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Monday 29th August 2016
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How do plants grow on the roof of houses?


roof fernSometimes you see plants growing out of the grouting on roofs. How do they grow without soil?
Mike, Southwark


** Definitive **
Name: John, Banstead
Qualification: Window cleaner who has to clear lots of gutters out
Answer: The pigeons eat things off the grass, then do their business on their roof, giving nutrients to plants to grow, along with light and water. There are also nutrients in the roof materials

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