Answer: If you are growing the common annual impatiens, the plants won't set seed (the plants are sterile). If you're growing one of the dozens of other impatiens varieties, the seeds will form in a pod where the flower once was. After the petals fall, look for a green swelling (forming seed pod). When the pod turns a tannish brown, the seeds are ripe and can be collected. Impatiens tend to send their seeds scattering everywhere when the pods are ripe. In fact, they nearly explode and the seeds can be catapulted 20' away from the parent plant! You can collect the seeds by placing a plastic bag over the entire seed pod and touching the pod. A ripe pod will instantly expel the seeds.
As for wintering plants, annual impatiens will die out in the fall regardless of what you do. They will not overwinter and they are not good candidates for indoor growing because the plants last only about 12 weeks.
I don't want to discourage you, but impatiens, as pretty as they are, simply won't behave well indoors. So, enjoy them now while they're at their peak!
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