GARDENERS must be patient as they wait for their carefully-nurtured plants to flower. But few will have faced quite the wait endured by staff at the Royal Botanic Gardens, at Kew, where a plant has flowered for the first time after almost 40 years.

Just before flowering, the Agave franzosinii more than quadrupled in height – growing a rate of almost 3ft a week until it was as tall as a house.

The growth spurt was such that the plant outgrew its west London conservatory, forcing staff to remove parts of the roof to allow its progress to continue. When it did finally bloom, most of the 3in yellow, trumpet-shaped flowers were outside the building.  However, the glorious display did not last long. Agaves die shortly after flowering and four months after the start of the growth spurt, the plant had to be felled by Kew’s tree management team.

The species is found in the wild in Mexico where it can even take longer to flower and reach greater heights. Kew’s specimen could actually be older than 40. The gardens’ records show it joined its collection in 1973 but do not indicate whether it was a seed or a plant at this point. It was initially grown in a pot, but was planted in the Princess of Wales Conservatory in 1989. Before its final growth spurt, it stood at around 6ft in height, with large leaves spreading over a 6ft diameter. –TG

Then, last June, it started to produce a stalk, or “spike”, which grew for around two months, reaching a height of around 29ft. It then flowered at the top, for a further two months.

Lara Jewitt, keeper of the Princess of Wales Conservatory, said: “I knew it was about to start growing because just before it did, it wasn’t looking very good. It had lost all its vigour and looked a bit wilted. This is because it is putting all its energy into starting this monstrous spike.

“Once it started, you could see it growing daily. This is the biggest one I have ever seen flowering, and also the longest period taken to flower.”

The plant is of the same family as the Agave tequilana, which is used to make the spirit tequila. Collectively they are known as “century plants”, as it was previously thought they only flowered every hundred years.

Where they grow in arid parts of Mexico, they are an oasis for wildlife, as they are full of pollen and nectar, attracting birds, bees and bats.

By chance, the flowering took place while Sir David Attenborough was filming at Kew Gardens for a new series, Kingdom of Plants 3D, which is due to be broadcast on Sky in May. Its progress was filmed for the show.

Before it died, staff at Kew took some seeds from it, which have already been sown and reached around 2ft in height. They are expected to flower some time around the middle of the century.