Watering containers

Baskets 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.