Watercress seedlings grow on AeroCloth, a growing material, in a vertical farming bed beneath light emitting diode (or "LED") lamps and using a patented growing algorithm of controlled light, nutrients and temperatures for growing a variety of baby greens at an AeroFarms Inc. indoor vertical farming facility in a former indoor paintball arena in Newark, New Jersey, June 24, 2016. Picture taken June 24, 2016. REUTERS/Mike Segar 

Watercress seedlings grow on AeroCloth growing material in a vertical farming bed beneath light emitting diode (or "LED") lamps and using a patented growing algorithm of controlled light, nutrients and temperatures for growing a variety of baby greens at an AeroFarms Inc. indoor vertical farming facility in a former indoor paintball arena in Newark, New Jersey, June 24, 2016. Picture taken June 24, 2016. REUTERS/Mike Segar 

Employees toss freshly harvested watercress that was grown in vertical farming beds beneath light emitting diode (or "LED") lamps and using a patented growing algorithm of controlled light, nutrients and temperatures for growing a variety of baby greens at an AeroFarms Inc. indoor vertical farming facility in a former indoor paintball arena in Newark, New Jersey, June 24, 2016. Picture taken June 24. REUTERS/Mike Segar 

Watercress seedling grow on AeroCloth growing material in a vertical farming bed beneath light emitting diode (or "LED") lamps and using a patented growing algorithm of controlled light, nutrients and temperatures for growing a variety of baby greens at an AeroFarms Inc. indoor vertical farming facility in a former indoor paintball arena in Newark, New Jersey, June 24, 2016. Picture taken June 24. REUTERS/Mike Segar 

A royal chef checks a Wilted Spring Onion and Water Cress quiche canape, akin to that which is usually served at receptions, at Buckingham Palace in London March 25, 2011. Staff at Buckingham Palace have lifted the lid on preparations for Prince William's wedding next month, giving an insight into what guests can expect and the amount of work they have put in to make the event a success. REUTERS/Nick Ansell/POOL (BRITAIN - Tags: ROYALS ENTERTAINMENT POLITICS)