Growing Plants
Technical & Teaching Notes
Related sheets
Plant nutrients; Making and testing nutrients; Homemade fertilisers
Introduction and context
This guidance is for the three student sheets: Soil culture • Water culture • Floating culture
Each of these sheets provides a protocol that may be used to investigate the growth of seedlings
and describes an investigation that students could carry out. The protocols can be used in other
investigations. The protocols could be used to help plan and carry related investigations for
example in the sheets Making and testing nutrients and Homemade fertilisers.
Safety Notes
In the quantities used the substances used are low hazards.
Equipment and materials
Growing solutions
Standard Sachs solutions are available, but a ‘complete-nutrient’ growing solution can be
prepared by dissolving the following compounds in 1 dm 3 of deionised water.
0.70 g KNO3
0.25 g CaH4(PO4)2.2H2O
0.25 g CaSO4.2H2O
0.25 g MgSO4.7H2O
0.08 g NaCl
Nutrient-deficient growing solutions can be prepared similarly, but with these changes:
Nutrient solution deficient in
Replace
With
Nitrogen
KNO3
0.52 g KCl
Phosphorus
CaH4(PO4)2.2H2O
0.16 g Ca(NO3)2.4H2O
Potassium
KNO3
0.59 g NaNO3
Calcium
CaSO4.2H2O
0.2 g K2SO4
CaH4(PO4)2.2H2O
0.71 g NaH2PO4.2H2O
CaSO4.2H2O
0.16 g CaCl2
MgSO4.7H2O
0.21 g MgCl2.6H2O
MgSO4.7H2O
0.17 g K2SO4
Sulfur
Magnesium
Soil culture
Each student or pair of students will require:

Seeds. Radish seeds may be preferred, but others could be tried. For example, rapid growing
brassicas could be used: http://www.philipharris.co.uk/secondary/biology/plants-asorganisms/growing-mix/
Science & Plants for Schools: www.saps.org.uk
Growing Plants in Different Media: p. 1
This document may be photocopied for educational use in any institution taking part in the SAPS programme.
It may not be photocopied for any other purpose.

Soil. A range of soils might be used and compared, including washed sand, vermiculite,
vermiculite/peat mixture and any commercial seed compost low in nutrients.

Nutrient solutions according to the nature of the investigation.

Small container, e.g. film canister, with a hole cut in bottom and a diamond shaped piece of
capillary matting for the wick (see SAPS The effects of different levels of minerals on plant
growth).

Water container with lid, e.g. plastic take-away food container, with a slot cut in the lid for the
wick to pass through and dip into the nutrient solution.
Water culture
Each student or pair of students will require:

Some seedlings, e.g. mung beans, barley or some other plant.

A boiling tube and rack to stand it in.

A piece of aluminium foil.

Nutrient solutions according to the nature of the investigation.
Floating culture
Each student or pair of students will require:

Ten healthy duckweed plants (Lemna) of similar size.

Beaker, with plastic film to cover it

Graph paper

Nutrient solutions according to the nature of the investigation.
Suppliers
Parafilm can be purchased, for example, from Fisher Scientific
(http://www.fisher.co.uk/product/index.php/12378039/Parafilm%20M/Sealing%20film/)
Standard Sachs solutions available from Philip Harris.
Teaching Notes
Students may not be familiar with the types of compounds essential for healthy plant growth.
Explain that they are compounds made from one or more atoms of certain elements.
The three elements whose compounds are need in the largest quantities are: Nitrogen, N;
Phosphorous, P; Potassium, K. The next three needed, but in small quantities are Sulfur, S;
Magnesium, Mg; Calcium, Ca. Plants also need much smaller quantities of compounds of several
other elements.
In some places you may find the expression ‘essential elements’. This can be misleading unless
students know that this is ‘shorthand’ for compounds made from one or more atoms of certain
elements. It’s not the elements that are needed, it is certain ions made from atoms of these
elements. For example,
Nitrate, NO3-; Phosphate, PO43-; Potassium, K+; Sulfate, SO42-; Magnesium, Mg2+; Calcium, Ca2+
The nature of these ions is explored in the sheet Plant Nutrients.
Science & Plants for Schools: www.saps.org.uk
Growing Plants in Different Media: p. 2
This document may be photocopied for educational use in any institution taking part in the SAPS programme.
It may not be photocopied for any other purpose.