ANNUALS > COSMOS > PINCHING-OUT
By ELIZABETH WADDINGTON Elizabeth Waddington, MA, Dip.Perm.Des. - Garden Designer Elizabeth is a Permaculture Garden Designer, Sustainability Consultant and Professional Writer, working as an advocate for positive change. She graduated from the University of St. Andrews with an MA in English and Philosophy and obtained a Diploma in Applied Permaculture Design from the Permaculture Association. Roy Nicol, MHort (RHS), MCIHort - Horticulturist Roy is a Professional Gardener and Horticultural Consultant, specialising in large garden year-round maintenance and garden development. He is an RHS Master of Horticulture and uses his research in the application of no-dig methods in ornamental garden settings. Roy has been a Professional Gardener for more than six years and is a member of the Chartered Institute of Horticulture, Professional Gardener's Guild and Association of Professional Landscapers (Professional Gardener).
Reviewed By ROY NICOL 
IN THIS GUIDE
- What Does ‘Pinching Out’ Mean?
- When To Pinch Out Cosmos
- How To Pinch Out Cosmos
Cosmos plants are easy and straightforward flowering annuals to grow in a garden.
As long as you can provide a sunny location with moist yet free-draining conditions, they could be a great addition to your space.
However, to make sure that your cosmos thrive in your garden, it is important to care for them correctly.
Of course, you need to think about things like watering and fertility, but there are also a few other things that you can do to get the best possible results.
One of these is pinching out.
| Difficulty | Easy |
| When To Pinch Out | March to May |
What Does ‘Pinching Out’ Mean?
When we talk about ‘pinching out’, we are referring to the process of nipping off the main growing tip of a plant when it reaches a certain size, in order to encourage the plant to bush out and become lusher, fuller and less spindly.
This is something that is often recommended for certain plants – cosmos included.
This process is not absolutely essential, but it can help you to grow cosmos that look good and perform at their best.
Pinching out cosmos can be a good idea because it will improve the appearance of the plants and help ensure that they have a full and bushy appearance.
What’s more, while pinching out won’t have this effect on all plants, pinching back the top growth on cosmos can also encourage the plant to produce more blooms.
“As cosmos flowers best when the day lengths become shorter in the late summer and autumn, the process of pinching-out helps to maximise the flowering potential of the plant at this time,” shares Horticultural Consultant Roy Nicol.
When To Pinch Out Cosmos
You should pinch out the growing tip of a cosmos seedling when the plant has developed its first 2-3 sets of true leaves.
This is a job that you will do in the spring, after sowing the seeds sometime between March and May (depending on where you live and whether you are sowing indoors or outdoors).
Precisely how long plants will take to reach this stage will depend on the specific variety and the growing conditions.
How To Pinch Out Cosmos
This process could not be simpler.
Pinching out simply involves taking a finger and thumb and nipping off the top of each growing stem down to just above the next set of leaves.
“Alternatively a pair of sharp, clean secateurs can be used to cut off the stem neatly at the correct point,” says Roy.
This video from Van Meuwen shows this simple process in more detail:
By pinching away the top of these stems, your cosmos will focus more of its energy on developing side shoots on existing stems – thereby helping the plant to ‘fill out’ and become bushier.
It might seem counterintuitive to curtail the growth of the plants in this way, but this process can avoid issues caused by legginess – and help to ensure that you get healthier, more attractive, bushier and more abundantly flowering plants later in the growing season.
After you have pinched back your cosmos, you should begin to see new side shoots forming within a matter of days.
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