Teacher tips 9

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The health risks when growing plants

Growing and planting trees is a wonderful leisure time activity and skills derived at school can lead to a life-time of enjoyment gardening, or being involved in conservation activities.

It is hard to believe but there are some health risks involved. These include pathogenic organisms such as Tetanus and Legionellosis and poisonous plants as well as the risk of insect stings and bites, sunburn, misuse of chemicals and injury caused by garden tools.

The risks of contracting Legionnaires disease from potting mix containing Legionellosis are well-documented, so precautions should be taken to remain safe and healthy when dealing with potting mix.

You and your students should:

  • Minimise the amount of dust around the working area.
  • Water plants with a gentle spray.
  • Read all warnings on bags.
  • Wear gloves when handling potting mix.
  • Wear a dust mask when opening bags or using potting mix to avoid inhaling dust;
  • Open bags of potting mix slowly and away from the face.
  • Dampen potting mixes before use.
  • Make sure the working area (glasshouse, potting shed) is well-ventilated

when working with potting mix during pricking out, potting on and planting.

More information can be found in

When opening bags of potting mix, students are at risk of inhaling dust. One way to reduce the risk is to store potting mix in a large storage bin (similar to the one pictured) which will significantly reduce the likelihood of inhaling Legionellosis when opening bags.

A weatherproof storage bin, located outside on a concrete or paved base, will have better ventilation than in a storage shed. Rather than accessing the potting mix through the lid, ideally the storage box pictured should be modified to allow the mix to be shovelled out from the base, made possible by having one or two removable planks at the bottom.

A couple of hints:

  • The PTA or School Sponsor (or your Board of Trustees) is likely to support funding a storage box since its installation results in improved student health and safety.
  • A functional storage box is easily constructed from 160mm x 20mm timber fence palings with 100mm x 20mm timber supports. The ideal size will be 1m x 1m x 1m. The only other requirement is a couple of hinges.
  • A larger storage box would allow for two compartments, one for storing fresh potting mix and the other for storing used potting mix, as well as leftover potting mix (see below).

Avoid using timber which has been treated, since some treatments can leach into the potting mix and stifle the growth of plants. If using treated timber is unavoidable, you can line the inside with polythene.

TfS schools are provided with potting mix and they should adopt measures to avoid unnecessary wastage. For example:

  • There is always plenty of surplus potting mix which can be swept up from the benches or tarpaulins after pricking out and potting on sessions. This should be saved in your leftover storage box or in some other container.
  • When repotting plants (from root trainers to pots or bags, or from smaller pots to larger) there will be plenty of used and leftover mix to be collected. Again this can be saved in the storage box compartment or a container.

Note that this second-hand potting mix can be reused by mixing 1:4 with fresh potting mix when pricking out in the following year; or even possibly when potting on. You may consider adding pelletised fertiliser as well – consult your TfS Field Officer.

Read more about reusing potting mix here.

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