Zinnias are some of the easiest flowers for beginners to grow in a cut-flower garden. They come in an array of colors, shapes, and sizes and are just so fun to grow.
Birds, bees, and butterflies adore zinnia flowers, and I find that the zinnia patch in my cut-flower garden is the perfect setting to sit and watch these busy, beautiful creatures.
Additionally, zinnias have a long vase life. I have had some zinnias last two weeks in the vase before fading.
If you’re growing zinnias in your cut-flower garden this year, there are some tips you should know to get the best blooms for the vase.
I’m sharing my best tips for growing better zinnias so you can make the most of your zinnias this season!
8 Tips for Growing Better Zinnias
Here are my 8 tips to help you get the best blooms from your garden to the vase.
Tip #1: Wait to Plant Zinnias
Zinnias love the heat and sun, so if you live in a cold climate, like I do in the Midwest, wait until the soil is truly warm before planting zinnias.
It can be tempting to plant out zinnias on the first warm day of spring, but often the weather changes back to cool or the soil is actually still too cold for heat-loving plants like zinnias.
Zinnias are fast growers when they are planted in the right conditions (full sun and warm air temps). Do your best to wait until soil temperatures are at least 70°F or 21°C before planting zinnia seeds or young transplants.
If you’ve never grown zinnias in your garden before, check out my guide to growing zinnias from seed!
Tip #2: Pinch Zinnias
When zinnia plants are about a foot tall (30 cm) and have at least 2 sets of true leaves, you should cut off the growing tips just above a set of true leaves.
This is known as “pinching.” Pinching cut-and-come-again flowers like zinnias will cause the plants to produce multiple stems from the cut and longer stem length.
Although it can be hard to bring yourself to cut the plants when they are young, the reward of more long-stemmed flowers is worth it!
One thing to keep in mind is that pinched zinnias will take a bit longer to produce blooms. If you’re impatient and want flowers right away, try pinching half of your plants and leaving the other half to bloom. Then when you harvest the first wave of flowers, cut deeply into the plant, leaving it about a foot (30 cm) tall.
Tip #3: Wait to Harvest
Before cutting zinnia blooms, wait until the flowers have completely opened. Some zinnias like those in the Queeny Lime series and Lilliput series continue producing more and more petals.
For the fluffiest flowers, give freshly bloomed zinnias time to produce more petals, especially if you’re after that “beehive” or “ball” look.
Tip #4: Do the Wiggle Test
Once your zinnia flowers have opened up, do the wiggle test before cutting them. Grab the stem several inches below the flower head and shake the stem. If the stem is wiggly or droopy, it is not ready to cut. If the stem remains firm and erect, then the zinnia is ready to harvest.
Don’t forget to follow the best practices for making zinnias last post-harvest. I go through each tip in this post on making flowers last in the vase.
Tip #5: Succession Plant Zinnias
Plant a second wave of zinnias halfway through the summer even if your original zinnias are still doing fine. Although zinnias produce well in my garden all season long, I do find that they begin to get tired and more prone to disease by the end of summer.
In my own cutting garden, I usually have an empty spot open up around mid-summer when the spring flowers like bachelor’s buttons or larkspur have faded and gone to seed. This is the perfect spot and time to plant another wave of heat-loving flowers like zinnias.
Tip #6: Don’t Over-Fertilize
Heavy-feeding annuals like crops in the vegetable garden often require supplemental feeding to keep them productive and strong. Zinnias are different.
They don’t need supplemental fertilizer and feeding them too much will cause abundant leaves and fewer blooms.
Instead, supply zinnias with good soil at the time of planting by adding a top dressing of well-rotted compost, or a slow-release, balanced organic fertilizer (the NPK numbers are all the same, such as 2-2-2).
If you want to boost your zinnia flowers, use a high-phosphorus (the middle number in NPK) fertilizer once the plants are actively blooming.
Tip #7: Provide Plant Supports for Zinnias
My zinnias generally have pretty strong stems, but even the strongest zinnias get blown over in a heavy rainstorm. To prevent stems from breaking or plants from being uprooted from the weight of the blooms, use plant supports when you sow seeds or transplant flowers into your garden.
Many professional flower growers use Hortonova netting attached to hoops or stakes. I do something similar using string.
My favorite way to support flowering plants is to stake each corner of my zinnia bed with sturdy T-posts. Then I tie heavy-duty string around the corners and make an X in the center starting at a 18″ (45 cm) above ground and then another foot (30 cm) above that. I end up with two tiers of string support for the plants to grow through.
Tip #8: Deadhead Regularly
I don’t often pick every single bloom out in my cut-flower garden, but I do make sure to deadhead spent blooms.
Deadheading is a common flower gardening practice of removing flowers before they set seed. Deadheading tells flowering plants to make more flowers!
Gardeners typically remove only the spent blooms, but if you are growing the flowers for cutting, snip spent blooms on long stems as if you were harvesting for the vase.
This not only keeps the plant blooming, but also causes zinnia plants to continue blooming on long stems.
Favorite Zinnias to Grow
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Here are a few of my favorite zinnias to grow for cut flowers in case you’re looking for recommendations.
- Queeny Red Lime – fully double flowers with lime green petals change to iridescent reddish pink
- Queeny Lime with Blotch – fully double flowers with lime green petals mixed with pink
- Benary’s Giant Pink – huge pink zinnias
- Lilliput Mix – little beehive-shaped zinnias
- Señora Zinnia – ruffly, cactus petals in peach pink shades
Following these 8 tips on caring for and harvesting zinnias will help you grow the best zinnias from your garden to your vase. Once you get the hang of growing zinnias, these tips will be second nature to you.
If you have any other tips or questions, please leave them in the comments below!