S repens they look good. May be try trimming a few to see if that gets them to spread. Other than they look healthy. Though compared to mine. Yours are a bit leggy lot of space in between the nodes/leaves mine are a lot more compact and bushy. Maybe more light u need
StevenJohn21 is that why plants send of those extra roots? Seems impossible to me. I have fresh mgops with a fluorite cap and does flourish and iron with potash. And some of my plants do that too is very weird.