If you grow zinnias for cut flowers, chances are you’ve heard about pinching back the plants in the spring to promote bushy growth. Well, what do you do with the healthy plant tops that you just cut off? Surely you don’t have to just toss them, right?
Nope! Use those cuttings to grow more zinnias and get even more blooms this season.
You can easily grow zinnias from cuttings as an easy way to propagate new flowers when pinching back young plants. You can also use cut flower stems, though the younger trimmings will root more easily and produce more vigorous growth. Zinnias grown from cuttings should bloom within eight weeks from transplanting.
Learning how to root and plant cuttings isn’t difficult, but a clear procedure can’t hurt, so keep reading to get all the steps involved in the process.
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Should You Grow Zinnias From Cuttings?
Growing zinnias from cuttings is a great way to use the cut stems after you pinch back young plants in the spring. Rooting and planting them is a much better way to use the trimmings than tossing them in the compost bin.
Rooting and planting zinnia cuttings is also a convenient way to use fewer seeds. Instead of sowing seeds for all the plants you want to have, sow half. Once the plants get to be 8-10 inches tall, cut them back by a third and root those cuttings (you’ll learn how in just a moment).
Voila, twice the plants from half the seeds.
Timing is essential to ensure successful blooms from new plants before they inevitably die back in the fall. Zinnia cuttings need at least eight weeks before they can produce healthy buds and blooms, so you need to ensure that you use the cuttings for propagation by mid-July.
If you need tips on how late you can plant (or sow) flowers for your season, head over to this article next: Plant Another Round Of Zinnias (It’s Not Too Late).
How To Grow Zinnias From Cuttings
Avoid throwing away healthy plant trimmings and use the following steps to propagate them instead.
1. Select fresh and healthy stems
If you like to pinch your zinnia plants in the spring to promote bushy growth, these cuttings are ideal for rooting and replanting. However, growing a new plant from cut flowers is also possible if that’s what you have to work with.
Zinnias can produce abundant flowers during the blooming season, which can last from late spring to early fall as long as soil temperatures remain warm enough at 60 – 80 °F. Regular pruning of spent flowers will encourage new and healthier blooms to develop.
While deadheading spent flowers is essential to encourage new blooms on the plant, these cuttings are not ideal for propagation. Old flowers and leaves have limited energy left in them, limiting the cutting’s ability to grow new roots from the leaf nodes. Mature and healthy flowers are a better option for propagation.
In addition, cuttings from younger plants tend to grow better than older plants. Cutting them early in the growing season when you’re pinching back anyway will provide you with enough cuttings that can yield continuous blooms the entire season.
2. Cut above a leaf node
When cutting flowers for propagation, you need to cut above a leaf node, which is where a set of leaves come out of the stem. Zinnia stems can be pretty long, with several leaf nodes. Ideally, cut a stem with several leaf nodes. Snip below a set of healthy leaves and immediately above the node of the next set of leaves.
Always use sterile gardening shears to protect your plant from the risk of microbial infection. To do so, just wipe down your clipper blades with rubbing alcohol, and you’re good to go. Using your freshly cleaned pruners, cut a flower stem with at least two leaf nodes with healthy leaves for water propagation.
Need some good clippers for the job? Check out my two 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.
Cut back the remaining stalk on the plant immediately above a leaf node and leave only ¼ – ½ inch (0.6 – 1.2 cm) of the stem to encourage regrowth. By limiting the amount of stem left behind, you’re helping the plant focus its energy on growing roots, not maintaining the foliage.
When cutting the stem, it also helps to cut at an angle of 45° to improve moisture absorption and reduce the risk of infection, just like if you were harvesting stems for a fresh bouquet
3. Remove the flower and bottom leaves if using a full stem
Cut zinnia flowers can last in a vase for 7 – 12 days, which is roughly about the same time before the cutting can grow roots. These cut flowers in a vase do not usually grow roots, making it challenging to propagate them, but you can take a few steps to help the cuttings along.
Removing the flowers can help the cutting focus on growing roots instead of maintaining the blooms. Cut the flower stalk back to an inch (2.5 cm) above a set of leaves.
Snip the bottom part of the stem to just an inch (2.5 cm) below the lowest leaf node. Also, carefully pluck out the bottom leaves to help prevent soaking them in water and causing moisture-related infections like powdery mildew, which many zinnia cultivars are susceptible to.
4. Soak the stem in clean water
Soak the stem in clean distilled water, submerging the part of the stem where you removed the bottom leaves. The water will encourage the plant’s nodes to grow roots instead of new leaves. Replace the water every two days so the stem gets fresh oxygen and reduces the risk of bacterial growth
5. Keep the setup away from direct sunlight
Zinnias grow best in hot summer conditions, but cuttings need protection from direct sunlight while they grow roots. The sunlight can stress the cuttings, causing them to lose moisture throughout the day and slow down their new root formation.
Any spot with indirect light will work, such as a low-light window sill or, in my case, the kitchen counter, which helps me remember to freshen the water every other day.
6. Pot the rooted cuttings and harden them off for planting
After the cutting has grown enough roots and new leaves to support itself, you can plant it in moist soil and begin to slowly acclimate the young plant to the outside sun and weather.
This process is called hardening off, and it’s the same process all seedlings started indoors need to go through to survive transplanting into the garden.
You will slowly expose the tender plant to more and stronger sunlight every day, and in roughly two weeks, it will be ready to plant out in your garden. Without this transition period, the cutting would likely die from the sudden change in the environment from indoors to out.
Here’s a quick summary of how to be successful with growing from cuttings:
- You can grow zinnias from cuttings, preferably young stems taken when pinching back healthy plants
- You will have better chances of success by using cuttings without blooms, but it’s also possible to use cut flowers.
- These cuttings can grow roots naturally with the proper cutting technique and growing environment.
Best of luck with your zinnias! If you follow the steps in this guide, you should have no problem growing a flourishing batch of colorful flowers.