The sky grew dark with the approaching storm clouds.

grew is verb , but dark is adjective I believe.
Would this still be a transitive verb?

In this sentence, grew is a linking verb. The predicate adjective is dark.

Intransitive verb

Intransitive

Ram Milan

In the given sentence, "grew" is not a transitive verb because it does not have a direct object. Transitive verbs require a direct object to receive the action of the verb.

In this case, "grew" is an intransitive verb. It does not require an object to complete its meaning. Instead, it describes the change in the subject, which is "the sky." The word "dark" is an adjective modifying the subject, not an object affected by the verb.

If you want to identify a transitive verb in the sentence, you would need a verb that takes a direct object. For example, if the sentence were: "The storm clouds darkened the sky," the verb "darkened" would be transitive because it takes the direct object "the sky."