Prince William, Prince Harry to honor Princess Diana at garden ahead of the 20th anniversary of her death

Diana was just 36 when she passed away nearly 20 years ago.

A team of six gardeners and a number of volunteers spent 18 weeks planting the floral tribute of white roses, white Diana tulips, white hyacinth, forget-me-nots and other favorites of Diana. The "White Garden," as it’s known, opened in April.

William and Harry were just 15 and 12, respectively, when their mother died at age 36 in a car crash in Paris.

For the 20th anniversary of the princess of Wales' death, William and Harry decided it was the appropriate time to remind people of their mother's legacy, and participated in two documentaries about her life.

Both princes have vowed to keep their mother's memory alive and have thrown themselves into various charitable projects that reflect her interests and passions.

William and Kate formed their charity, Heads Together, with Harry to help break down the stigma around mental illness.

The brothers have participated in a series of other projects to commemorate their mother's life. In addition to forming the garden dedicated to Diana, Kensington Palace is holding a special exhibition chronicling her life; the centerpiece of the public exhibit is the desk where Diana organized much of her charitable work. William and Harry have also commissioned a statue of their mother which will be erected on the grounds of Kensington Palace.

"I think constantly talking about Granny Diana. So we've got more photos up 'round the house now of her and we talk about her a bit and stuff," William said recently in an interview for an ITV documentary commemorating his mother's life. "And it's hard because obviously Catherine didn't know her, so she cannot really provide that -- that level of detail. So I do regularly, putting George or Charlotte to bed, talk about her and just try and remind them that there are two grandmothers, there were two grandmothers in in their lives, and so it's important that they know who she was and that she existed."