I just sprinkle the seeds where I want them to grow and press into the soil as these need light to germinate.* You can start them in pots as well.* When the temps reach 70*F they should start to germinate. These plants are considered a half hardy annual.* Basically that means the seed dropped from the year before should germinate.* I don't know your sister's hardiness zone but that would probably be the same.* Massachuttes has hardiness zones of 4 to 7.* They self seed prolifically here in zone 7.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.