Prince William, Duchess Kate and Prince Harry visit Princess Diana's memorial garden

Prince William, Duchess Kate and Prince Harry paid tribute to Princess Diana with a stroll through her Kensington Palace memorial garden on the eve of her 20th death anniversary.

William, Kate and Harry were given a tour by head gardener Sean Harkin, along with gardener Graham Dillamore who knew Diana from her frequent visits there. The royals were educated on designing and maintaining the garden, as well as Princess Diana's favorite flowers.

The palace's Sunken Garden was transformed into a White Garden in honor of Princess Di this year.

A team of six gardeners and a number of volunteers spent 18 weeks planting white roses, white Diana tulips, white hyacinth, forget-me-nots and other favorites of Diana's back in April. In July, flowers with a different bloom -- including classic English white roses and Cosmos daisies -- were planted. According to Kensington Palace, the garden will continue into September with white roses, lilies, gladioli and cosmos.

They then met some representatives from the numerous charities Diana worked with, including the National AIDS Trust, The Leprosy Mission and Royal Marsden Hospital. Of course, the trio had a conversation with the group about Diana's philanthropic legacy, which continues to impact people even today.

William, Kate and Harry looked like they were in good spirits, despite the rainy outing. The trio totted umbrellas as they walk on the garden's grounds. Duchess Kate donned an appropriate outfit for the garden event, wearing an eye-catching floral frock from Prada that hit just below her knees.

Tomorrow, August 31, marks the 20th death anniversary of Princess Diana following a tragic car crash in Paris. For more on her death anniversary, watch the video above.