If you're planning to go see the thousands of plants on parade during the Chelsea RHS Flower Show at Royal Hospital from 20th–24th May (open to non-RHS members 22–24 May), dining afterwards won't be a problem. A number of neighbourhood restaurants will offer special menus in keeping with the nature of the event (and yes, you can even eat some flowers if you want to):
Bluebird will serve garden-themed cocktails in the bar and a garden-inspired menu in the restaurant with ingredients such as peas, asparagus, beetroot, dandelion, rhubarb and blackcurrants; see the menu (19–24 May, lunch and dinner; £15.50 for two courses; £18.50 for three courses and a glass of champagne; 020-7559 1000).
Le Cercle’s tasting menu is based on edible flowers and includes dishes such as sea bass tartar with vanilla oil, pomegranate and nasturtium (20–25 May, lunch and dinner; £39 for four courses; £42 for five courses and cheeses; 020-7901 9999).
For the duration of the garden show, Trinity has a special for diners who mention the event when booking a table – a special three-course menu and a complimentary elderflower Bellini; further menu details TBD (£20 per person; 020-7622 1199).
And while The Greenhouse is in Mayfair, not exactly in the Flower Show neighbourhood, they'll have a special flower/herb/nature-inspired menu on offer at lunch from 20th–24th May (£25 for two courses; £29 for three courses; 020-7499 3331).