Including a swath of zinnias in any garden is a must-do. Whether planted en masse in a flower bed or lined up along the edge of a veggie garden, zinnias add color, attract pollinators, and provide blooms for cutting all summer long.
Even though zinnias are prolific bloomers all on their own, there are a few key times to break out your garden clippers and make a cut to promote even more blooms.
There are three prime times to make cuts on your plants to promote more zinnia blooms. Pinch the young plants to encourage growth, harvest flowering stems regularly throughout the season, and deadhead old blooms to prevent the development of seeds.
Let’s get into the details of when and how to cut your zinnias for maximum flower production.
If you like to listen to your information, check out this podcast episode for tips on zinnias and other cut flowers:
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Three techniques to keep your zinnias in bloom
1. Start early with pinching to promote branching
This step takes a little planning to catch your plants earlier in the season. Don’t worry if you already missed the time; continue with the other two tips. If you’re getting a jump on your season by reading this in spring, then learn how to use pinching to get more blooms.
Pinching flowers means letting the plants grow to about 12 inches tall, then cutting off the top 3-4 inches, right above a set of leaves. Pinching flowers this way will encourage the plant to grow more lateral branches, resulting in more stems producing blooms.
It might feel awkward to cut off a third of your healthy plant. I’ve been there, filled with doubt that taking off growth will yield more growth. It seems counterintuitive, but it does work. Many cut flowers benefit from pinching, such as cosmos, salvia, and snapdragons.
Even if you’re growing zinnias to enjoy in the garden and you don’t want to cut any for bouquets, pinching can still be helpful. The pollinators that visit your zinnias, such as butterflies and bees, will be appreciative of any extra blooms they can find throughout the season, so go ahead and give your zinnias that trim early in the season.
2. Cut often during summer to promote new flower buds
If you missed the window to pinch your zinnias when they were young, you still have two reliable methods to keep them blooming when they’ve matured.
Cutting blooming stems throughout the week will encourage zinnias to produce flowers throughout the warm summer season. Fortunately, zinnias make an excellent, long-lasting cut flower, so harvesting regularly is a pleasure.
Use the wiggle test to decide which stems are ready to be cut. Grab the stem about eight inches below the flower and gently wiggle it back and forth.
If the flower head flops on top of the stem, the flower is too immature to pick. If the stem is sturdy and the flower head stays relatively still, then it’s a great time to cut it for a counter-top bouquet.
Put the cut stem in a jar or bucket of cold water right after you cut it to keep your zinnias fresh in the vase as long as possible. Once you get the stems in the house, strip the bottom two-thirds of the stem of any leaves. If left on the stem to sit in the water, the leaves will rot and promote bacterial growth.
Recut the stem at a 45-degree angle after you strip it. The angled cut will allow for the greatest surface area for the stem to draw up water. Keep the flowers out of direct sunlight and change the water every day or two to keep the flowers fresh and enjoy those blooms as long as possible.
Need some snips for the job? Here are my favorite pairs:
My favorite garden shears
I constantly misplace my garden shears and clippers, so I’ve tested a lot of pairs. Good thing these ones have red handles to help me keep track of them!
- Corona Leaf & Stem Micro Snips: Perfect for cutting small stems, deadheading spent blooms, or keeping the mint plant from taking over my garden.
- FELCO Classic Manual Hand Pruners: Better for heavier-duty pruning, such as dead sunflower stalks and tomato vines and cutting old zip-ties off the trellises.
Want to know more tips about zinnia blooms, like how long you can expect to harvest off your plants? Then jump over to this article, 7 Things You Should Know About Zinnia Blooms, when you’re done here.
3. Deadhead any flowers you don’t harvest
Finally, if you want to enjoy your zinnias right in the garden (along with all the butterflies), then deadheading is the trick for you to keep your flowers blooming.
Deadheading flowers means removing the old flower after it’s done blooming. Once the flower petals start to wilt and look ragged, cut the stem just above a set of leaves. Removing the spent bloom will prevent it from going to seed, gradually slowing down flower production by the plant.
Here are a couple of examples with some calendula flowers. One stem got away from me completely and went to seed. The other is a bloom just past its prime.
Since the plant’s goal is to produce seeds, if you never remove the spent blossoms, it will reach its goal much more quickly. If the plant has succeeded in making seeds, then there’s no reason for it to continue making flowers, and the plant will die back sooner than later.
By removing the old flowers, you’re delaying the seed-setting process and encouraging the plant to make another attempt by putting out fresh flowers. Keep the cycle going all season, and you’ll (almost) never run out of flowers.
If you’re not sure which of your flowers will need deadheading, check out this post, Should I Deadhead my Cut Flowers, Too? and learn which flowers you can help keep in bloom with a timely snip.
After a while, though, you’ll have a choice to make in the life of your zinnias. Either replace the plant or leave it to feed the birds.
Here’s a little more detail to help you decide which option to choose:
Even if you remove every old flower, eventually, the zinnias will get run out of energy and start to slow down. The plant will look a bit ragged, and a common disease for zinnias, powdery mildew, might even set in.
At that point, it’s best to cut down or pull the plant from the garden and replace it with a new one, whether that’s another zinnia or something different.
If you’re reaching the end of your season, consider leaving the old plants in place. Allow the flowers to go to seed after all, and you’ll be providing food and habitat for birds and bugs as the season transitions to fall and winter.
You can remove the old plant at the first sign of spring to make room for all the new plants you have for the garden.
For a handful of other ways to keep your flower garden blooming, jump over to this post, 6 Summer Chores To Keep Your Cut Flower Garden Performing.
How long will zinnias bloom?
Zinnias will reliably bloom all summer as long as the weather stays warm. If you live in an area with long summers, this usually means that zinnia plants will produce flowers until September or later. Once the first frost arrives and temperatures drop to the 30s, the zinnia plants are done for the season as they won’t survive a frost.
When do zinnias bloom?
Zinnias will typically start blooming 60-90 days after planting from seed. If you sow the seeds after the risk of frost has passed in April, that means you will get flowers sometime in July or August. A May sowing will likely yield blooms in August because they’ve been sown into warm soil.
How long do zinnia blooms last?
Zinnia blooms will last for up to two weeks after cutting for the vase. They’ll last equally long, if not longer, on the plant. Overall, a zinnia plant should produce flowers for at least a month, but with regular water and a midseason boost of fertilizer, your zinnia plants should last a couple of months.