The Royal Horticultural Society said the Puya chilensis, a native of Chile with a 10-foot tall flow spike, is likely to bloom in the next few days and the bloom is expected to last about a week, the BBC reported Friday.
In its native Andes Mountains it uses its sharp spines to snare and trap sheep and other animals, which slowly starve to death at the base of the plant and then decay, providing the plant with fertilizer.
The British specimen in a Surrey greenhouse isn't on a sheep diet.
"We keep it well fed with liquid fertilizer as feeding it on its natural diet might prove a bit problematic," horticulturalist Cara Smith said. "It's growing in the arid section of our glasshouse with its deadly spines well out of reach of both children and sheep alike."
Very few specimens of the plant have ever been known to have flowered in Britain.
"I'm really pleased that we've finally coaxed our Puya chilensis into flower," Smith said.