Pinch Out Young Dahlias for More Flowers and Stronger Plants

Many dahlias shoot upwards yet produce only a handful of flowers – one small, bold cut can change that completely.

Anyone who loves dahlias will know the problem: long, slender stems, abundant foliage, but only the occasional bloom. Professional growers use a remarkably simple remedy. It can seem almost ruthless, yet it produces many more flowers and sturdier plants. Getting the timing right is crucial – as is having the confidence to take the secateurs to what appears to be a perfectly healthy young plant.

What pinching out young dahlias involves

Every dahlia follows the same basic pattern: one main stem takes control, growing upwards, gathering strength and suppressing side shoots. The plant directs much of its energy into height and leaves rather than producing an abundance of flowers. Removing the tip of this stem early disrupts that internal order.

This is precisely the technique used by experienced gardeners: they cut away the growing tip of the main stem on a young dahlia. This encourages the plant to form several side shoots. Studies by, among others, the Royal Horticultural Society and the French research institute INRAE show that this can produce significantly more flowering shoots – often four to six rather than just one.

Pinching out the main tip early turns a tall, unsteady dahlia into a compact bush covered in flowers.

The visible result is that the plant stays shorter, branches more freely and has a generally more compact, robust appearance. Rather than toppling over in the first strong gust, it stands up far better to wind.

More flowers rather than a single show: the benefits of cutting back

Many home gardeners are surprised when their dahlias grow vigorously but produce very few blooms. Cutting them back early makes the plant spread its energy more widely:

• More side shoots instead of a single dominant main stem
• Four to six flowering shoots are possible instead of only one
• A substantially higher number of flowers throughout the season
• A sturdier plant with less risk of wind damage
• Better suited to cut flowers and colourful borders

One aspect puts many people off at first: the main flowering period starts a little later. Following a pinching-out cut, the onset of flowering is usually delayed by around ten to fifteen days. In return, the dahlia then flowers much more freely – the total number of blooms can rise three- to fourfold over the course of the season.

Professionals use this response deliberately, depending on their aim. Those seeking exceptionally large flowers, such as on so-called Dinner-Plate varieties, often leave the main stem intact and remove side shoots. For a home garden, however, the opposite is generally more appealing: plenty of medium-sized flowers to fill borders and vases. This is where an early cut shows its real value.

How to identify the ideal time to pinch out dahlias

The right moment determines whether the result is success or damage. As a rule of thumb, the dahlia should still be young while already looking sturdy.

Criterion	Ideal condition
Plant height	Around 20 to 30 centimetres
Number of true leaf pairs	Four to five clearly formed pairs
Stem thickness	Still relatively thin, solid and not hollow
Time since planting	Usually three to four weeks, depending on the weather

Ideally, choose a dry day. The cut surface will dry more quickly, reducing the risk of rot.

Step by step: how to pinch out young dahlias correctly

The procedure itself is straightforward provided that you follow a few basic rules:

• Check the plant: It should be around 25 centimetres high, have four to five pairs of leaves, and still have a stem that is neither thick nor hollow.
• Prepare your tool: Use a fingernail or small, sharp hand secateurs. Clean the tool with alcohol of around 70 per cent.
• Locate the main shoot: Choose the central, strongest stem; do not cut the weaker side shoots.
• Select the cutting point: Make the cut just above the second or third axis of a well-developed pair of leaves.
• Make a clean cut: Remove the tip with one decisive cut; do not crush or tear it away.

The height is important: remove only the shoot tip above the second or third leaf-pair axis, and do not cut any lower.

This cut removes the terminal bud area, which produces a plant hormone called auxin. Normally, this hormone keeps the side buds “held back” – a process specialists call apical dominance, meaning dominance of the tip. Once this influence has gone, the side buds awaken and begin to grow.

Common mistakes – and how to avoid them

The method itself is not difficult; it becomes risky mainly when it is used too late. As the dahlia stem thickens, it develops a hollow centre. Cutting it at that stage creates a small hollow where rainwater or watering water can collect.

From there, moisture can travel straight down towards the tubers. This may cause rot within just a few days, resulting in the plant collapsing or dying altogether.

Mistakes you should definitely avoid with dahlias

• Cutting too late: Do not pinch out stems that are more than about one centimetre in diameter.
• Cutting too low: Do not cut below the second leaf-pair axis, as this weakens the entire new growth.
• Wet weather: Do not cut during prolonged rain or immediately before heavy watering.
• Blunt tools: Bruising at the cut surface creates ideal entry points for fungi.
• Already weakened plants: Allow unhealthy dahlias to recover first rather than placing them under additional stress.

If your dahlias have already produced very sturdy, slightly hollow stems, it is better not to cut them. At this stage, a strong plant support is much more helpful than a late cut. Tie the plants in loosely and remove only faded flowers and damaged shoots.

Why pinching out dahlias is worthwhile despite the risk

The idea of deliberately cutting back a healthy young plant can feel wrong at first. Many home gardeners need one or two seasons to become comfortable with it. Those who take the step are usually rewarded with more flowers, stronger plants and, above all, an evenly filled border rather than isolated “sticks with a flower”.

The technique is particularly interesting for anyone who enjoys cutting bouquets. More shoots naturally mean more cut flowers without leaving the plant looking bare. Allowing flowers to bloom while harvesting them regularly also encourages the dahlia to form fresh buds.

A few extra professional tips for even better flowers

To ensure the cut delivers its full potential, it is worth considering care and position as well:

• Position: Choose a sunny, sheltered spot with loose soil. Heavy, wet soils increase the risk of tuber rot.
• Feeding: Feed moderately but regularly. Fertilisers slightly higher in phosphorus and potassium promote flowers and sturdiness, while too much nitrogen encourages leaves alone.
• Watering: Aim for moist soil rather than constantly wet conditions. It is better to water less often but thoroughly.
• Flower care: Remove spent blooms regularly so that the plant puts less energy into producing seed.

If you grow different varieties, you can also treat them differently: leave some plants uncut for very large individual blooms, while pinching others out early for many medium-sized flowers. This creates an interesting mix in the border that is visually effective too.

One further point is often underestimated: pinching out is not suitable only for large decorative varieties. Shorter bedding and pot dahlias benefit as well. Specimens grown in containers become noticeably more compact after cutting and are less likely to topple over, which is a real advantage on balconies or terraces.

Anyone wishing to try this approach gradually can start with just a few plants. A direct comparison between cut and uncut dahlias in the same border will show very clearly after only a few weeks how strongly this single early cut affects growth habit and flower production.