Earlier this week, Left Foot Forward made a suggestion that the Green Party should consider affiliating with Labour: https://leftfootforward.org/2017/07/is-it-time-for-the-green-party-to-affiliate-to-labour/
This is something that, for the sake of our environment, humanity's future, and genuinely progressive causes, must never happen.
Labour have no real respect for our environment or for co-operative politics. They were happy to take advantage of the failed 'Progressive Alliance' for their own gain, even in seats where victory was already assured, but were unwilling to ally when they could not win or where a different party had a better chance of winning the seat from the Conservatives (especially in the case of the Isle of Wight). They were also unwilling to put key environmentalist policies, or even electoral reform, on their manifesto or in their broadcasts. They are also still focused on a pro-growth policy, which cannot be sustained in the long-term as the planet's resources are not infinite (and many are not renewable), and that technological development can only go so far. Sustainability is an important watchword we must take note of, as is stability.
The Greens are not a socialist/social-democratic party and were not designed as one. Green politics and values have always been distinct from Labour's, due to their focus on environmental wisdom, peace, grassroots democracy, and indicators other than economic productivity. Happiness and health are also important to humanity, and other political parties simply do not accept these as primary indicators of human performance. The Green Party was founded to build a new ecologically sustainable and fair society, not modify one that is a fundamentally part of a failed system (which is Labour's aim).
My three words in response to the question 'Is it time for the Green Party to affiliate to Labour? within the article are: no, nay, never.