London - The time-honoured gardening advice that lining the bottom of plant pots with broken pieces of terracotta improves drainage may be doing more harm than good, claim researchers.
While the tip has been passed down through generations of green-fingered experts, tests suggest the use of crocks – as the leftover bits of old pots are known – is not as beneficial as many believe.
The traditional method is said to let water drain out and stop the soil becoming waterlogged, which can kill a plant’s roots.
However, tests conducted by Which? magazine showed that with regular watering there was no difference between how plants bloomed in pots both with crocks and without – but that in wet summers the crocks can actually prevent excess water draining out and harmed the plants.
Ceri Thomas, editor of Which? Gardening, said: “Despite six-in-ten gardeners telling us they always use crocks in pots, we found this made no difference to how well the plants did in our tests.
“In fact, in wet summers crocks can prevent water draining out of the pot and do more harm than good, so think twice before you follow this commonplace habit.”
Despite the results, Colin Brickell, group plant buyer at Haskins garden centre in Ferndown, Dorset, insists that crocks do help container planting.
He said: “We have always put crocks in our pots and will continue to do so. In January and February they made a big difference because we had so much rain and they helped stop the plants getting waterlogged.” - Daily Mail