GROWING
PLANTS
SUMMARY
NOTES
P.McCaughan
Growing Plants from Seeds
Seed Biology
-
Seeds are used by a plant to
-
All seeds have an embryo,
food store and a seed coat
Germination:
Look for:
reproduce itself
 Dormancy

Germination
 Temperature
 Oxygen
A growing seed
 Moisture
-
-
Photosynthesis
Plants use sunlight to make
for themselves

Plants use CO2 (Carbon dioxide)
and release O2 (Oxygen).
Photosynthesis
Growing plants from seeds:
food

Germination is when the embryo grows into a
new plant. It uses its food store until the first
leaves can begin photosynthesis and the plant can
produce its own food.
Before it can germinate the seed needs the
correct temperature, oxygen and moisture.
Dormancy is when the seed lies dormant in the
soil. The seed will wait until it has the correct
conditions (above) before it germinates.
Seeds come in many different sizes and
some are easier to germinate than others.
How you should sow a seed depends upon
its size:
Large
seeds
Small seeds
Pelleted
seeds
Are sown
individually
Are sown mixed with silver sand
Coated with three layers:
pesticide, fungicide and nutrients.
Pregerminated Are soaked in water or nicked
(chitted)
seeds
Test yourself:
 What is photosynthesis?
 What are the three layers in a pelleted
seed?
 Why are seeds chitted?
 What do you mix small seeds
with before planting?
to speed up
germination
Vegetative propagation
Vegetative propagation means to reproduce plants
(without using seeds) using the natural methods
that the plant uses.
Natural
structures
Examples
Natural food
storage
organs
Bulbs
Daffodil, Onions,
Tulips
Tubers
Potato
Natural
attached
offspring
Runners
Offsets
Spider Plant
Plantlets
Mexican Hat Plant
Cacti
Artificial propagation
Artificial propagation means to reproduce the plant
(without using seeds) using methods that the plant
itself is unable to carry out.
Facts to know:
- If a plant is wounded it must grow to heal itself.
- Nodes are places on the plant where the
braches and leaves come out from the stem. A
node is a point of growth and usually where we
wound the plant when taking a cutting.
- Rooting powders contain chemicals
Look for:

Storage organs


Cuttings
Layering
 Attached offspring
 Nodes
(hormones) which cause roots to develop at a
wound.
Cuttings
Layering
Methods of Artificial Propagation
The plant is cut off below the node and
placed in moist soil at a suitable temperature
(not freezing). The ‘cutting’ then develops
roots and grows into a new plant.
A stem of the plant, between two nodes is
wounded and dipped in rooting powder.
It is then pegged to the soil and roots will
develop. Later the stem is cut and you have
two plants.
Cuttings
Propagator
The advantages of layering
-
large healthy plants that are more likely to survive.
The plants don’t need nursing; they remain attached to the parent
It produces
plant.
- Good for plants that are difficult to grow from cuttings e.g.
Rhododendron
Propagators
Water loss can be reduced by using a propagator. A propagator is a piece of
equipment that is used to provide a moist and warm environment for the plants. It can be as simple as a
plastic bottle or as complicated as a mist propagator, which sprays fine mists on the plants and warms the
soil below them. Glasshouses are examples of propagators.
Methods of reducing water loss
-
leaf surface area (number of leaves)
by removing the lower leaves.
Put the cutting in a propagator or moist environment.
Increase the humidity.
Reducing the
The pros and cons of heating
Pros (good)
-
-
constant suitable
temperature 24 hrs a
A
day encourages the fast
production of roots
Great during the winter
months as the plants are
protected from the
Cons (bad)
-
The hotter the temperature the more
water the plant will lose causing them to
-
dry out, wilt and die.
The warm moist conditions can causes
-
to develop on the plant.
The extra energy used to heat the
frosts.
Soil holds less water than compost
grey mould
propagator costs
more money to run.
(On the next page)
Look for:
 growing medium
Test Yourself:
 Loam
 Peat
 Say out loud the definition
for nodes.
 Name a natural food storage
organ and give an example.
 Perlite

What are the three conditions
of germination?
 How can you promote root
growth in a cutting?
Plant
Production
 Give two advantages
of layering.
 What is one difference
between natural and artificial
propagation?
Conditions for plant growth
 Plants need to be planted in a growing medium that provides
them with water and nutrients through the roots. The roots also need oxygen for respiration so
the ‘growing medium’ needs to have air spaces in it as well.

We use compost in artificial conditions (pot plants) because the roots can’t spread out as
much and the natural soil couldn’t hold enough water or nutrients for the plant, because there is
less of it in a pot.
Compost
Composts are made from different materials to provide
the potted plant with
Material
Loam (good
garden soil)
Peat
Peat substitutes
Grit and sand
Perlite
Fertiliser
everything it needs in a small space.
Property
Provides nutrients and basic ‘dirt’
structure.
Allows the compost to hold more
water.
Same as for peat (above)
Increases the air spaces for the roots
and allows the water not held in the
peat to drain away so the plant doesn’t
drown.
Same as Grit and sand (above)
Increases the nutrients available to the
plant.
Information
Must be sterilised to kill insect pests,
weeds and micro-organisms (bacteria).
This is a non-renewable resource so
artificial peat may be used instead.
These are made from Cocoa shells, bark
and coir (hair from the coconut)
Quite large particles of sand are needed
because small particles block the air
spaces.
Made from small white volcanic minerals.
Contains Nitrogen (N), Phosphorus (P) and
Potassium (K). These three elements are
essential for plant growth.
Main Material
Loambased
compost
Sterilised
Other materials
loam
Sand
Nutrient
Loamless
compost
Peat
Sand
Fertilizer
Fertilizer
Peat
Importance of nutrient to
plant
Test
Chemical yourself:
Chemical
name
 What issymbol
peat used for?
 Name two
of using
heating.
Nitrogen
N advantages
Promotes
leaf
growth
Phosphorus
growth
 What isP anotherPromotes
word for root
loam?
 State out loud two disadvantages
of using
heating.
Promotes the growth
of flowers
Potassium
K
and fruit.
Fertilizers
A fertilizer with 1%
Potassium, 2%
Phosphorus and 4%
Nitrogen would have the
ratio 4:2:1
Look for:
 Fertilizer
 Nitrogen


Phosphorus
Potassium
 N:P:K

The mineral ratio is always referred to in the order

A fertilizer can be
applied as either a
N:P:K
powder, a liquid
or a granule.
Watering
Note: There are other
minerals such as Sodium,
Magnesium and Calcium,
which are also essential, but
they are needed in smaller
quantities.
We water plants so that they don’t dry out.
Plants need water so they can survive and grow.
Test yourself:

What are the three ways a
fertilizer can be applied?
 Name the main material in a
loamless compost.

Name two other minerals a
plant needs.
Watering by
hand
Automatic
watering
above
From
From
below
Trickle
irrigation
Capillary
matting
Water
retentive
gel



From a watering can
for most plants
For sensitive, delicate
plants.
Watering from above
using pipes with
adjustable nozzles.
A material that draws
water up to stay
moist.
A chemical that can
hold many times its
weight in water.
Things to watch for
Don’t allow the drainage saucer to
become too full.
Stand the tray in water for about
15 minutes.
Use when it is crucial that the plant
doesn’t miss a watering.
May need to supply thick pots with
a wick.
Usually added to compost.
Every plant has an optimum temperature that
it grows best in i.e. between 5-30 degrees Celsius.
If the temperature goes above or below this the
plant will suffer.
We can monitor the temperature using a
maximum/minimum thermometer.
We can control the temperature by putting the
plant in a
green house (A large propagator)
Look for next:
 Heating
 Humidity

Ventilation
Heating
Humidity


Humidity is the amount of water vapour in the air (how moist the air is).
We can measure the humidity by using a ‘wet and dry bulb hygrometer’
Test yourself:
Ventilation
 What are three
ways of
automatic
watering?
 What is the
simplest way to
ventilate plants?
 What are two
things to
watch for
when watering
by hand?
Ventilation is another way of controlling the
temperature around a plant. It can be as simple as
opening a window or we can use:
 Automatic vent openers
 Extractor fans

Thermostatic control
Wind speed can be measured using
a
wind meter.
Test Yourself :
season most seeds would be dormant through.

Name the

Name three minerals needed by plants in
smaller
quantities.
large grit and sand particles are needed in compost.
 What is humidity a measure of?
 What material does loamless peat not have in it?

Explain why

Give one

good point and one bad point about using heating in a propagator.
Describe two methods of reducing water loss in a propagator.
Describe one difference between artificial and natural propagation methods.

List the three conditions that are needed before

germination can occur.
 Why does a plant have seeds?
Plant Maintenance
Pot plants need to be put in a place where they receive the
Type of
plant
Where is grows in
nature
same conditions as they are used to in nature.
What they need
Cacti
In a sandy desert. Dry
and well drained.
Ferns
Under tall trees in
forests. Dim, cool, humid
and sheltered.
In woodlands which are
still quite brightly lit by
the sun, moist with very
nutrient rich soil.
On the edges of
woodlands and in
grasslands.
Foliage
plants.
Flowering
plants
Direct sunlight and well
drained soil. Warm
conditions in summer and
cool conditions in winter.
Humid cool conditions, out
of direct sunlight.
Out of direct sunlight,
moist but well drained soil
that is high in nutrients.
Lots of light, lots of water
and plenty of nutrients.
Look for:
 Cacti
 Ferns

 Flowering
plants
Methods of maintaining plants
What it is
Pricking
out
Potting
on
Dead
heading
Why you do it
Gives the growing seedlings
more space so they can
grow as fast as possible
without competing for
nutrients and light.
To prevent the plant from
becoming ‘root bound’ in a
pot that is too small.
To keep the plant producing
flowers.
Foliage and
How you do it
Using a spatula dig them out and put them in their
own pot
If the plant is growing slowly, uses water very
quickly or has roots growing out the bottom of the
pot you need to put it in a larger pot
Pulling off each flower as soon as it begins to die.
Controlling pests and diseases
Aphids
–
–
Suck the plants sap.
–
Biological control: Use
Chemical control: Use pesticide to kill them.
ladybirds to eat
them or soapy-water to wash them off.
Grey mould
-
Grows on the leaves.
Chemical control: Use a fungicide.
Biological control: Take the plant out to the
fresh air, pull off the infected leaves and
burn the
Protected cultivation
Plants can be damaged by:
 wind
 rain

frosts
Look for:

Damage
 Glass
 Plastic
They can be protected by shielding them under:
 Glass – Glasshouse.
 Plastic – Polytunnels

Man-made fibres –
Floating fleece.
Polytunnel
Test yourself:
 Name three ways you can shield plants from the elements.

What are the similarities between where a cactus grows and the conditions
needed for it to grow well in
a pot?

Name three environmental factors that can

Explain how pricking out is

Explain what the purpose is behind

damage plants.
different from potting on?
deadheading a plant?
Which of the two plants above will probably grow in a similar area?