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When and How to Cut Back Zinnias in Your Garden

Zinnias are incredibly productive annuals that create a wonderful bounty of colorful flowers. Although zinnias are low-maintenance, a little bit of effort can increase the number of flowers that you get. To encourage your zinnia to produce more flowers, it’s a good idea to prune and deadhead the plant. In this article, we’ll show you when and how to cut back and deadhead zinnia flowers in your garden.


Cutting Back and Deadheading Zinnia Flowers – The Essentials

Once your zinnia is about 8 to 12 inches tall, cut off the top 4 inches of the stem. This encourages the zinnia to produce more stems and more blooms. Deadhead wilting zinnia blooms during the season to make way for new flowers. As annuals, zinnias die back in the winter and won’t need cutting back.


Botanical Overview

Name:Zinnia
Scientific Name:Zinnia spp.
Native Range:Mexico, Southwestern United States, parts of Central and South America
Growing Zones:USDA Zones 2 to 11
Botanical Characteristics:Composite flowers that can be single, double, or semi-double growing on stems ranging from 1 to 4 feet tall
Flowering Season:Early summer until first fall frosts
Colors:Pink, purple, orange, red, yellow, green, white
Toxicity: Non-toxic to humans, pets, and other animals.

Is Cutting Back and Deadheading Zinnia Flowers Necessary?

Is Cutting Back and Deadheading Zinnia Flowers Necessary?

Zinnias are some of the easiest flowers to grow and come in a wide range of colorful cultivars. As long as they get plenty of sunlight, regular watering in well-draining soil, and fertilizing, zinnias are extremely prolific flowering annuals. As such, cutting back and deadheading zinnia flowers isn’t strictly necessary.

However, if you do decide to cut zinnias back, you’ll get a bigger bounty of blooms. Zinnias are popular and symbolic cut flowers, so adopting a cut-and-come-again approach means you can harvest them for long periods (and dry and preserve them for even longer). Once you take a zinnia cutting, the plant will redirect its energy to produce new flowers.

If you want the best possible zinnia crop, you can cut back the tops of young plants. This encourages the plant to produce several new stems that will each develop into fabulous flowers. It’s best to do this before the plant begins to flower to maximize the dazzling display.

Zinnias produce large, beautiful flowers in a range of colors, from pink, purple, orange, red, green, and white. However, old flowers will start to wilt or turn brown. So if you want your zinnias to look their best, deadheading them is necessary. Deadheading these spent blooms make the other healthy flowers look even better.

At the end of the flowering season, zinnias will start to die off once exposed to frost. Zinnias are annuals, meaning each plant only lasts one year. Unlike perennials, you won’t have to cut back zinnias after the season ends to prepare them for next year.

Key Considerations When Cutting Back & Deadheading Zinnias

Key Considerations When Cutting Back & Deadheading Zinnias

Before you start pruning or deadheading your zinnias, it’s important to sterilize your gardening tools. Whenever you cut a plant, the fresh cut is vulnerable to diseases and pests that can be transferred from other plants. Sterilize your pruning shears and other tools with a 5% bleach solution to avoid this problem.

It’s also crucial to ensure that your shears or scissors are sharp. This ensures the cut will be clean, reducing the risk of diseases or pests attacking your zinnia. Use a sharpening stone to keep your pruning shears or secateurs in good condition.

Although pruning and deadheading are beneficial for zinnias, it’s essential not to remove too much of the plant at once. Cutting back too much of the zinnia weakens the plant, impairing its ability to produce flowers. Never remove more than a third or a quarter of the total number of stems at once.

When to Cut Back Zinnias

When to Cut Back Zinnias

For the best results, prune zinnias when they’re relatively young and before they start flowering. The plant should have reached 8 to 12 inches in height before considering pruning it. Each plant should also have at least two sets of leaves, and the stem should feel firm. If the stem still feels soft, wait for a few more days before trying again.

Removing the tops of the plants at this stage is called “pinching”. This stimulates bushier growth as the plant produces multiple stems from the cut. Each of these stems will go on to produce a beautiful flower.

When to Deadhead Zinnia Flowers

Zinnias usually bloom from early summer until the first frost of fall. Deadheading throughout the season helps your zinnia produce as many flowers as possible before fall arrives. Once a flower has started to wilt or turn brown, snip it off to help the plant concentrate on young buds.

How to Prune Zinnias

How to Prune Zinnias

Pinching, pruning, and deadheading are the three main ways of cutting back zinnias. Each method serves a particular purpose and needs to be done at certain times during the season. When harvesting your zinnias, cutting them in the right way also helps promote more blooms. 

Pinching

Pinching is a way of stimulating a zinnia plant to produce more stems and should be done when the plant is young. Once your zinnia has reached a height between 8 and 12 inches, it can be pinched. Make sure that the stem feels firm and has at least two sets of leaves. If the stem isn’t firm, hold off on pinching for a few days until the stem feels stronger.

Using clean, sharp shears or scissors, cut the top 4 inches off the young plant. Although this may seem counter-intuitive, the plant will respond by producing multiple new stems from the cut. This creates a bushier zinnia plant that will yield lots of gorgeous flowers throughout the season.

Pruning

You may need to prune your zinnias throughout various stages of the season. Pruning is usually only necessary if your zinnias have become infected with diseases or pests. Using sharp, clean tools, cut off any infected stems, leaves, or flowers to stop the problem from spreading.

Deadheading

Although zinnias produce beautiful showy flowers, these blooms will deteriorate over time. Once they start wilting or turning brown, you can deadhead them. This helps your zinnia produce fresh flowers from younger buds while maintaining the beauty of the plant.

Interestingly, you can use deadheading as a way to control the size of your zinnias. If you want a more compact zinnia, snip off more of the stem when you deadhead a spent flower. The stem will then grow closer to the ground.

If you want to keep the height of your zinnia, remove less of the stem whenever you deadhead wilted blooms. As the plant recovers, new flowers will appear higher on the stem.

Harvesting

When it’s time to harvest cut flowers from your zinnia, cutting in the right place encourages more flowers to develop. Choose a firm flower stem that’s branched off from the main plant. Cut the stem as close as possible to the joint with the main plant, just above a set of leaves.

Using this method allows your zinnia to produce another flower in place of the stem you harvested. This cut-and-come-again ability is a big reason why zinnias make excellent cut flowers.

Cutting Back

Unlike perennials, annuals like zinnias don’t need cutting back at the end of the season. Instead, annuals die back naturally once the season is over because they only last a single year. Once your zinnias have finished flowering, leave the last flower heads on the plant and collect the seeds. You can then use the seeds to grow next year’s zinnia crop.


Wrapping Up

With the proper care and attention, zinnias can provide a huge crop of fabulous cut flowers. To get as many flower stems as possible, pinch your zinnias once they reach 8 to 12 inches tall. Deadhead any spent flowers throughout the zinnia flowering season to encourage new blooms. Always use clean, sharp tools and only cut stems that feel nice and firm.


Edward Hodsdon
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Edd is a budding content writer and gardener living in the United Kingdom. He has a bachelor's degree in Creative and Professional Writing and has written for several gardening publications online. He is passionate about nature and sustainability with a focus on gardening and wildlife.

Author

Edd is a budding content writer and gardener living in the United Kingdom. He has a bachelor's degree in Creative and Professional Writing and has written for several gardening publications online. He is passionate about nature and sustainability with a focus on gardening and wildlife.

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