Structures used to support
propagation activities
Glass house
Poly tunnel
Cold frame
Low poly tunnel
Malling bin
-others
Raised bed, outdoor seed beds
Micropropagation unit
Cold
frame
Use of cold frame
Use Sept- Oct, April and June-July for
vegetative propagation
Sept- October semi ripe cuttings inserted
with no heat with or without plastic cover
depending on species and transplanted in
the spring when rooted. Give protection and
irrigation as needed.
April root Juniper with plastic over them lift
and transplant in June
June insert many types of cutting to be
ready for lifting in September
Cold frames can also be used for
Germinating seeds
Hardening off plants
Hardening off and protecting bedding plants
Plunging bulbs for forcing
Multi-span polytunnel
Polytunnel may be equipped with
Fan assisted ventilation
Frost protection or heating source
Internal facilities for propagation
Useful for protection of more hardy plants,
hardening off and growing on
Useful for protection of herbaceous
perennials propagated by division
Shade tunnel also useful for protection and
growing on of hardy plants
Propagation Glasshouse utilizing fine mesh nozzles
on risers to prevent drip. Lighting and Bench Heat,
Plants may be propagated directly on open
benches or other specialist facilities may be
provided within the protected structure
Mist unit
Heated benches or floor
Humidity chamber
Fogging unit
Growth or propagation chamber (hot box)
Through the bench riser, providing misting /
irrigation, open bench floor to allow drainage,
shade or thermal screens, fan ventilation
Heated root zone
May be via hot water pipes set in
polystyrene trays (hard to relocate)
Or low voltage electric heat pads set in
flexible blanket Usually over polystyrene to
insulate and reduce heat loss (easier to
relocate)
Usually has water retentive surface
(capillary matting)
May be used with or without covers or mist
jets depending on plant requirements
Low bottom heat may also be used to
promote callus and rooting in specialised
cold frame
Some different ways of raising the
humidity levels for propagation
Humidity chambers
Closed case system
The simplest method is to use plastic over
hoops on a bench. May be heated or not.
Water vapour condensing on the inside of
the plastic helps to protect the cuttings
against desiccation
Soft cuttings may succumb to disease if the
plastic covering touches the leaves.
Shading required in excessively hot
conditions.
Humidity Chambers
Many variations on a theme
On benches in another structure see our
glass house
Over outdoor beds e.g. Semi-ripe
production of heather
Low tunnels outdoor
Inexpensive and simple Suitable for easily
propagated mass produced plants where margins
are tight
0.9 m wide tunnel of milky white plastic (500
gauge). Supported on low hoops, sealed at sides
and ends located directly on the soil.
Once plants are rooted and weaned they can be
left uncovered to grow on until transplanted
Irrigation, weed control and soil improvement
may be needed
E.g Escallonia cuttings inserted June/July. Leave
in bed until autumn. Transplant and grow on for
one more year
Mist units
These will be inside a protected structure
Keep up the humidity by use of water
droplets delivered through nozzles
Components of a mist unit
Bench or floor usually heated
Mist jets on riser to supply fine water spray
Electronic leaf to control humidity levels
Solenoid valve to control water flow to jets
Clean water source isolated from mains to
avoid contamination
Bottom heat thermostat controlled 21-24o C
Air temp 15 26o C
Clean soft water needed
Plants will need to be weaned off the bed
and accustomed to less humid conditions as
roots increase.
May be by reducing frequency of water
supply or use of weaning bed
Nozzles for irrigation and propagation
The spray is formed by
a stream of water
entering the nozzle and
being accelerated by
the cone shape of the
chamber before it is
ejected through the
orifice at high speed.
The droplet size
depends on the size of
the nozzle orifice and
the pressure
Advantages and disadvantages of
mist unit
allow slower rooting subjects time to root
without rotting off in the high humidity
conditions found under plastic.
keeps leaves cool
checks transpiration without the need for
shading is advantageous.
lime scale deposits a disadvantage
Keeping system clean to avoid waterbourne
diseases
Some plants with woolly leaves do not do
well in mist unit
Some plants respond better in mist unit e.g.
Ceanothus
Fogging units
Provide a humid atmosphere
Often in whole glasshouse section
Smaller water particles
Health and safety issue with legionella risk
Horizontal Airflow Fogger
Heated propagation units
self contained systems come in many sizes and fixed
temperature units or adjustable thermostats.
Warmth increases the rate of respiration resulting in
a faster rate of energy production.
optimum temperature dependant on species
Care must be taken to avoid damagingly high
temperatures in sunny weather.
Heated benches can be created through the use of
heating cables which can be run in a suitable
media under the seed trays
Heated propagation units
Because of the ability to control the
environment these may be particularly
useful for seeds requiring steady
temperatures.
Many half hardy seeds require 21-24 o C
Look for optimum temperatures when
raising from seed
Seeds may be germinated in open or closed
cases under protection which provide the
correct heat and conditions for the specific
plant type
Cold frames may also be used
Seeds of hardy plants may be sown
outdoors directly into the soil in seedbeds or
raised beds with or without a cover
Germination cabinets
Used to germinate seeds
Provide controlled temperature
With or without lighting
Light available via replacement lighting
after emergence
Not so easily affected by surrounding
temerature
Other uses for glasshouse in
propagation
Some plants benefit from being kept in a
glass house or under protection before and
after grafting.
E.g large flowered Rhododendron may be
kept around 13-16 O C after grafting to
promote healing
Other facilities
Stock beds
Tools and equipment
Pots and composts
Stratification pits
Cold stores and fridges
Stock beds
