The INSIDER Summary:

• Kate Middleton wore a green floral dress at the Chelsea Flower Show on May 22.
• The $1,950 midi dress from the French designer Rochas has already sold out online.

Kate Middleton demonstrated flawless style and etiquette in a blush Alexander McQueen midi dress at her sister Pippa's wedding over the weekend.

A couple of days later, on May 22, Kate made another stylish appearance in a second midi dress at the Chelsea Flower Show in London.

The Duchess of Cambridge wore a floral, short-sleeved green dress by the French designer Rochas, for the occasion, coordinating perfectly with the theme of the annual spring event.

Within hours of Kate wearing the $1,950 dress, it sold out online, proving that the duchess has some serious pull in the retail industry.

Though Kate's outfit is no longer available to buy, as Refinery29 points out, another designer will probably make a cheaper knock-off version of the pleated, below-the-knee dress.

Kate isn't the only celebrity to wear a Rochas outfit. "The Handmaid's Tale" star Elisabeth Moss recently chose an ensemble from the designer to wear on Stephen Colbert.

And Katherine Heigl wore a Rochas dress with a similar floral print for her appearance on Jimmy Kimmel.

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