Planting Trees, Shrubs and Smaller Plants

Introduction

Planting is one of the most basic horticultural operations, but it is surprisingly easy to get wrong.

A plant can be:

the right species
healthy when purchased
planted in the right season

and still fail because it has been planted:

too deeply
too shallowly
in compacted soil
without sufficient water
with damaged roots
with the wrong stake arrangement
without adequate aftercare

Planting is therefore not simply:

Dig a hole → put plant in → fill hole.

It is about creating the conditions in which roots can establish.

The basic principle is:

The aim of planting is to establish a healthy root system, not simply to put a plant in the ground.

Before Planting

Before digging, check:

The plant

Is it healthy?
Is it correctly identified?
Is the root system healthy?
Is it pot-bound?
Is the plant damaged?

The site

Is the soil suitable?
Is drainage adequate?
Is the light appropriate?
Is there enough space?
Are there underground services?
Will the plant eventually become too large?

The weather

Avoid planting into:

frozen soil
waterlogged soil
excessively dry soil
very hot conditions

The soil should be workable rather than wet and smeared.

Bare-Root, Container-Grown and Root-Balled Plants

The planting technique varies according to how the plant has been supplied.

Bare-root

The roots are exposed and not contained in compost.

Often planted during the dormant season.

Container-grown

The plant has been grown in a pot or container.

Can often be planted over a longer season if conditions are suitable and aftercare is provided.

Root-balled

The roots and surrounding soil are lifted together, often with a supporting material around the root ball.

Commonly used for larger trees and shrubs.

The Planting Hole

The hole should generally be:

wider than the root system

rather than simply extremely deep.

The sides and base of the hole should allow roots to grow out into the surrounding soil.

Avoid creating a deep hole filled with loose soil into which the plant can sink.

How Deep Should a Plant Be Planted?

This is one of the most important questions.

A plant should generally be planted at approximately the same depth at which it was previously growing.

For a tree, look carefully for the:

root flare

or:

root collar

This is where the trunk begins to broaden as the major roots emerge.

The root flare should generally remain visible.

Planting Too Deep

Planting too deeply can cause serious problems.

It can:

restrict oxygen around the stem
encourage stem decay
interfere with root function
encourage poor root development
weaken the plant
eventually contribute to tree failure

One of the most common mistakes when planting trees is:

burying the stem too deeply.

Planting Too Shallow

Planting too shallowly can also cause problems.

The plant may:

dry out rapidly
have exposed roots
become unstable
suffer root damage

The answer is not simply:

“Plant everything shallow.”

It is:

Plant at the correct depth for that plant.

Backfilling the Hole

The excavated soil can often be used to backfill the planting hole if it is suitable.

Avoid automatically filling the hole with rich compost or imported soil.

Why?

Because roots need to grow out from the planting hole into the surrounding soil.

If the planting hole contains very different material from the surrounding soil, roots may be reluctant to move beyond it.

The aim is to create:

a transition between the plant and the existing soil.

Should We Add Compost?

Compost or organic matter may be appropriate where soil needs improvement.

However:

more compost is not always better.

Consider:

soil type
organic matter level
plant requirements
soil structure
drainage

Organic matter is particularly useful where it genuinely improves the soil.

It should not simply be treated as a universal planting ingredient.

Should We Tease Out the Roots?

This depends on the plant and root condition.

A container-grown plant may have roots that have begun to circle around the inside of the pot.

These can be:

gently loosened
teased out
redirected

where appropriate.

The aim is to encourage roots to grow into the surrounding soil.

Root-Bound Plants

A severely root-bound plant may have:

dense circling roots
roots growing around the pot
little visible growing medium
restricted root development

If left untreated, roots may continue growing in circles after planting.

This is particularly important with trees and shrubs.

Should We Cut Roots?

Do not automatically cut roots.

Unnecessary root damage can:

reduce the plant’s ability to absorb water
increase transplant stress
create wounds
reduce establishment

Remove:

dead roots
badly damaged roots
unsuitable severely circling roots where necessary

but retain as much healthy root as possible.

Planting a Small Plant

For a small herbaceous plant:

Prepare the soil.
Dig a suitable hole.
Remove the plant from its container.
Check the roots.
Gently loosen congested roots if necessary.
Position at the correct depth.
Backfill.
Firm gently.
Water thoroughly.
Provide appropriate aftercare.

Smaller plants generally establish more quickly than large plants because they have a smaller root system to support.

Planting a Shrub

Shrubs require greater consideration of their eventual size.

Before planting:

Look at the mature dimensions.

A shrub that looks small in a 3-litre pot may eventually occupy several square metres.

The planting process is generally:

Prepare the site.
Dig a suitable hole.
Check the roots.
Position correctly.
Check planting depth.
Backfill.
Firm.
Water.
Mulch where appropriate.
Monitor during establishment.

Planting a Tree

Trees require particular care because they may remain in the landscape for decades.

Before planting, consider:

final height
canopy spread
root space
buildings
roads
overhead services
underground services
drainage
soil
future maintenance

A mistake made during tree planting can remain visible for generations.

Tree Root Flare

When planting a tree, find the point where the trunk begins to flare outward into the roots.

This is the:

root flare

It should generally be at or slightly above the surrounding finished soil level.

Do not bury the root flare.

If it is difficult to find because the tree has been planted too deeply in its container, carefully remove excess growing medium from the top of the root ball where appropriate.

Tree Staking

Young trees may need support after planting.

The purpose of a stake is not necessarily to hold the tree rigid.

The tree needs to be able to move.

Movement can encourage the development of a stronger trunk and root system.

Therefore:

A stake should support the tree, not imprison it.

Where Should the Stake Go?

For many newly planted trees, a low stake is appropriate.

The stake is normally positioned so that the tree can move naturally above the point of attachment.

A common arrangement is:

stake + flexible tie + tree

The exact position depends on:

tree size
root-ball type
exposure
soil
tree form
local practice

Does It Matter Which Side the Stake Goes?

Yes, it can.

The stake should be positioned to provide effective support while avoiding damage to:

the trunk
root system
branches

The stake should not rub against the trunk.

Where prevailing winds are significant, positioning and tying should be considered so that the support protects the tree without preventing useful movement.

There is no universal rule that:

“the stake must always go on the north side.”

Good staking is about:

support + movement + protection.

Common Staking Mistakes

Avoid:

tying the tree rigidly
using a tie that cuts into the trunk
leaving ties on indefinitely
damaging the root ball
placing the stake where it damages major roots
using a stake simply because “trees always need stakes”

Some trees establish successfully without staking in sheltered situations.

When Should a Tree Be Staked?

Consider staking when:

the site is exposed
the tree has a large crown
the root system is limited
the tree has been root-balled
the tree is unstable
there is a risk of wind rock

A sheltered small tree with a good root system may not always require permanent support.

Watering In

In most situations, a newly planted tree, shrub or small plant should be:

watered thoroughly after planting.

This helps:

settle the soil around the roots
remove large air pockets
provide moisture for establishment
encourage contact between roots and soil

This is commonly described as watering in.

Why Watering In Matters

Even when the soil appears moist, planting can create gaps around the root system.

Watering helps settle the soil.

However:

watering in does not mean keeping the plant permanently waterlogged.

The plant needs:

water
oxygen
healthy soil pores

Too much water can be just as damaging as too little.

Watering After Planting

The first few weeks and months can be critical.

Newly planted plants have a limited established root system.

They may require additional watering during:

dry weather
hot weather
drought
windy conditions

The exact amount depends on:

plant size
soil
weather
season
rainfall
species
site exposure

Water the Root Zone

Water should reach the root zone rather than simply wetting the foliage.

A slow, thorough application is often more useful than a quick splash.

Check the soil.

Do not water automatically just because the calendar says:

“Water today.”

Should We Feed After Planting?

Usually:

do not automatically feed a newly planted plant.

The immediate priority is:

root establishment.

High levels of readily available nutrients can encourage excessive top growth before the root system has established properly.

Many soils already contain sufficient nutrients.

When Might Feeding Be Appropriate?

A soil test may indicate a nutrient deficiency.

Feeding may also be appropriate where:

the soil is genuinely deficient
the plant has particular nutrient requirements
the planting situation requires it

But feeding should be based on:

need

rather than:

habit.

Fertiliser Is Not Plant Food

The phrase:

“plant food”

is common in gardening.

Plants manufacture their own food through:

photosynthesis.

Fertilisers provide mineral nutrients.

These include N (nitrogen), P (phosphorus), K (potassium) and other essential elements. A useful horticultural habit is therefore to think:

“Does this plant need nutrients?” rather than “Should I give it food?”

Should We Mulch?

Mulching can be very useful after planting.

A suitable organic mulch can:

reduce evaporation
suppress weeds
protect the soil surface
add organic matter over time
moderate soil temperature

However, mulch must be applied correctly.

The Mulch Donut

One of the most important rules is:

Keep mulch away from the stem or trunk.

Do not create a mulch volcano around the base of a tree.

Instead create a mulch doughnut. The trunk should remain visible.

Why Not Mulch Against the Trunk?

Constantly wet organic material against the stem can contribute to:

decay
disease
pest problems
bark damage

The root zone can be mulched.

The stem should not be buried.

How Much Mulch?

A suitable mulch layer is often around:

5–7.5 cm

depending on the material and situation.

Avoid excessively deep mulch.

Very deep mulch can:

restrict oxygen
alter soil conditions
encourage shallow rooting
create problems around stems

What Can Be Used as Mulch?

Possible materials include:

well-rotted garden compost
well-rotted manure where appropriate
wood chip
bark-based materials
leaf mould

The material should be suitable for the planting situation.

Avoid using contaminated or immature material.

Mulching and Sustainability

Mulching can reduce:

watering requirements
weed competition
soil disturbance

It can also make use of locally produced organic materials.

However, mulch is not automatically sustainable.

Consider:

where it came from
how far it travelled
how it was produced
whether it was a waste product
whether its use is appropriate for the site

Planting Checklist

Before leaving the plant, check:

☐ Correct plant

☐ Correct location

☐ Correct depth

☐ Root flare visible where appropriate

☐ Roots healthy

☐ Circling roots addressed where necessary

☐ Soil firmed appropriately

☐ Plant stable

☐ Stake appropriate if required

☐ Tie flexible and not damaging

☐ Watered in

☐ Mulched if appropriate

☐ Mulch kept away from stem/trunk

☐ Aftercare arranged

Tree, Shrub and Small Plant: What’s Different?

Small plant	Shrub	Tree
Smaller root system	Larger root system	Potentially very large root system
Usually establishes quickly	Requires consideration of mature size	Long-term structural investment
Rarely requires staking	Usually does not require staking	May require staking
Watering important	Watering important	Watering particularly important during establishment
Usually little structural concern	Mature spread important	Root flare and future canopy critical
Mulching useful	Mulching useful	Mulching often useful
Usually easy to move	More difficult to move	Difficult and potentially expensive to move

Common Planting Mistakes

Planting too deeply

One of the most serious errors.

Digging a hole that is too narrow

Roots need room to spread sideways.

Breaking up the surrounding soil poorly

Roots need to be able to move into the existing soil.

Ignoring circling roots

Can lead to poor root development.

Over-fertilising

Can encourage inappropriate growth and damage roots.

Forgetting to water

New plants can fail quickly in dry conditions.

Overwatering

Roots also require oxygen.

Mulching against stems

Can encourage decay and other problems.

Over-staking

Can prevent natural movement.

Leaving ties on too long

Can damage the developing trunk.

The Planting Decision Tree

Before planting:

Is the plant healthy?

↓

Is the site suitable?

↓

Is the soil workable?

↓

Is the planting depth correct?

↓

Are the roots healthy?

↓

Does the plant need staking?

↓

Does it need watering in?

↓

Would mulch be beneficial?

↓

Does it actually need fertiliser?

↓

What aftercare will it require?

Practical Exercise

Plant one:

small plant

one:

shrub

and, where appropriate and supervised:

tree

For each plant record:

Plant name

Plant type

☐ Small plant

☐ Shrub

☐ Tree

Planting depth

Root condition

Was root teasing necessary?

☐ Yes ☐ No

Why?

Was staking necessary?

☐ Yes ☐ No

Why?

Was the plant watered in?

☐ Yes ☐ No

Why?

Was mulch applied?

☐ Yes ☐ No

Why?

Was fertiliser applied?

☐ Yes ☐ No

Why?

Student Questions

1. Why should a plant generally be planted at the same depth at which it was previously growing?

2. What is a tree’s root flare?

3. Why can planting a tree too deeply cause problems?

4. Why might the roots of a container-grown plant need to be teased out?

5. Should every root be cut when planting?

6. Why might a newly planted tree require a stake?

7. Where should a tree stake be positioned?

8. Should a stake prevent all movement of the tree?

9. Why do we water plants in after planting?

10. Why should we not automatically fertilise a newly planted plant?

11. What is the purpose of mulch?

12. Why should mulch not touch the trunk of a tree?

13. What is meant by a “mulch volcano”?

14. Give three signs that a newly planted plant may be suffering from poor establishment.

Remember

Planting is about establishment, not simply positioning.

Do not plant too deeply.

Check the root flare of trees.

Tease out congested roots where appropriate, but avoid unnecessary root damage.

Not every tree needs a stake.

A stake should support the tree while allowing appropriate movement.

The position of the stake matters because it must avoid damaging roots and the trunk.

Water newly planted plants in thoroughly, then monitor them.

Do not automatically fertilise after planting.

Feed because there is a demonstrated need, not because the plant has just been planted.

Mulch can be valuable, but keep it away from the stem or trunk.

And perhaps the most important rule:

A plant is not established when it has been planted. It is established when its roots have successfully colonised the surrounding soil.

The job of the horticulturist is therefore not finished when the spade goes back in the shed.

It has only just begun.

Key references

Royal Horticultural Society (RHS), guidance on planting trees and shrubs, staking, watering, mulching and plant establishment.
Royal Horticultural Society (RHS), guidance on soil preparation and planting.
Forestry Commission, guidance on tree planting and establishment.
BS 8545, Trees: from nursery to independence in the landscape – Recommendations.
BS 4428, Code of practice for general landscape operations (excluding hard surfaces).
International Society of Arboriculture (ISA), guidance on tree establishment, root systems and staking.
Department for Environment, Food & Rural Affairs (Defra), guidance relating to trees, soils and sustainable horticultural practice.