The Royal Parks will also supply some pollinator-friendly plants from their wildflower meadows, which will be incorporated into the floral designs.
He announced his engagement to 36-year-old Markle in November.
Britain's Prince Harry and his American fiancee Meghan Markle have chosen a London florist beloved of the fashion industry to arrange the flower decorations for their wedding in late spring, Kensington Palace said on Sunday.
A new biograpjhy about Meghan Markle's life before she met Prince Harry has portrayed her in a very different light.
A month before their 2011 wedding in Jamaica, Markle learned that the series was picked up for a second season, this time shooting in Canada-an even greater commute for the couple.
Some of the other guests who will be interviewed for the special include Markle's half-sister Samantha Markle, Princess Diana's former butler Paul Burrell, Piers Morgan, Dickie Arbiter and more.
Royal biographer Andrew Morton has described her as "calculating" in his novel Meghan: A Hollywood Princess.
They added that Markle "wants to be Princess Diana 2.0".
Mr Markle divorced Doria, who went on to become a social worker, when their daughter was six.
With Engelson based in Los Angeles, the couple thought "the sacrifice was going to be worth it", Morton writes.
He continues, "She also packed on a "freshman 15" [pounds] - weight gained from drinking, munching starchy dorm food and making late-night trips to the 24-hour Burger King".
She ended their marriage "totally out of the blue", sending their rings in the mail after walking out with a blender from their West Hollywood home and moving to Toronto.
According to British wedding site Bridebook, Markle's upcoming wedding is reportedly estimated to cost around $44.9 million, or £32 million, about $20 million more than Prince William and Kate's reported $28 million nuptials.
On that occasion, the sister of the bride Pippa Middleton, 34, took centre stage when she was Kate's bridesmaid with a dress highlighting her posterior.
One of Markle's childhood friends told Morton that the actress was "always fascinated by the royal family". She cancelled "lunches on short notice" or expected friends "to rework their own schedules to accommodate the busy life of the rising star".