I like these cute flowers, but they have invaded my garden. I think I am pulling them out by the roots, turning those areas over, hoping they're gone, to my surprise...more. Without killing my other plants and flowers, how do I get rid of them? Also, can they be transplanted to the neighbor's yard, since she thinks they're cute? I warned her.
There are several evening primrose species. I think you are talking about Oenothera speciosa. You are encountering the result of these pretty plants setting lots of seed. You pull the plants only to have more seeds germinate. If you keep up, you will exhaust the "seed bank", the dormant seeds in the soil that are patiently waiting for the right conditions to germinate. Hoeing will kill the plants. You might consider a pre-emergent like Preen after removing all seedlings. A 4 inch layer of mulch may also work.