They reseed and spread.

And they do both with little to no water.

For flat plants like this you have to be providing just the right soil or there may be perpetual problems with weeds coming through it. Basically it is a rock garden plant, with attendant levels of maintenance to be likely.

I was once charged with keeping a large mat of woolly thyme weeded with a dinner fork. The soil was too moist for the thyme to out-compete tiny rushes and other moisture-loving weeds from constantly coming through it. The thyme was able to establish and cover the planting area but not able to suppress the other plants, which liked the site too well for that.

It was an impossible task, I was supposed to keep up an entire garden as well as spend many hours popping out the rushes etc. - each time pushing the thyme back down that came up with the weed after picking the loosened weed out.

You have to be possessed of a burning passion for rock gardening to be willing to engage in the kind of detail work it requires.

I have both Blue Haze and the purple one and Blue Haze is more vigorous and also has the burrs which I haven't seen on the purple one. I like them but they do require weeding like bboy says. They do look nice and fill in.

Thanks everyone. The aceana is planned for a very small area, and is part of a texture of groundcovers, so I think I'll try it. I'm permanently in a weeding position anyway.

Maybe change your screen name to lisabendingonbainbridge.

Has anyone tried a pseudopanax "sabre"? What conditions does it like here? Thanks all.

I do grow the purple acaena and it does really well in my garden but it's true that weeds can grow through it easily. It's on a slope so it doesn't get much water. It's in a very rich soil too. I had it in my previous house where it got lots of sun. It produced tons of burs which my dog kept bringing home in her fur ;)
My current house has less light and I haven't seen it flower yet.

bboy, I like the screen name change--very funny, and sadly too appropriate! Thanks

Knee pads can help.