Death bloom on the horizon for giant agave

A rare death bloom has begun at Kew Gardens for a three-metre plant, which will come to the end of its life with a spectacular display.

The Agave montana plant, native to the mountainous habitats of north-eastern Mexico, has been growing on average about 10cm (4 in) a day at the west London attraction.

The mountain agave, which was planted around 20 years ago, will open up into a massive cluster of thousands of individual flowers when it blooms.

After that, the parent plant will die. Botanists are looking to cross-pollinate the behemoth, calling it "the UK's most eligible agave".

An asparagus-shaped shoot, called a peduncle, will reach 5m (16ft) in height before sprouting yellow and pink flowers next spring.

Anna Lim, botanical horticulturist at Kew Gardens, said: "This immense inflorescence is an amazing botanical event and it's something we might only get to witness once every couple of decades."

The growth spurt will pause over winter as the agave goes dormant, and the plant will die once it has flowered.

"It really could be a once-in-a-lifetime botanical experience. Once it blooms, I'd encourage everyone to come and see it while they can."

Biological monocarpy

• Monocarpic plants can spend decades without flowering before producing one enormous bloom, but they die after going through a single reproductive cycle
• A monocarp accumulates resources over years and converts them all at once into reproduction
• The flowering event is so costly that no reserves remain to rebuild leaves, repair roots, or hold structural tissue together. Once the carbohydrates, nitrogen, phosphorus and stored water have moved out of the storage organs and into the inflorescence, the parent body cannot recover
• Selection favours this approach when seed production scales steeply with reproductive size: one massive event makes more offspring than many smaller ones spread across a long life

The mountainous succulents do not need watering over summer nor assistance in winter, and so are perfect for drought-like conditions much of England has seen this year.

Thomas Freeth, head of collection management at Kew Gardens, said it was likely the bloom was caused by this summer's extreme heat.

"In many ways it's a tell-tale sign of our rapidly changing climate," he said. "We need to seriously think about how we're going to adapt our landscapes to cope and thrive in these conditions.

"I'm confident we're going to see much more of it and related species planted in our gardens in the coming years."

Listen to the best of BBC Radio London on Sounds and follow BBC London on Facebook, X and Instagram. Send your story ideas to hello.bbclondon@bbc.co.uk