I planted mexican primrose in my garden in front of the house this spring. They only bloomed for the early part of the summer and then the foliage died back and they began to look twiggy. It's been really dry, so I assumed this was the problem. Now that we've gotten some rain over the last couple of weeks the primrose has sprung up all over the garden. It's blooming, and is very pretty, but I'm afraid it will overrun my garden. Is this an invasive plant?

I'm in Greenville, SC - zone 7. I've been "blessed" with the red clay soil that dominates this area. I completely overhauled the beds in front of the house this spring and tilled in ALOT of compost. Any help or advice is greatly appreciated.

Thanks,
McCay