He has experience gardening across the country, from Minnesota to Miami to Oregon. Justin is also co-host of the Costa Farms podcast Plant Rx.
Carrie Spoonemore, co-founder of Park Seed’s app 'From Seed to Spoon' has dedicated herself to empowering people to take control of their health and environment by growing their own food. Her journey alongside her husband, Dale Spoonemore, in creating a platform that demystifies gardening and promotes a healthier lifestyle, has made a significant impact on individuals around the globe
4. Cucumber
If you’re looking for colorful annuals to lure pollinators into a vegetable garden, zinnias are often one of the first flowers gardeners reach for. With their long flowering season and love of full sun, they seem like natural companions for productive crops, such as cucumbers. But despite sharing similar growing conditions, this pairing can create problems beneath the surface.
‘Zinnia and cucumbers have the same nutritional needs and as cucumbers are very heavy feeders, they will likely deplete the soil of the nutrients that will also help zinnias flourish,’ explains plant expert Katie Sunderlage. She also notes that ‘cucumbers also attract cucumber beetles and are affected by powdery mildew which both can cause problems for the zinnias planted in the same area.’
In small raised beds or compact kitchen gardens, this competition for nutrients can quickly leave zinnias looking lackluster, with fewer blooms and weaker growth as the season progresses. Shared susceptibility to fungal issues such as powdery mildew can make matters worse, particularly during warm, humid weather.
Instead, Katie recommends pairing zinnias with less demanding crops that still benefit from the pollinator boost these cheerful flowers provide.
‘They both require full sun and have the same watering needs, but enough nutrients will remain in the soil to help both thrive. Zinnia will also help attract essential pollinators to the zucchini and/or squash plants for high yields,’ she explains.
zucchini and squash also create a similarly abundant, cottage-garden-style look in vegetable plots, allowing zinnias to shine without forcing plants to compete quite so heavily for moisture and nutrients.
You can find lots of zucchini seed varieties at True Leaf Market.
5. Sunflower
If you are planning a cut flower garden chances are zinnias and sunflowers, Helianthus annus, will be at the top of your ‘to grow’ list, but before you get sowing and planting stop and think again.
Plant expert Katie, along with experienced flower farmers advise to keep them well apart. ‘It’s common to want to grow different varieties of cut flowers in the same vicinity of each other but unfortunately, sunflowers and zinnias should not be grown together,’ she explains.
‘Both require full day sun to bloom well and as sunflowers continue to grow, they will shade out any zinnias growing near them. The lack of sun can prevent zinnias from germinating and flowering.’
For a taller plant to compliment zinnias, cosmos are a great option. ‘They both prefer full sun and regular watering, and unlike the sunflowers, cosmos have a fine texture and airy growing habit that will not block out the sun,’ says Katie.
These colorful plants are also hugely popular with pollinators and flower at the same time, creating a dreamy display.
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6. Morning Glory
Fast growing with vigorous roots and sprawling stems morning glory - Ipomoea tricolor – is definitely one plant not to grow next to zinnias. Sun loving and happiest in moist, free draining soil it will quickly outgrow its stately neighbours, swamping these bright breezy annuals, entwining their upright stems with their far reaching and surprisingly strong tendrils.
Reaching up to 4’9’’ – 6’5’’ (1.5-2m) these summer flowering vines are best left to scramble over fences, up trellis and over obelisks so you can admire their array of trumpet blooms, in shades of blue, violet and pink.
Looking for a better-behaved flower lookalike, why not go for petunias? Their large, saucer like blooms come in every color, and many boldly colored varieties are splashed or delicately veined with white.
Long flowering and low growing, these tender annuals will allow zinnias to thrive happily alongside them without competing for nutrients or sun light.
Operations Manager at Holland Group, managing the customer service department and purchasing. Katie has been in the green industry since 2005 in the Greater Milwaukee area, earning her degree in Horticulture in 2008. She has been able to share her love for plants working in multiple garden centers, in sales positions and most recently in an online retail platform at Holland Group.
7. Tomato
Companion planting Companion planting can bring huge benefits to a vegetable garden, helping to attract pollinators, confuse pests, and create healthier, more resilient crops. But tomatoes and zinnias are one pairing that can become surprisingly problematic.
Both plants are hungry feeders with a strong appetite for nutrients, particularly phosphorus and potassium. Tomatoes need these nutrients to produce healthy fruits, while zinnias rely on them for vigorous growth and prolific flowering. In smaller beds or containers especially, this competition can quickly leave zinnias struggling to perform at their best.
Growth habit is another issue. Tomato plants are fast-growing and sprawling by nature, often expanding rapidly through summer and overshadowing neighboring flowers. Zinnias, with their upright stems and sun-loving blooms, can easily become crowded out.
Once airflow and sunlight are reduced, zinnias become far more vulnerable to common fungal problems such as powdery mildew, particularly during warm or humid weather. Dense tomato foliage can also trap moisture around the plants, creating conditions where disease spreads more easily.
For a similarly colorful and productive pairing, try planting zinnias near sweet peppers instead. Their shared love of sunshine makes them compatible companions, while the more compact habit of peppers allows zinnias to keep flowering freely without becoming crowded or shaded. You can find organic pepper seeds at Amazon.
If you are intrigued to find out more about plant pairings to go for and avoid, take a look at these companion planting mistakes and the best flowers to plant in a vegetable garden to deter pests.
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