Hi Alexandra,

Yes, you can still plant shrubs now.  The most important consideration is to make sure that they do not dry out over the winter.  Because they will not be rooted into the native soil until next summer at the earliest, be sure to check the root ball throughout the fall and winter after planting and water when the top inch or so of soil in that root ball is dry (and temperatures are above freezing).  

Many potted shrubs can also be kept through the winter in their pots.  Again, do not allow them to dry out, and keep the pots shaded and/or covered to buffer them from wide temperature swings.  One common way to accomplish this is to "heel them in" by loosely planting the pots in soil, or most commonly, in a big pile of wood chip mulch.  You could also keep them in an unheated shed or garage, or even on the north side of a building where they won't be in the sun during the day.  Outdoor shrubs should not be kept inside (at comfortable-for-humans temperatures) through the winter; they do need a dormant period in order to remain healthy.

Finally, yes, you can grow shrubs from seed.  When the seeds would be planted and how quickly you'd have a shrub of size depends entirely on the type of shrub you're hoping to grow.  Many natives, in general, appreciate a fall-planting outdoors from seed because they need a cold period in order to induce germination.

I hope this is helpful!

Cordially,

John

You're welcome, and happy planting.

John