We’re sure you will all agree that for as long as you can remember gardeners have been advised to put broken pieces of pottery at the bottom of plant pots to aid drainage. But recent research has put a question mark over the theory.
The case for
Broken pottery at the bottom of the planted pot is said to allow water to run off more quickly than soil alone would. This prevents the soil from clogging up the holes at the bottom of the pot – well so we all thought!
The case against
The consumer magazine Which? carried out a study to test this tradition. 40 pots were planted with 5 ‘million bells trailing yellow’ each. This particular plant was chosen as it is renowned for root rot in saturated soils. The variants included plastic pots and terracotta pots. Half were planted with crocks and the other half without. The plants were then monitored and rated on ‘vigour and flowering impact’. The results suggest that crocks had no impact on how well the plants did.
Can this be true gardeners
Guy Barter, Chief Horticultural Adviser at the RHS agreed with the findings and said that crocks are actually likely to worsen drainage by creating a block. Although this could be a good thing in very hot weather.
He suggested that having a layer of sand at the bottom of the pot is a much more effective alternative as it allows the water to drain into it but also be sucked up by the roots if needed.