pygmy chain sword isn't growing
Hi I have soil under 3"/4'' of 2-3mm gravel, I also put root tabs under these cheeky lil monkeys and they still dont spread out. I got a mix bag of 50 stem plants from a local company for £9.98. I got 3 lots of these swords in with it. I was really excited to see it spread out like a nice lawn, but it hasn't, any ideas/experiences?.
P.s its staying alive really well, nice and green, but no growth.
I use a small amount of fertiliser and thats it.