How and why you must pinch out your dahlias 🌱

If you’ve ever grown dahlias and ended up with one tall stem and only a few flowers, there’s a good chance you skipped one very important step: pinching out.

The good news? It’s incredibly easy, takes about ten seconds per plant and can completely change the shape, strength and flower production of your dahlias for the rest of the season.

Let’s break it all down properly.

What Does “Pinching Out” Actually Mean?

Pinching out simply means removing the growing tip from each of the stems - the most stems, the more tops you have to 'pinch' out.

You literally pinch or snip off the top off each shoot once the plant has three or four pairs of leaves. In the photo below, the plant has three pairs of leaves.

It feels brutal the first time you do it. Most people stare at their healthy new growth thinking: “You want me to cut THAT off?!” But what you’re actually doing is encouraging the plant to stop growing as one single stem and instead branch out sideways.

Think of it as redirecting the plant’s energy from “up” to “out”.

Why Pinching Out Is Important

1. You Get More Flowers

This is the big one. A dahlia left untouched will naturally produce one dominant main stem. That means fewer branches and ultimately fewer flowers.

When you pinch out the top, the plant responds by producing multiple side shoots:

🌱 More shoots = more stems

🌱 More stems = more flowers

Within a week you should start to see stems starting to sprout from where the leaves join the stem. I like to call this the 'arm pits'!

2. You Create Bushier, Stronger Plants

Unpinched dahlias can become tall and leggy, especially if they were started indoors on a windowsill with limited light. Pinching encourages a sturdier, fuller shape with stronger lower growth.

This matters later in the season when your plants are heavy with flowers and dealing with wind and rain. Bushier plants tend to hold themselves far better.

You can see below that some of the dahlias I had on the bottom row of staging in my greenhouse were getting leggy, so I have been pinching these this week to help them grow stronger.

3. Better Stem Length for Cutting

If you grow dahlias for cutting, pinching is especially important.

Those side shoots that develop after pinching often produce longer, more usable stems for bouquets and arrangements AND the fact that you will have more stems, naturally means more flowers.

4. Improved Airflow and Plant Health

A well-shaped plant with evenly spaced stems allows better airflow through the centre of the plant.

Good airflow helps reduce humidity build-up and can lower the risk of issues like powdery mildew later in the season.

When Should You Pinch Out Dahlias?

The ideal time is when your dahlia plant is around:

🌱 20–30cm tall

🌱 Has at least 3 to 5 sets of leaves

🌱 Looks healthy and actively growing

This dahlia below is Night Silence and is a good example of a plant with 4 sets of leaves and the top pinched out.

For most people in the UK, this usually happens in late spring to early summer depending on when the tubers were started. FYI I only have three of four plants that are ready to be pinched and I started them in my greenhouse over 4 weeks ago now. So if your plants are not at this stage yet, don't worry. They'll get there!

My dahlia tubers are outside in full sun all day now and covered at night if the temperatures drop below 5 degrees but you can see from this photo, none of these are ready for pinching.

Exactly Where Do You Pinch?

Look for the main central stem and count three or four pairs of leaves. You want to remove the growing tip just above where the leaves join the stem.

🌱 Leave the lower leaves intact

🍃 Remove the soft top growth

🪴 Keep 3–4 strong leaf sets below

🌸 New shoots will then emerge from the nodes beneath where you cut.

Within a week or two, you’ll usually see multiple new stems forming.

Can You Use Scissors?

Yes, absolutely. Young stems are soft, so this is usually very easy. You can:

👌 Use your fingers to pinch

✂️ Use clean scissors

✂️ Use snips or secateurs

What Happens If You Don’t Pinch Out?

Your dahlia will still grow. Many beginners panic that they’ve “ruined” things if they forgot. You haven’t - and unpinched dahlias still flower beautifully, but they often:

• Produce fewer stems

• Become taller with less flowers

• Need more staking

• Are not as attractive as they can look like a sunflower!

Will Pinching Delay Flowers?

Very slightly, yes. Usually by around a week or two.

But in exchange, you get:

🌸 More blooms

🌸 Better plant shape

🌸 Longer stems

🌸 More cutting stems

It’s very much a “short-term sacrifice, long-term gain” situation. A tiny pause now often creates a much better plant by midsummer.

Should You Pinch Dahlias Grown in Pots?

Definitely. In fact, container-grown dahlias often benefit enormously because pinching helps prevent them becoming top-heavy.

Bushier plants in pots tend to look fuller, balance better visually (and need less emergency staking later!)

What If Your Dahlia Already Looks Tall and Leggy?

Pinching can still help. Leggy growth often happens when tubers are started too warm or with insufficient light indoors - and removing the top encourages lower branching and can help rebalance the plant.

A Quick Note About “Stopping”

You may hear experienced growers use the word “stopping” - and this is essentially the same thing as pinching out.

Commercial growers and cut flower growers often say they are “stopping” dahlias to encourage branching. Different term. Same process.

Final Thoughts

Pinching out feels wrong the first time you do it. You spend weeks willing your dahlias into life and then someone tells you to cut the best bit off! Very rude behaviour from the gardening world.

But once you’ve seen the difference side by side, it becomes one of those jobs you never skip again.

A pinched dahlia is usually fuller, stronger and easier to manage.

And ultimately, that means more flowers for longer. Which is really the whole point of dahlias in the first place 🌸