Sentence Correction

One of the rules I learned was that "a phrase must be right beside what it modifies." My question is that if the modified noun has to be physically right next to the phrase, or it can be somewhere in the modified sentence as long as there isn't any confusion.

I encountered two practice questions with clauses being modified by phrases that are not close to each other.

1)Analysts blamed May's sluggish retail sales on unexciting merchandise as well as the weather, which was colder and wetter than was usual in some regions, slowing sales of barbecue grills and lawn furniture.

In this sentence, the underlined phrase modifies weather that is pretty far away from it. My guess is that "which was" is omitted before "slowing".

2)The root systems of most flowering perennials either become too crowded, resulting in loss of vigor, or spread.

In this sentence, the underlined phrase modifies "the root systems of most flowering perennials" that isn't right next to the underlined phrase.

Any guidance will be greatly appreciated!


:roll:

Can any expert help us with this? Please!