Reprising his judge role, the 73-year-old was tasked with casting his expert eye over the This Morning pair’s efforts as they shaped their greenery into a pyramid dome.
As gardener Charlie Green taught the duo how to shape potted bushes, Rylan and Alison set about having a race to see who could make their creation the fastest.
After the presenting team battled with their shrubs, the clock came to an end and it was down to an astounded Len to judge their talents.
Starting with Celebrity Big Brother’s Rylan, Len joked: “To be honest Rylan, I thought you would be good at this because of your beard.
“It’s a bit mankey, I’ve got to be honest,” he admitted, before giving the 28-year-old one of his famous sevens.
Alison, 42, fared better, with Len telling her: “You got stuck in, you were working your hips.”
Rylan claimed the competition was a fix when the former Strictly Come Dancing judge gave his co-host “a ten from Len”.
Elsewhere on the ITV show, viewers were disgusted as a woman recalled her “filthy” lifestyle so early in the day.
This Morning airs weekdays on ITV from 10.30am.