Digging into myths about gardening

Did you know:

  • Using a petrol-powered lawnmower for 30 minutes produces as much air pollution as a 50-mile car trip?
  • Chemical fertilisers that are washed by rain into water sources suffocate marine life?

These are facts unearthed by Dr Stuart Farrimond, in his book The Science of Gardening.

Dr Stu is a medical doctor turned science writer whose books explore the science behind everyday life.

He says, ‘For something as beautifully simple as sowing, planting and watering we humans have made gardening terribly complicated.’

Dr Stu asks gardeners to consider whether instead of using petrol-powered mowers, leaf blowers or hedge trimmers they could switch to hand tools or electric alternatives.

He also points out that:

  •  The use of synthetic fertilisers can pollute waterways, whereas soil that is enriched with mulches of organic matter can supply plants with all the nutrients they need.
  • Chemicals used to control weeds, pests and fungal diseases can have unintended consequences as they are by definition poisonous to life. Less harmful ways to limit damage by pests include using methods such as ‘integrated pest management’. 
  • You can plant and manage your plot in ways that maximise its ability to store and retain carbon dioxide.
  • Covering soil with woodchip, compost, straw or rotted manure (mulches) in late autumn protects it from pummelling winter rainfall (each bullet-like drop travels up to 20mph).
  • Soils that are fed annually with organic matter and where digging is minimised will store more carbon than those that are regularly tilled.

Here are a couple of his Myths v Science findings:  

Pruning cuts should be made at an angle

 Flat cuts heal faster; angled cuts leave a larger wound and do not prevent rot by stopping water pooling on the stem.

A layer of crocks or stones at the bottom of containers improves drainage

 The popular advice to prevent fungal root rot in plants in water-logged soil is to place pieces of broken pots (termed ‘crocks) or gravel into the pot before topping up with potting compost.

However, plants in pots with crocks fare no better than those without. The small pores between soil particles hold onto water like a sponge, so that it does not easily flow into the much larger spaces between crocks or gravel. Instead water clings to the lowest layer of soil, where it can accumulate and cause drainage problems. The best advice to avoid water logging is to use good quality potting mix, a pot with drainage holes and to not overwater.

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