To discuss an upward trend in PS here are my rules of thumb.
1) the vast majority of students: NO! I get people who got a B, B- or, god forgive C and want to plead their case. Just shut up and move on
2) those who had a rough freshman year: mention solely in passing, in a phrase, in less than a sentence Something about improving maturity and study discipline. Anything more, NO!
3) a rough middle semester: as above or if with brief reasonable cause again less than a sentence
4) nontrad with old mediocre work. Maybe a sentence or two if that much
5) really poor work followed by upward trend and/or postbacc-smp. Depending on story no more than 2-3 sentences
6) highly unusual circumstances such domestic abuse, sexual attack, death of parent, serious illness etc may need more
All of these would always, always, always, lead the positive growth in the same sentence or following sentence
Again, most applicants shouldnt be mentioning anything. This OP would seem to have nothing to say on this issue