Correct sentence is: After trimming back the deadwood, the rose bush bloomed beautifully in the spring.
Explanation:
Modifiers are used in a sentence which describe other words. They can be a single word or group of words. But sometimes, some modifiers are used incorrectly. These are of mainly three types. Dangling modifiers are errors that are not a part of the sentence. Squinting modifiers makes the meaning of the sentence unclear as one cannot understand the part of the sentence it is describing. A misplaced modifier describes something that is not intended to be described in a sentence. We need fix these type of modifiers by either adding a new word or rearranging the existing construction of words.
In the given sentence, we need to add a dangling modifier "after" to make the meaning of the sentence clear. "After" is describing "trimming back" in the given line.
