Want nice full zinnia plants with lots of flowers? The secret is pinching. By “pinching” or cutting back some stems while the plant is young, zinnias respond by creating more stems and that means more buds and blooms. Once you see how it works, you’ll want to make pinching part of your summer plant care.
For more, also see 7 Best Tips For Growing Zinnias to ensure a successful growing season.
Before we jump into the practical tips for pinching zinnias and why we do it, it’s helpful to understand more about these plants.
Zinnias are one of the most beloved annual flowers you can grow in your summer garden. With all sorts of eye-catching colors, shapes, sizes, and textures, it’s hard not to fall in love with all of them.
Zinnias are often confused with dahlias, and the two flowers have many visual similarities, especially with so many double-flowered varieties available these days.
Both are in the daisy family (Asteraceae) and have common native regions including Mexico. But below the soil surface you’ll find the key difference. Dahlias have tubers (tuberous roots) and zinnias do not. We grow zinnias from seed or cuttings.
There are a few dozen zinnia species in the wild, but the species sold through seed catalogues tend to be hybrids of Zinnia elegans, Z. augustifolia, and less commonly, Z. haageana and Z. Marylandica.
Some zinnias are short, growing just 6 to 8 inches tall like Thumbelinas, while others can reach upwards of 40-inches, or just over 3-feet tall including California Giants Mix.
The flowers can be fairly small—just two-inches in diameter—with others spanning 6-inches across.
But no matter the variety, any zinnia can be pinched.
- What is Pinching?
- Which Zinnias Should I Pinch Back?
- Pinch Again?
- Can I Pinch Back Repeatedly During the Growing Season?
- How to Pinch Zinnias
- Can I Propagate the Pinched Cutting?
- When Is It Too Late To Pinch?
What is Pinching?
Think of pinching as a form of pruning. And like all plant pruning, it is done in a specific way to serve a specific purpose.
For zinnias, pinching encourages the plant to branch out and produce more stems for a fuller appearance and more blooms.
Zinnias are so responsive to pinching, almost always sending out new stems, that it’s a routine task for many gardeners.
Is Pinching Necessary?
No, it’s completely optional. I really enjoy ongoing pinching to see what new growth appears and how many flowers I can get.
But, if you’re growing for traditional cut flowers, you may not want to. Instead, you may prefer a thick, single main stem and one gorgeous flower up top so the whole thing will stand nicely in a vase. That main stem is usually going to produce the biggest blooms while the flowers on branches tend to be a bit smaller. Still gorgeous, but smaller.
Which Zinnias Should I Pinch Back?
I pinch any zinnias that are expected to grow around 18-inches or taller and tend to be tall and leggy.
The zinnia in the photo (above) is a prime candidate for pinching. I’ll show you (below) how it changed after it was pinched back.
No matter what, I’d encourage you to try it and see what happens. Mark a stem with a piece of ribbon, pinch as shown (below) and monitor that plant as it forms new stems at the pinching site. It’s very interesting to see how they grow. And you get more flowers.
When to Pinch
Initially you can pinch back the stem when the established plant is perhaps 9 to12-inches tall (22 to 30 cm) and has several sets of leaves along the main stem. Do not pinch before you have several (at least three) leaf sets.
Can I continue pinching back zinnias during the growing season?
During the growing season, the plant will keep branching each time it is pinched until the growing season winds down. Zinnias are frost-sensitive, so when the colder temperatures set in, the party is over.
While researching this I noticed that professional growers are more likely to pinch early and then be done with it. This way, they get the plants producing the way they want and have them ready for market at a certain date.
Without any time pressures, home growers can keep pinching through the season, although the young plants (before budding and blooming) are most responsive.
How to Pinch Zinnias
Pinching removes the tip of a stem. It’s one simple cut. But the “tip” may be several inches or more of stem.
If the stems are still fairly slender and tender, you may be able to remove the desired section of stem with your fingernail. Hence, the term “pinching”.
I find it easier to get a nice, clean cut by using micro plant snippers.
To pinch or cut, follow a stem tip down to the first or second leaf nodes (where leaves join the stem) and snip or pinch it off just above that node. Cut on a diagonal if you can. The important part is to be sure not to cut into the leaf nodes—it’s from there that new branches form.
After cutting, you can leave those leaves as they are.
This next photo shows the zinnia a few weeks after pinching. You can see how the cut stem healed over and new stems grew just below the cut. You get two stems for the price of one.
And here’s the same plant with its new branches. You can really see what a difference it makes.
Can I Propagate the Pinched Cutting?
Yes, you sure can. Zinnias are one of the easiest cuttings to propagate.
For best results, use tender stems from early in the growing season, before the plant is flowering.
When we pinch, we make sure to cut above a leaf node.
For a cutting, we need to have a leaf node at the base of the cutting.
If you’re pinching and propagating, take a good cutting first, making sure you have nodes just above the cut.
Then, to finish the pinch, cut the stem again just above the next set of leaves.
Use these instructions to grow more zinnias from cuttings.
When Is It Too Late To Pinch?
You can continue pinching back throughout the growing season. While it does no harm, as summer ends and the days shorten you’ll eventually run out of time for new flowers to form.
The end of the season is the time to harvest zinnia seeds for next year.
~Melissa the Empress of Dirt ♛
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