Watering containers

water from hoseBaskets and containers are notoriously thirsty, but careful watering will save water and allow plants to flourish.

Scientist Tijana Blanusa and a team at the School of Biological Sciences, University of Reading, with funding from the RHS, set up experiments using petunias and busy lizzies to monitor amounts of water take-up by the plants.

There were three major findings:

  • First, there is no need for hanging baskets and containers to drip after watering: bedding plants performed well when watered little, but daily. It took 160ml (about 6fl oz or a teacup) of water each day to saturate the compost supporting each petunia, but only 80ml was needed to grow a good plant. In neither case did compost drip after watering.
  • The second surprise result is that irrigation applied 5cm (2in) below the soil surface, through porous hose systems, increased plant quality even though the upper soil was dust-dry.
  • The third outcome confirms what gardeners have long suspected: overwatering leads to poor-quality plants.


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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.