The color green is almost exclusively used in connection with plants in the Bible (the exceptions include two stomach-turning references to moldy plagues in Leviticus), and the spiritual meaning offered in Swedenborg 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 directly through our senses, since to identify green plants we need to actually see the greenness.
Passages from Swedenborg
Apocalypse Explained (Tansley) n. 507
507. And all green grass was burnt up.- That this signifies that all scientific truth would perish through the desires of the same loves, is evident from the signification of grass, which denotes what is scientific (scientificum), of which more below; and from the signification of green, which denotes that it is true and living from truth, for as green grass serves as food to animals, so scientific truth (scientificum verum) as spiritual nourishment for men. For whatever is produced in fields, gardens, and plains, and serves for the nourishment either of man or beast, has a correspondence with such things as serve for the nourishment of the external (animus) and internal (mens) minds, which nourishment is called spiritual nourishment. Similar things also appear in the spiritual world, from the correspondence of spiritual things with natural things. And because the Word in the letter is natural, and written by correspondences, therefore it is here said, that the third part of the trees, and all green grass, were burnt up, by which is meant, in the spiritual sense, that all perception and cognition of truth and good, and also all scientific truth, perished through those two corporeal, earthly, and merely natural loves.
Arcana Coelestia (Elliott) n. 7691
7691. ‘And they did not allow any green to be left’ means the obliteration of every sensory apprehension of truth. This is clear from the meaning of ‘not allowing to be left’ as obliterating; and from the meaning of ‘green’ as factual knowledge and sensory evidence, here sensory apprehension of truth, since ‘the fruit of the trees’ means recognition of good, 7690, and reference is being made to all the green on trees and on the plants of the field. ‘Green’ means sensory apprehension of truth because truths are meant by ‘plant’, ‘grass’, and ‘leaf of tree’, and from this a sensory apprehension of truth by their greenness. By sensory apprehension is meant the lowest level of perception. A sensory apprehension of truth is also meant by ‘green’ in Isaiah,
The waters of Nimrim will be desolations, for the reason that the grass has withered away, the plant has been consumed, there is nothing green. Isa. 15:6.
And in John,
The fifth angel sounded, and out came locusts; and they were told not to harm the grass of the earth, or any green thing. Rev. 9:4.
Apocalypse Revealed (Rogers) n. 426
426.They were told not to harm the grass of the earth, or anygreen thing, or any tree, but only those men who do not have the seal of God on their foreheads. (9:4) This symbolizes the Lord’s Divinely providing that they be unable to take away any truth or good of faith, or any affection for or perception of these, from any others than people lacking in charity and so having no faith.
Their being told symbolizes the Lord’s Divinely providing, because they were told from heaven. Their not harming the grass of the earth, or any green thing, symbolizes their inability to take away any truth or good of faith; for grass symbolizes the truth of faith that is born first in a person (no. 401), and a green thing symbolizes the life force in faith, which springs from goodness (no. 401).