yeah- some of the reuellias are known to be invasive. i have the purple/blue with dark foliage and it spreads even in the worst spot in my yard- right by the mailbox/rd.

Does it spread by seed or by roots? I have heard the roots are impossible to erradicate, but those are mainly people in Florida and warmer climates. If it's just seeds, I can handle that, but I don't want to be digging out roots forever!

I think it may depend on the location. I don't water mine here in Durham (where we get very little rain during the summer) and it barely grows, let alone bloom. But it does spread by roots. You could try planting it in a bottomless buried container. It IS a beautiful plant.

roots, for sure. and i have mine out by the mailbox in gravelly clay mess in full sun that NEVER gets watered except by rain and it still spreads. Of course, it also blooms from june til frost, so i don't mind too much. Where it is it can't really spread but one direction, and only a few inches there, so it's a decent spot for it. A big pot or barrel would be a good way to contain it. It's not at the same level of invasiveness as gooseneck loosetrife, bamboo or the low pink primrose, so it's ok if you have a place you can control it. I haven't noticed seedlings around, but it might reseed.

I'm going to plant it in some pretty tough growing conditions. Right next to the crocosmia I'm getting at the swap. LOL

Costa Farms sells a Florida Friendly variety at Home Depot. It is supposed to be sterile. I planted mine at my house in Florida over a year ago, and they have not spread - they really are beautiful!!!
Shortly after I planted them, sorry I thought I had a current picture, too!!
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Christy, it looks beautiful with your grasses!
I bought 8 plants this June from the little garden place down the street. He was selling them for a buck a piece.
SO I planted 4 together in 2 different places out towards the street on my front lawn.
They are absolutely beautiful!
My soil is so bad, poor, sandy, with bahia grass growing all in it, I had to cut the bahia grass back from the petunias!
I hope they live and bloom again next year.
I don't even care if they spread, but with my poor soil, I'm just happy they survived this dry summer.

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Pretty!
I've only ever had the mound type of ruellia with a rose colored bloom and it didn't spread by roots but by seeds and nothing impossible to dig and transplant.

Mine are still thriving!! And look great from what I hear, we rented out that house. Still no spreading!!! Thanks Butterfly!!!