"We have more baristas than barristers, and yet with so much green space in London that we produce two million cucumbers a year from London," he said.
Johnson earlier got the information from the Lea Valley Growers Association (LVGA), which confirmed that 70,000 aubergines are also grown by Lea Valley growers in London.
The association has also hosted a visit from Rosie Boycott, chair of the London Assembly's Food Board. This included a tour from LVGA chairman Gary Taylor of sweet pepper growing at his Valley Grown Nurseries, as well as a tour of Tomworld (Tomatoes) hosted by Joe Colletti and Sam Cannatella.
Boycott learned how growers in the Lea Valley can increase the UK's low self-sufficiency by expanding their growing area to meet London's population growth.