Seams showing in your artificial grass: a visible line, or an open gap?

A seam is two pieces of turf joined edge to edge, typically with seam tape and adhesive underneath the backing, then groomed so the fibers blend and hide the joint. A visible but closed seam, a faint line you can see from certain angles or in certain light but cannot get a finger under, is almost always a grain-direction mismatch, where the two pieces were not oriented identically, or simply grooming and infill that have worn differently on either side of the joint over time. An open seam is structural: the tape or adhesive bond has failed, the two edges have pulled apart, and you can see backing material or feel a gap when you press on it.

Run a hand along the line. If it is flush and firm with no gap and no movement, it is cosmetic, whatever it looks like. If you can work a finger in, feel the edges move independently, or see backing material through the gap, it is open and structural. Look at it from a couple of angles and times of day too, since grain-direction lines can look more obvious in low, raking light than they really are underfoot.

A cosmetic, grain-direction seam is improved with grooming and, where infill has worn unevenly, topping it up along the joint; it rarely needs to be redone since there is no structural problem. An open seam is cut back, cleaned, retaped and reglued along the full run with fresh seam tape and adhesive, then groomed to blend. That is turf repair, with re-seaming priced from $250 depending on length and access. An open seam left alone widens with every step and lets soil and weed seed in from below, which is why it is worth doing sooner rather than later.

Avoid dragging heavy furniture or equipment across a seam repeatedly, since that is one of the more common ways an otherwise sound seam starts to work loose. Check seams the same way you check edges, on a perimeter walk after a big storm or once or twice a year, so an open seam gets caught small rather than after it has run the length of the yard.