For those without green thumbs, it's often a mystery why some plants thrive and others shrivel away.

For Des and Allie Brennan of Protective Solutions Ltd in England, it's become a very, very big mystery.

Bringing in a small potted pothos cutting in 2009, they merely wanted to brighten up the workspace. Now, more than 14 years later, the ivy has grown to almost 600 feet long—sprouting new shoots that require pinning up across the office walls and ceiling nearly every day.

It hangs from computer monitors—and even has its own sponsorship deal.

"It started off as a bit of a laugh but we wouldn't be without it now. We'd have to get another one if it ever went," Allie explains.

The ivy grows at an impressive rate of six inches per month and covers almost the entire office of the Brennans Gloucester-based packaging company Des founded in 2006.

"We try to keep it off the desks so it doesn't get in the way but it hangs down and is joined onto the monitors," said Allie. "It makes a massive difference to the office. We can't envision the place without it—it would be dire."

The open-concept office plan only measures 50 by 25 square feet, meaning that the monstrous ivy has to crisscross the ceiling back over itself a few times.

"It's a big talking point when customers come in as well. People ask if it's real but I'm not sure where we'd get a fake one this size."

Allie added at the plant is very low-maintenance, requiring some feed and some water only once a week.

The plant has even received a sponsorship deal from a gardening company called Gardening Naturally, which provides seaweed extract food to the office.

Although Allie suspects if the plant continues to grow they'll have to "bring machetes to the office" to hack through the growth—she says staff love the greenery.

"It changes daily. Sometimes it's a bit creepy coming in and seeing it changing again," said Allie. "The most time it takes up is taking the time to pin up the new shoots. Over lockdown the office was manned the whole time, according to guidelines. It was still looked after and the office air was probably purified for it."

"Staff love it. If it was gone we'd all notice it and we'd just have to get another."

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