Green
The color green is almost exclusively used in connection with plants in the Bible, and the meaning is closely connected to the meaning of plants as well. Plants, in general, represent facts, knowledge that we can gather from the world. Green plants are ones that are alive and growing. Since life represents love and goodness, it makes sense that green plants are facts that have the potential for good use. It also indicates that they are the kinds of things we learn through directly through our senses, since to identify green plants we need to actually see the greenness.
(References: Apocalypse Explained 507; Apocalypse Revealed 426; Arcana Coelestia 7691)
Matthew 24:30
30
And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.