One dahlia tuber can become several plants

If one dahlia plant is good, several identical plants are obviously better.

Taking cuttings is one of my favourite ways to multiply a special dahlia without waiting for the tuber clump to grow large enough to divide. It is especially useful when you have a variety you love, a new seedling you want to preserve or one precious tuber from which you would like to grow more plants.

A successful dahlia cutting becomes a genetic clone of its parent. Unlike a dahlia grown from seed, which will produce its own unique flower, a cutting should retain the colour, form and characteristics of the original plant.

At Femme Pétale, I take cuttings from selected tubers and plants to increase varieties I want to grow, preserve promising flowers and create more plants from limited stock.

It may feel slightly alarming the first time you remove a perfectly healthy shoot, but dahlias are often more generous than we give them credit for.

What is a dahlia cutting?

A dahlia cutting is a young shoot removed from a growing tuber or an actively growing plant and encouraged to produce its own roots.

The two types you are most likely to use are:

Basal cuttings

These are young shoots taken close to the crown of a sprouting tuber. This is the method I use when waking tubers specifically for propagation.

Softwood or tip cuttings

These are taken from fresh, non-flowering growth on an established plant. The growing tip removed while pinching a young dahlia can sometimes be prepared and rooted rather than discarded.

Why take cuttings instead of simply dividing the tuber?

Dividing tubers is a reliable way to multiply dahlias, but each viable division needs:

• A firm tuber body
• An intact neck
• A piece of crown
• At least one viable eye

A clump can only be divided into as many viable pieces as its structure allows.

Cuttings allow you to produce several new plants from one tuber without cutting that tuber into increasingly risky divisions.

Cuttings are useful when you want to:

• Multiply a rare or valuable variety
• Increase your stock more quickly
• Preserve a favourite seed-grown dahlia
• Replace a plant that has produced a poor tuber clump
• Grow several plants from one healthy mother tuber
• Create additional planting material for your cutting garden
• Practise propagation without sacrificing the original tuber

A rooted cutting can grow into a full dahlia plant and may produce its own tubers by the end of the growing season.

When should you take dahlia cuttings in South Africa?

The ideal time is when your tubers are waking and producing strong young shoots.

In Pretoria, I generally begin during late winter and spring as the weather warms and I prepare for the new growing season. The exact timing will depend on your climate, frost dates and growing setup.

If you have a protected greenhouse, propagation area or warm indoor space with good light, you may be able to start earlier. If you do not have protection, wait until temperatures are more stable.

What you will need

Prepare everything before removing the shoot:

• A healthy, correctly labelled dahlia tuber or mother plant
• Clean, sharp snips, scissors or a propagation knife
• Small pots, cells or propagation trays
• A clean, light and free-draining propagation medium
• A dibber, pencil or narrow stick
• Plant labels
• A spray bottle or fine watering rose
• A warm or even humid environment like a greenhouse or warm room with loads of light
• Rooting hormone, if you choose to use it

Rooting hormone can help, but it is not a substitute for healthy material, clean tools and the correct moisture level.

Step 01 / Preparation Wake the tuber

Place the tuber or clump into a shallow tray or pot of lightly moist growing medium.

Keep the crown and eyes visible rather than burying everything deeply. You need to see where each shoot emerges so that you can work carefully around the crown.

Place the tuber somewhere warm and bright, out of harsh midday sun.

Keep the medium lightly moist. A dormant tuber does not need to sit in saturated soil. Too much water at this stage can encourage rot before the shoots are established.

Depending on the tuber and growing conditions, new shoots may begin appearing within a few weeks.

Step 02 / Selection Choose the right shoot

Choose a healthy, compact shoot with:

• Strong green growth
• No visible pests or damage
• No signs of distortion or disease
• Approximately two or three sets of leaves
• A stem long enough to handle without crushing it

A shoot around 7 to 10 centimetres long is usually manageable.

Avoid very soft, stretched growth. Long, pale shoots are often a sign that the tuber has not received enough light.

Also avoid taking cuttings from plants showing suspicious mottling, severe distortion, unusual proliferation of shoots or abnormal growth around the crown. Propagation multiplies problems as efficiently as it multiplies good plants.

Step 03 / Cutting Remove the cutting

Use a clean, sharp blade to remove the shoot close to the tuber.

There are slightly different approaches to this. A basal cutting may be removed with a tiny sliver of tissue from the crown, while a softwood cutting can be trimmed immediately below a leaf node.

Work carefully. You want the cutting, not half the crown.

If possible, leave viable growing tissue on the mother tuber so that it can produce another shoot. Do not keep cutting blindly into the crown, as this is where the eyes and future growth are held.

Clean your blade between varieties and especially between plants. This helps reduce the risk of carrying disease from one dahlia to another.

Step 04 / Preparing Prepare the cutting

Once the shoot has been removed:

1. Trim the base cleanly just below a node if necessary.
2. Remove the lowest pair of leaves.
3. Leave the upper leaves intact.
4. If the remaining leaves are very large, reduce their surface area slightly.
5. Dip the base into rooting hormone if you use it.

Removing the lower leaves creates a clean section of stem to insert into the propagation medium.

Do not strip away every leaf. The cutting still needs foliage to photosynthesise, but it cannot support an excessive amount of leaf growth before it has roots.

Step 05 / Potting Pot the cutting

Fill a small pot or cell with clean, lightly moistened propagation medium.

I prefer a mixture that holds enough moisture to prevent the cutting from drying out while still allowing plenty of air around the developing roots. A fine propagation mix amended with perlite can work well. I have also propagated in only perlite before and added kelp meal to the cuttings and they grew beautifully.

Use a dibber or pencil to make the planting hole. This prevents the rooting hormone and delicate stem tissue from being scraped off as you insert the cutting.

Place the cutting deeply enough for at least one lower node to sit beneath the surface. Firm the medium gently around the stem.

Label it immediately with:

• Variety name
• Date taken
• Source plant, where relevant

Step 06 / Rooting Create the right rooting conditions

Fresh cuttings lose moisture through their leaves before they have roots to replace it.

They need:

• Bright, indirect light
• Warm but not excessively hot conditions
• High humidity
• Lightly moist growing medium
• Good airflow
• Protection from strong wind and direct midday sun

A propagation dome can help retain humidity, but it should not become a sealed swamp. Lift or vent the cover regularly and remove heavy condensation where necessary.

Too little humidity can cause the cutting to collapse. Too much moisture with no airflow can encourage fungal problems and stem rot.

The medium should feel lightly moist, never waterlogged.

How long do dahlia cuttings take to root?

Under good conditions, you may see the first signs of rooting within two to four weeks.

Look for:

• Fresh new growth at the tip
• Leaves remaining firm without constant misting
• Gentle resistance when the cutting is lightly tugged
• Fine roots becoming visible around the edge or base of the container

Do not repeatedly pull the cutting out to check. Roots are not improved by regular inspections and emotional support.

Some varieties root faster than others. A cutting that takes longer is not automatically a failure, provided the stem remains healthy and firm.

Step 07 / Acclimatisation Acclimatise the rooted cutting

Once the cutting has formed a healthy root system, gradually reduce the humidity around it.

Begin by opening the dome for longer periods. Then remove the cover completely once the plant can remain firm without wilting.

Move the rooted cutting into a slightly larger pot if needed and allow it to establish before planting it into the garden.

Do not move a cutting directly from a protected propagation space into full Pretoria sun. Harden it off gradually over several days by introducing it to:

• More air movement
• Brighter light
• Short periods of morning sun
• Outdoor temperature changes

Increase the exposure a little each day.

Step 08 / Planting Plant it into the garden

Plant rooted cuttings outside once:

• Frost danger has passed
• The soil is warm
• The plant has a healthy root system
• The cutting has been hardened off
• The planting bed drains freely

Handle the root ball gently and plant at approximately the same level it was growing in its pot.

Install support early. A cutting may begin as a very small plant, but it still intends to become a full-sized dahlia with absolutely no respect for the weather forecast.

Water it in gently and keep the soil consistently moist while the roots establish. Avoid leaving the young plant in saturated soil.

Can you use the tip removed when pinching a dahlia?

Yes, if the tip is healthy and long enough to prepare as a cutting.

When pinching a young dahlia, remove the growing tip above a leaf node to encourage the original plant to branch.

Instead of discarding the tip:

1. Remove its lower leaves.
2. Trim beneath a node.
3. Insert it into clean propagation medium.
4. Keep it warm, humid and out of direct sun.
5. Watch for new growth and root development.

Not every pinched tip will root, but it is useful material for practising your propagation technique.

The original plant branches, and the removed tip may become another plant. This is the sort of garden maths I fully support.

Common dahlia-cutting mistakes

Most cutting problems come down to the health of the material, moisture, light or airflow.

Will a dahlia cutting make tubers?

A healthy cutting can produce tubers during its first growing season.

The size of the tuber clump will depend on:

• How early the cutting was rooted
• The length of the growing season
• Plant health
• Soil conditions
• Watering and feeding
• The natural habit of the variety

A later cutting may produce a smaller clump, but it can still become valuable planting stock for the following season.

When the plant flowers, confirm that it is correctly labelled and producing the expected bloom. Photograph the flower with its label and keep notes on its performance.

My final dahlia-cutting checklist

One tuber can become the beginning of a collection

Taking dahlia cuttings is part skill, part observation and part courage.

The first cut is the hardest. After that, you begin to understand how generously a healthy dahlia can respond.

One precious tuber can give you a mother plant, several rooted cuttings and, by the end of the season, multiple new tuber clumps for the following year.

Start with one or two cuttings. Watch their moisture, learn how they respond in your conditions and adjust your method as you go.

If you try this at home, tag Femme Pétale in your propagation progress. I would love to see the varieties you are multiplying.

For more detailed guidance on planting, pinching, supporting, harvesting, dividing and storing dahlias, explore my Uncovering Dahlias guide and the complete Dahlia Growing Calendar for South African Gardens on the Femme Pétale website.