The UK's biggest plant library is under threat from biscuit beetle as the Royal Horticultural Society has had to freeze all its plants to kill off the pest.

The RHS is due to launch its new, digitised, herbarium which will help gardeners plan their blooms with helpful depictions of species and plant guides.

Their herbarium has had to be designed to be biscuit beetle-proof, and plants inside are stored at a low temperature that is known to prohibit the beetle from completing its life cycle. As they move into the new storage area, plant scientists will be ‘decontaminating’ the specimens to ensure that the new area is not contaminated, by placing them in a humidity controlled heat chamber.

Biscuit beetles have been ravaging plants since the Ancient Egyptian times, and love to burrow through dried plant matter, damaging it — which makes a herbarium full of dried plants a perfect place for the beetles to breed.

The herbarium contains specimins dating from 1731, and while keen gardeners had to travel to RHS Garden Wisley to view the 86,000 plants, now they will be able to look online.

Interesting specimens include a potato collected by Charles Darwin and geranium that sprung from the spot where the Prince Imperial, son of Napoleon III, died. They will all be available to search on the RHS website from autumn 2020.