They divide quite well however spring would have been a better time to do so. You may find the plants sulk over winter and are slow to begin growth in spring.

I worried about the time of year problem too, but I have two Restios that are pushing new culms right now so I was encouraged.

Here's a photo of my new division.

Ans here's a photo of another Thamnochortus insignis showing new culms. It's hard to pick them out in the photo but there are six or seven new ones coming up. The culm on the farthest left is a new shoot and if you count to the right, the sixth is a new culm.

I also rescued a forgotten and neglected Restio, Elegia fistulosa, which was buried in deep shade behind an encroaching plant. I wasn't sure it was going to live but I potted it up maybe two months ago and I started celebrating recently because it has been shooting new culms.

Now I have to worry where I'm going to over winter it because it is a little more tender to cold than others and I don't want to lose it.

My Restio division has a couple of new culms showing! Amazing - I thought for sure it wasn't going to make it.

At last I can be sure my Restio division has succeeded. I decided to cut away all the old culms and it looks ever so much better.