The simple deadheading trick that keeps zinnias blooming all summer long

Garden experts explain how to deadhead, when to pinch back, and where to make the cut.

Key Takeaways

• The trick to deadheading zinnias is to cut at the little “V” where the stem branches, which encourages stronger stems and more blooms.
• Deadheading faded flowers keeps most zinnias blooming longer by directing the plant’s energy toward new flowers instead of seed production, though many newer bedding varieties will rebloom with little effort.
• Use clean, sharp pruners to remove spent blooms regularly to keep plants healthy, tidy, and flowering throughout the season.

We recently polled several gardeners, and zinnias were their top low-maintenance annual. It’s easy to see why. You could leave them pretty much alone in the summer heat, and they will not only continue to attract pollinators but will keep putting out a fair amount of colorful blooms. However, there’s a difference between your typical zinnias and those that look straight out of a garden tour. 

If you want yours to look their prime all season, you may need one simple form of upkeep: deadheading. We asked garden experts why deadheading zinnias makes such a difference and how to do it correctly. Here’s when to reach for the pruners—and when to leave this plant alone. 

Meet the Experts

• Jessica Cudnik, member of the National Garden Bureau and flower product manager at American Takii
• Lauren Kilpatrick, member of the National Garden Bureau and technical trials manager at Syngenta Flowers 
• Jessica Mercer, PhD, plant collector and senior horticulturist at Plant Addicts

Related: 5 Flowers You Should Deadhead in July for More Blooms All Summer Long

Why You Need to Deadhead Zinnias

Some annuals like zinnias are what gardeners refer to as “cut-and-come-again” plants. Basically, the more spent flowers you remove, the more the plant focuses on growing new blooms. “Zinnias respond to deadheading more noticeably than many annual flowers because they will continue to produce flowers until seed forms,” says Jessica Mercer, PhD, plant collector and senior horticulturist at Plant Addicts. “Once an old bloom starts forming seed, the plant puts energy there instead of sending up more flowers.” 

Types That Don’t Necessarily Need Deadheading

Your reason for growing zinnias and the type you have can affect whether you need to deadhead all season. “For cut flower zinnias, it is especially crucial to deadhead or harvest stems to signal to the plant to continue to bloom,” says Jessica Cudnik, flower product manager at American Takii. However, some varieties will keep blooming regardless. 

“For bedding-type zinnias—the more compact, highly branching type—the flowers might not need to be deadheaded,” says Cudnik. “The breeding has advanced to make the plant branch and continue to flower over the spent blooms.” Look for zinnias described as “compact,” “bushy,” or “highly branching,” as these are more likely to be bedding varieties.

For gardeners who’d rather not, Lauren Kilpatrick, technical trials manager at Syngenta Flowers, has two go-to recommendations. “Profusion or Zydeco are bred to be low-maintenance and will rebloom reliably with little or no deadheading,” she says. 

Is Deadheading Actually Necessary?

A little garden upkeep is rarely a wasted effort, so keep deadheading all types of zinnias. “It does use up plant energy to try and maintain mature and dying blooms,” Cudnik says. “So it doesn’t hurt to remove these, even on bedding zinnias, to make a more attractive plant.” 

Of all the varieties, Kilpatrick thinks the cut-flower types, like Benary’s Giant or Oklahoma series, do the best with regular deadheading. “The more you cut, the more they branch,” she says. But in most cases, skipping this chore won’t have a dramatic effect on your zinnias, regardless of the variety. “I would like to add that deadheading is not required,” says Kilpatrick. “Zinnias are generally self-cleaning—they’ll keep producing new blooms without any intervention.” 

Although deadheading is optional, Kilpatrick admits it has benefits, such as prolonging bloom cycles, preventing the spread of powdery mildew, and delaying zinnias from going to seed. “If you’re growing zinnias in a cutting garden or want peak performance, deadhead regularly,” she says. “If you just want color in the landscape with minimal effort, let them go—they’ll still deliver all season.”

When to Pinch Back vs. Deadhead

There are two strategic steps to keep your zinnias looking their best: pinching back and deadheading. “Pinching back is removing the growing tip to encourage more side branches and occurs when the zinnia is young, usually before flower buds appear,” says Mercer. “Deadheading means removing faded blooms so the plant keeps producing; it happens later, after the plant is flowering.”

In general, deadheading should be done all season, not just later in the summer. Mercer recommends checking zinnias every few days during peak growing season, or at least once a week if the plant is small. “A flower is ready to deadhead when the petals fade, dry, curl, or turn brown around the edges. The center may also start looking dry and seed-like,” she says. 

Also, if you’re going to commit to deadheading, try not to let faded flowers pile up. “Don’t wait to deadhead until the plant is covered in spent blooms,” says Mercer. “The plant will look tidier with regular deadheading and will continue putting energy into new blooms.”

To make it feel less taxing, weave deadheading into the time you’re already spending in your garden. “It doesn’t have to be an arduously dedicated event,” says Cudnik. “Simply remove spent blooms as you wander through your garden admiring all the beauty you grew this season!”

How to Correctly Deadhead Zinnias for More Blooms

Don’t overthink the process. While you can simply pinch off spent blooms with your fingers, the experts we spoke to prefer to use clean pruners to cut just above the next pair of healthy leaves or side shoots. But before you get to work, Kilpatrick recommends waiting until the plants are completely dry to help avoid spreading disease. 

Use Sharp, Clean Pruners

As for why you should deadhead with pruners, they’re less likely to damage the rest of the plant. “You can simply snap off old blooms with your hand by completely inverting the bloom, but this sometimes leads to extra damage if you accidentally take off more than you intended or pull the bloom off with a little too much energy,” says Cudnik. “You might even unintentionally pull the whole plant up!”

Mercer avoids removing blooms by hand because, as she puts it, “Zinnia stems can be tough, and tearing them by hand can damage the plant.” The other reason to reach for a pair of pruners is aesthetics. “It avoids the ‘stick in the air’ look,” says Cudnik. “When just the flower was removed, the left-behind stem can look a bit wonky.” Just make sure you clean your pruners before use!

Slow Down and Cut at the ‘V’

Regardless of your technique, aim for precision over speed. Think of it like a mindful ritual that helps you slow down and notice how your plants are changing. If you’re second-guessing where to cut, there’s an easy visual cue to remember: “Look for the little ‘V’ in the stem,” says Mercer. “Cutting there encourages new branching and better stems.” 

Don’t Remove Too Much

Mercer avoids removing too much healthy foliage because the leaves feed the plant. Once late summer comes, she also likes letting a few flowers go to seed. You can either let a few blooms drop their seeds naturally or collect them to plant again next year.

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