Miracle-Gro for the mind at the library Rachel Cooke

During the fine weather last week, it felt perverse to duck into the relative gloom of the British Library.

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But inside, mere yards from the traffic-choked Euston Road, I found an oasis in the form of Unearthed: The Power of Gardening, an exhibition that acted like Miracle-Gro on my browning urban mind.

By the time I left, I was sprouting metaphorical new leaves all over the place, my head full of surprising facts, every dandelion in every pavement suddenly more lovely and worthy of attention. (Elizabeth Blackwell’s engraving of the weed in A Curious Herbal of 1739 makes it look as magnificent as a dahlia).

The displays are eccentric, and all the better for it. In one corner, you'll find the first mechanical lawnmower, a monster of a machine from 1832 that was reportedly tested by its inventor, Edwin Budding, at night to avoid his neighbours’ ridicule. In another, you'll see the hobnailed boots worn by that most busy of horticulturists, Gertrude Jekyll. I'm the child of botanists, and growing up I sometimes used to feel I'd die if they said another word about root hairs or stamens. But it was truly thrilling to see a vasculum in which Charles Darwin stored cuttings during trips to South America.