My answer uses some sci-fi elements to it, with some handwavy tech. It may not be what you're looking for.
William found a small flier on the table, as he took a seat to enjoy his morning coffee. The flier was made with a lot of care, with a tree-like red frame on the top and the left side holding the company logo while elaborated letters took the rest of the free space against a circuitry-themed background.
There is a new way of life waiting for you!
Stop ignoring the winds of change. The world needs to advance, and the first step begins with you!
Embrace a luxurious, sustainable way of life with the perfect marriage of technology and nature. Help to preserve nature by embracing it on your day-to-day life!
Several advertisements for products that promise to mesh up the power of technology with plant life follow the main text, promising all sorts of benefits over the traditional, tech-savvy lifestyle and the recent vegan/all natural trend. Those claims would seem almost absurd for anyone, wasn't for just a small detail.
Well, not so small.
William looks at the outside, and sees an immense, gigantic building that looks straight out of a book of cyberpunk fantasy in the middle of the nearby park. The mirrored glass intermingles itself with the robust bark of a gigantic black oak. Steel girders and wooden branches sprout from sides at irregular intervals, creating a massive crown over the neighborhood. Its leaves way above the rest of the skyline flow with wind as a massive sea of dark green, the waves dancing as a upside down, mossy-colored wheat field.
That massive cyborg-tree is the current headquarters of one of the weirdest players in the Corporate World. Swimming against the flow, they gave up profits and business opportunities in search for something unique, taking risk after risk and risking bankruptcy over and over again to keep up their morals and their beliefs intact. And, somehow, that suicidal approach to business worked for them - they made it big when their R&D department found out a way to integrate plant life with regular circuitry, enabling the creation of massive, naturally-growing computers which got faster as they got older and bigger. That tree wasn't just a tree - it was a massive dataserver that dished out calculations while it collected sunlight and made photosynthesis. "Those are changing times, indeed", William thought as he sipped his latte and contemplated the ever flowing, almost hypnotic path of the wind over the boughs of the world's biggest computer.
(Sorry for the broken english, it's not my first language!)
Give the tree a public utility that correlates to it's size. The bigger it is, the most the people benefit, and thus there is a direct interest to make it grow.
Alternatively, you can replace the Corporate thing with a religious theme for the same overall effect. I would go with money, however, as it is easier to convince the government to cooperate when there is a direct monetary benefit in game.