The May 21 show sold out last month, and scalpers have been charging as much as 20 times face value for the event, where the Prince of Wales and his Sentebale charity will create a special garden to support African orphans.
"Once people found out who was involved, it was bound to attract extra attention," show director Stephen Bennett told The Daily Telegraph. "We usually sell out in late April or early May, but tickets have gone faster than usual."
The newspaper said the Sentebale garden will be based on flowers native to the African nation of Lesotho and likely have music playing inside. It will be designed by Lesotho native Jinny Blom.
Harry established Sentebale with Prince Seeiso of Lesotho to advocate for children, victims of poverty and those affected by Lesotho's HIV/AIDS epidemic.