Propagation by Division

What is propagation by division?

Propagation by division is a form of vegetative propagation in which an established plant is separated into two or more sections, with each section capable of continuing to grow as an independent plant.

Unlike propagation from seed, division does not involve sexual reproduction. The new plants are therefore normally genetically identical to the parent plant.

It is one of the simplest forms of propagation and is particularly useful for herbaceous perennials and plants that naturally produce several growing points.

The basic principle is:

One established plant → several smaller plants → several new plants

However, division is not simply a matter of pulling a plant apart.

The sections need to contain the structures required for continued growth.

Why divide plants?

There are several reasons why a gardener might propagate by division.

1. To produce new plants

A healthy established plant can provide several new plants relatively quickly.

2. To rejuvenate an overcrowded plant

Some perennials become congested as they age.

The centre of the plant may become less vigorous while younger growth develops around the outside.

Dividing the plant can restore vigour.

3. To control size

A plant may have become too large for its position.

Division allows the gardener to reduce the size of the original plant while creating additional plants.

4. To maintain plant characteristics

Because division is vegetative propagation, the new plants retain the characteristics of the parent plant.

5. To improve flowering

Some overcrowded perennials may flower less effectively.

Dividing and replanting healthy sections can give the plants more space and resources.

Which Plants Can Be Divided?

Division works best with plants that naturally produce multiple growing points.

Suitable examples include:

Hemerocallis
Iris
Hosta
Astilbe
Rudbeckia
Phlox
Asters
many herbaceous perennials
ornamental grasses
some ferns
some bulbs and bulbous plants

Not every plant should be divided.

Plants with a single central growing point or a delicate root system may be better propagated by another method.

Know the plant before you divide it.

What Does Each Division Need?

This is one of the most important principles.

A successful division normally needs:

Roots + shoots/buds + growing point

The exact requirement varies between plant types.

If a section contains roots but no viable growing point, it may fail to produce new shoots.

If it contains a shoot but insufficient roots, it may struggle to establish.

The gardener is therefore trying to create balanced divisions.

Types of Division

There are several ways to divide plants depending on their structure.

1. Pulling Apart

Some plants naturally produce separate crowns or offsets.

These can sometimes be carefully pulled apart by hand.

This is one of the least damaging methods because the natural separation points are already present.

2. Cutting Through the Crown

A congested crown can be divided using:

a sharp knife
spade
border spade
specialist dividing tool

Each section should contain sufficient roots and viable shoots.

The cut should be clean rather than repeatedly hacking through the plant.

3. Splitting with a Spade

Large, tough perennial clumps can sometimes be divided using a spade.

The spade is driven through the crown to separate sections.

This can be effective for robust plants but requires care.

The objective is not simply to make the plant smaller.

It is to produce healthy, viable sections.

When Should Plants Be Divided?

Timing depends on the plant.

For many herbaceous perennials, division is carried out during periods when the plant is not under severe stress.

Two common periods are:

Spring

Spring division allows new divisions to establish during the growing season.

This can be particularly useful for plants that are beginning active growth.

Early autumn

Early autumn can also be suitable because the soil may still be warm while temperatures are cooler and moisture levels are often more reliable.

The exact timing should always be checked for the individual plant.

Avoid dividing plants during periods of:

extreme heat
drought
waterlogging
severe frost

The principle is:

Divide when the plant can recover quickly.

The Basic Division Process

Step 1 — Identify the plant

Check that the plant is suitable for division.

Step 2 — Choose a healthy parent plant

Avoid plants showing obvious disease, pest problems or severe stress.

Step 3 — Prepare the new planting area

Do this before dividing the parent plant.

The divisions should not be left exposed while the gardener prepares the soil.

Step 4 — Lift the plant

Use a fork or spade to loosen the soil around the plant.

Try to preserve as much of the root system as possible.

Step 5 — Remove excess soil

Gently remove enough soil to see the structure of the crown and roots.

Step 6 — Identify natural divisions

Look for:

crowns
buds
shoots
offsets
natural gaps

Step 7 — Separate the plant

Pull, cut or split the plant according to its structure.

Step 8 — Check each division

Each section should have enough healthy roots and viable shoots.

Step 9 — Replant immediately

Plant divisions at the correct depth.

Do not leave roots exposed to drying winds or strong sunlight.

Step 10 — Water thoroughly

Water the new plants in to settle the soil around the roots.

Step 11 — Label if required

Record the plant and date of division.

The Importance of Roots

When a plant is divided, its root system is reduced.

This creates a temporary imbalance:

Fewer roots → less water absorption

while the remaining leaves may continue to lose water through transpiration.

This is why newly divided plants can wilt.

The gardener can reduce this stress by:

dividing at the appropriate time
retaining sufficient roots
reducing excessive foliage where appropriate
replanting quickly
watering thoroughly
protecting the plants from excessive drying

Division and Plant Biology

Division works because plants contain growing tissues capable of producing new roots and shoots.

The meristematic tissues at growing points contain actively dividing cells.

When a plant is divided correctly, these growing points remain connected to sufficient roots and can continue development.

The gardener is therefore not creating a new plant from nothing.

They are reorganising an existing plant into several viable growing units.

Division Compared with Other Propagation Methods

Method	Material used	Main advantage
Seed	Seed	Genetic variation and large numbers
Hardwood cutting	Mature woody stem	Simple and inexpensive
Softwood cutting	Young stem	Often rapid rooting
Semi-ripe cutting	Partially mature stem	Useful compromise between soft and woody material
Leaf cutting	Leaf tissue	Useful for particular ornamental plants
Petiole cutting	Leaf stalk	Useful for selected plants
Division	Crown, roots and shoots	Rapid establishment of established plants

Division has one major advantage over many cuttings:

The new division already has a functioning root system.

This can allow it to establish relatively quickly.

Division vs Splitting

Students often use the words interchangeably, but there is a useful distinction.

Division

The plant is separated into natural or manageable sections, often preserving individual crowns or growing points.

Splitting

A tougher clump may be physically cut or split into sections.

Both methods are forms of division, but the amount of force and damage involved can differ considerably.

The gardener should always use the least damaging method suitable for the plant.

PPE and Health & Safety

Division involves tools, heavy plants and manual handling.

Activity	Hazard	Control / PPE
Lifting plants	Back strain or manual-handling injury	Assess weight; use correct lifting technique; team lift where appropriate
Using a spade	Cuts or foot injuries	Safety footwear; correct technique
Cutting crowns	Cuts	Gloves; use suitable sharp tools correctly
Handling roots	Splinters, sharp material or irritants	Suitable gloves
Working with soil	Dust and microorganisms	Gloves; avoid unnecessary dust
Moving large plants	Crush injuries	Assess weight; use appropriate lifting equipment
Wet ground	Slips	Suitable footwear and good housekeeping

A sharp tool is generally safer than a blunt one because it requires less force, but it must still be handled correctly.

Common Mistakes

Dividing the wrong plant

Not every perennial responds well to division.

Dividing a weak plant

A stressed or diseased parent plant is poor propagation material.

Making divisions too small

Tiny sections may lack sufficient roots or shoots.

Leaving roots exposed

Roots can dry surprisingly quickly.

Dividing during extreme weather

Heat, drought and frost increase stress.

Damaging the crown unnecessarily

Repeated hacking can create unnecessary wounds.

Planting too deeply

The crown of many herbaceous plants should not be buried excessively.

Forgetting to water

Newly divided plants require attention while their root systems re-establish.

Signs of a Good Division

A good division should have:

☐ Healthy roots

☐ One or more viable growing points

☐ Adequate foliage or buds

☐ No obvious disease

☐ A reasonable balance between roots and shoots

☐ A suitable size for establishment

The aim is not to produce the largest number of pieces.

The aim is to produce the largest number of viable plants.

Practical Activity

Dividing an Established Herbaceous Perennial

Plant: ______________________________

Date: ______________________________

Reason for division: ______________________________

Number of divisions produced: _____________________

Number of viable divisions: ________________________

Tools used: ______________________________________

PPE used: ________________________________________

Method: Pulled apart / Knife / Spade / Other

Condition of parent plant: _________________________

Examine One Division

Number of shoots/buds: ____________________________

Root condition: ___________________________________

Approximate root size: ______________________________

Foliage retained: __________________________________

Planting depth: ___________________________________

Watering carried out: Yes / No

Student Questions

1. Why is division a form of vegetative propagation?

2. What should a successful division contain?

3. Why might division rejuvenate an old perennial?

4. Why should plants not normally be divided during extreme heat?

5. Why is it important to prepare the new planting area before lifting the parent plant?

6. What is the advantage of division compared with growing a plant from seed?

7. Why might a division wilt after planting?

Remember

Division is one of the simplest propagation techniques, but simplicity does not mean carelessness.

The gardener needs to understand the plant’s structure and recognise where its roots, crowns and growing points are.

The objective is not:

“How many pieces can I make?”

It is:

“How many healthy plants can I produce?”

A good division contains enough root to support the shoots and enough viable growing tissue to continue producing new growth.

Lift carefully. Look closely. Divide intelligently. Replant quickly.

That is the essence of successful propagation by division.

Key references

Royal Horticultural Society (RHS), guidance on dividing herbaceous perennials and propagation.
Toogood, A. (ed.), RHS Propagating Plants.
Hartmann, H.T. et al., Plant Propagation: Principles and Practices.
Taiz, L. et al., Plant Physiology and Development.
Health and Safety Executive (HSE), guidance on safe use of hand tools and manual handling.