Green with envy = very envious or jealous.

• Renz is heading off to Dubai for a week, and I am green with envy.
• Singapore’s economy turned the world  green with envy.

Get green fingers or have green thumb = be good at gardening or planting seedlings.

• My mother has got green fingers.  Everything she plants in the garden grows well.
• My husband has green thumb.
• His sister can keep any plant alive, even the ones that he’s nearly killed;  she seriously has green fingers.

Green light = permission.

• The council has given the green light to the new shopping centre.
• We’re just waiting to get green light from our managers before we release the latest software update.
• As soon as we get the green light , we’ll start advertising for new staff.