The first honestly warm week of April finds Union City outdoors — stoops along Summit Avenue occupied, windows up, the whole hill a little louder than it was in March. That is when the grass in the small front plots wakes up rough and shaggy from the cold months, and Rootline Landscaping begins its rounds: first cut, beds redefined, the border along every walk cut back to a single clean line. A sharp edge is most of the trick in a city this dense; it is what separates a cared-for yard from a patch of ground. Through summer the work settles into steady mowing, trimming, mulch and hedge shaping. It is small-scale gardening in a place built vertically, and it holds up the front of the whole block.