Growing media

There's no legal requirement for packaged growing media products to display a statement of quantity. If they do, the amount shown must be the net quantity.

New Zealand Standard for composts, soil conditioners and mulches

The legal requirements of the Weights and Measures Act take precedence over any requirements in the voluntary New Zealand Standard NZS 4454:2005 Composts, soil conditioners and mulches.

NZS 4454:2005 Composts, soil conditioners and mulches(external link)

Following testing and evaluation by Trading Standards, we consider that this Standard should be updated. In the meanwhile, if you're using the Standard, we recommend you make the following adjustments to ensure you comply with the Act.

Section in NZS 4454:2005Adjustment to make
Section Replace the method for determining the volume of packed material with the Test procedure below.
Section The actual volume of packaged product must not be less than the volume stated on the primary package.
Section 3.2.2(b) See the page General labelling requirements.

Determining compliance

Trading Standards Officers will use the test procedure below to determine whether a batch of growing media products meets the specific requirements in the Weights and Measures Act and Regulations.

For more information see Trading Standards inspections.

Test procedure

This test procedure is for manufacturers and packers to determine the volume of bags of growing media products up to and including 50 litres.

Required equipment

You'll need the following equipment for the testing procedure:

  • A single calibrated container, equal to or greater than the stated quantity on the package to be tested. The container should be marked at graduations of 0.5L and 1L either side of the stated quantity to allow an error to be detected. To calculate the graduation marks, either:
    • submit the container to Trading Standards for calibration and reporting, for a small charge, or
    • use a measure of known volume, such as a 10L measuring jug, and mark the container at the appropriate graduations.
  • A second container with a greater volume than the package to be tested.
  • Scissors or a knife.
  • Gloves.
  • Mask.
  • Quantity Sampling Records (see example in Step 8).

Selecting test packages

Test package(s) should be selected at random from a completed batch of packages, once all packing and stacking has been completed. This includes packages from the centre of the pallet.

Tip Icon Blue2 Note

The Trading Standards test procedure is to obtain packages from finished pallets — but you don't have to do this. You should develop and maintain a sampling procedure that gives you confidence that the actual quantity contained in the package equals the stated quantity. If you choose to sample from the production line, you should account for any deficiency in contents caused during the packing process.


Step 1

Place the package on a level surface.

package on table

Step 2

Roll the package back and forth lengthwise for 6 full rotations to allow the product to be sufficiently aerated (one full rotation shown).

person rolling package back and forth

Step 3

Carefully and slowly lift the bag into a vertical position.

person lifting package to vertical position

Step 4

Open the upper end of the package along the seam so there are no remaining edges that could restrict the natural flow required in Step 5.

person opening package along the seam

Step 5

5.1 Lift the open bag and rest it on the edge of the calibrated container and allow all product to gently flow into the calibrated container.

person pouring contents of package into a calibrated container

5.2 To enhance product aeration, lift the calibrated container and rest it on the edge of the second container. Allow product to gently flow into second container.

person pouring contents of calibrated container into another container

Step 6

6.1 Return product to the calibrated container using the method in 5.2 above.

person pouring contents from container back into calibrated container

6.2 Minimise bumping or knocking the container, as this will cause the material to compress.

Level off the surface material.

person with gloves leveling surface of contents in calibrated container

Step 7

Calculate the actual volume of the product from the graduated strip on the container.

contents with graduated strip measurements on the container

Step 8

Document the actual volume as shown in the example below, and keep these documents for 6 months.

Date/timeProduct nameStated quantity on packagingMeasured quantitySignature
20/6/2013 13:30 X Compost 40 L 41 L x
21/6/2013 15:00 X Potting Mix 40 L 40 L x


Offences under the Weights and Measures Act and Regulations include:

  • Supplying goods where the actual quantity is less than the stated quantity - Section 16A.
  • Obstructing a Trading Standards officer from their duties - Section 32(c).
  • Quantity statement not in the correct form - Regulation 80.

Weights and MeasuresAct 1987 — Section 16A(external link)

Weights and Measures Act 1987 — Section 32(external link)

Weights and Measures Regulations — Regulation 80(external link)

See What to do about short quantity packages for more information.

If your goods are found by a Trading Standards Officer to be short of their stated net quantity, you may be subject to one of the following enforcement actions:

  • Letter of warning.
  • Infringement Offence (fee) of $500.
  • Fine of up to $10,000 on prosecution.

Calibration services

We operate 3 International Accreditation New Zealand (IANZ) accredited laboratories that provide testing services for volume measures.

See Contact us for more information.