Nursery Production
Methods and their Impact
on Transplanting Success
Keith Sacre, Sales Director
Barcham Trees PLC
Keith Sacre, Barcham Trees PLC
We are all familiar with the
following in our Streets
And a few more............
And a few more............
Nearly there............
Plane Tree in Whitehall
Trees in Towns II
“Average loss rate of 23% for newly planted
highway trees and 24% loss rate for newly
planted trees in public open spaces”
If this statistic is accurate large proportions of
resources are being wasted
What is specified and
what is omitted ?
Co-dominance
lack of stem
taper
1.8 meter clear
Stem
Good straight
leader
Perhaps!!!
Central Leader
Production system
3 primary systems used in the UK
Bare-root
Root-balled
Container grown
Bare Root
Advantages

Investment per plant is low

Cost of plants to the consumer is low

Plants are lightweight, making shipping
economical
Bare-root
Bare Root
Disadvantages

Planting time for digging and transplanting is short

Only deciduous species easy to transport are
suitable

No root activity occurs until bud swell in the spring

Larger plants have a higher mortality and the
survivors are slow to recover

Plants need to be stress tolerant and capable of
rapid root regeneration following transplantation
Bare root species
selection

Trees with Fibrous root systems transplant better than those with
coarse roots

Fraxinus excelsior, Prunus avium, Sorbus aucuparia and Acer
platanoides have fibrous root systems

Quercus robur, Carpinus betulus and Fagus sylvatica have
coarse root systems

Fibrous roots are suggested to be more prone to desiccation in
the period between lifting and planting (SPECIFIABLE)
(Struve, 1990)
‘The Planting of Trees and Shrubs’
(Watson & Himelick, 1997)
Suggests evidence of lateral root development is
a good indicator of plant health in bare root trees
(SPECIFIABLE)
 Stock with strong tap roots and little lateral
development are unlikely to survive
(SPECIFIABLE)
 Guideline indicator: Root spread should equal 4
x’s the stem circumference
(SPECIFIABLE)

Rootballed
Advantages

Digging and transplanting season is extended
compared to Bare root (BR)

Plants with poor survival rate as BR can be
transplanted with moderate success

Soil ball placed in the landscape creates minimal
textural and water movement barriers

Plants can be dug ahead of time and stored above
ground, extending transplanting time
Rootballed
Disadvantages








98% or more of the root is lost at digging
Digging is limited to the dormant season for all but a few very
tolerant species
Some species cannot be transplanted with satisfactory survival
rates
Labour is intense and needs to be skilled
Soil type and moisture conditions can limit digging
Root balls are heavy and awkward to transport
They must be kept most, but not wet during handling and
shipping
Planting must be completed in the spring before natural bud
break for the species
98% of root system can be lost
when trees are dug from the
nursery using standard methods
Watson and Himelick (1997)
What is actually inside the Rootball?
Inside a Rootball ......
When planting rootballs
the following is true.
(MAINTENANCE:)

Can only absorb water from a soil that they
have proliferated

Water contained in soil outside the rootball is
largely unavailable

Root system must ‘grow into’ the soil outside
the rootball before water there is useful to the
plant
Root generation and
water uptake
(MAINTENANCE:)

Can take up to 7 weeks for new roots to be initiated following
digging

Up to 13 weeks before the regenerated roots are capable of
absorbing measurable amounts of water from outside the roortball

Up to 20 weeks until the soil moisture is absorbed at similar rates
from rootball and backfill soils

Water available to newly transplanted trees is only enough for a few
days at a time
Rootball production
The rootball system of
production evolved around
the principal of root pruning.
This system is often referred
to in nursery catalogues as
3 x transplanted.
(SPECIFIABLE)
This is rarely specified………..
Rootball
specification

Hartman et al (2000) produced a table outlining the
ideal rootball diameter and depth to enable
successful establishment

A tree of 14-16cm girth should be supplied with a
rootball of 70cm diameter and depth of 60cm
(SPECIFIABLE)

How many rootballs supplied into the market would
meet this specification?

Such a rootball would weigh 300lbs, an equivalent
85L 14-16cm container grown tree would weigh
198lbs
Rootball dimensions in relation
to tree size at purchase
Caliper (inches)
Rootball diameter
(inches)
Rootball Weight (lbs)
2
24
392
2.5
28
624
3
32
867
3.5
38
1216
4
42
1877
Watson & Himelick (1997)
Principles and Practice of Planting Trees and Shrubs
Rootballs in USA
Note
• Root balls stored upright
• Individually irrigated
• Position and height of wire
• Stem taper
Container Grown Trees
Advantages

The root system is entire and undamaged

The trees can be moved and planted at any time of
year, although less maintenance is required if they
are transplanted during the autumn and winter

Trees are generally easier to handle and store

Post transplanting stress and shock is reduced to a
minimum

Earlier aesthetic rewards are achieved in the
landscape
Container grown Trees
Disadvantages

It has been claimed that container trees require additional
irrigation during the establishment period

There are potential problems at the soil-compost interface

There is always the potential for root girdling within the container.
The length of time a tree spends in a container is critical. All
systems produce root girdling. At Barcham we have introduced a
concept which we call ‘shelf life’ (SPECIFIABLE)

It has been argued that container compost media contains none
of the naturally occurring mycorrhizal and bacterial elements to
the detriment to post transplanting establishment
What is never
specified?
?
Container Grown
Rootballed
?
Bare-root
Stem taper
Much nursery management is
comparable to woodland management
with trees closely spaced, elongated
with little of no stem taper.
Stem taper
Barcham Birch showing defined stem taper
Height: stem
diameter ratio
Where the tree as
actually grown
Many trees
supplied into the
UK market have
spent no more than
a few minutes on
the supplying
nursery as they are
transferred from
one lorry to another
(SPECIFIABLE)
Plant Health
All the above can be specified but none
actually ask the question as to whether the tree
is actually stress free at the time of supply.
•
It is a bit like buying a fridge by size and
colour without actually asking whether it works
or not.
•
Plant Health
Arboricultural Research and Information Note
126/94 Arb entitled ‘Assessing the Quality of
Broadleaved Nursery Stock’ stated:
“the early survival of trees in any planting is
determined largely by the quality of the planting
stock and post planting aftercare
However assessment of tree quality relies on
external morphological features”
Plant Health
It continues....
‘”many trees which meet the morphological
criteria are dead or moribund before planting”
Insley 1982
“Further work is aimed at developing a simple
easily determined PLANT QUALITY INDEX
for broadleaved planting stock that will reflect
the ability of plants to survive outplanting”
Plant Health
Up until now this has not happened.
BUT
Flourimeter
Spadmeter
Plant Health
In the Arboricultual Newsletter Issue 146 Autumn 2009
Dr Glynn Percival reviewed the following as plant
vitality tests which might be useful.
• Shoot and root electrolyte leakage
• Root growth potential
• Chlorophyll fluoresence
• Chlorophyll content
• Twig starch concentration
• Infra-red thermometery
Plant health
At Barcham we have tested over 15,000 trees
on the nursery
•
•
•
Chlorophyll fluorescence
Chlorophyll content
Electrolyte leakage (SPECIFIABLE)
This will provide a benchmark as to plant health
on the nursery and at the time of supply.
Specifications:
The future
From the above it is perhaps possible to visualise
specifications which will include in addition to girth and
clear stem.
• Production method and criteria to ensure that
method is being practised correctly
• Stem taper
• Height/ stem diameter ratio
• Production site
• Chlorophyll fluorescence
• Chlorophyll content
• Electrolyte leakage
• Length of time actually on supplying the nursery
Ultimately ……………
The Choice is yours
But asking the right questions
and preparing comprehensive
specifications may avoid in
the future the current ‘Trees
in Towns II statistics
What other industry would
accept a 25% failure rate as
the norm and survive?
Any Questions?
Thank you
for
listening.